The Pulsar Python client library is based on the existing C++ client library. All the same features are exposed through the Python interface.

Currently, the only supported Python versions are 2.7, 3.4, 3.5, 3.6 and 3.7.

Install from PyPI

Download Python wheel binary files for MacOS and Linux directly from the PyPI archive.

#!shell
$ sudo pip install pulsar-client

Install from sources

Follow the instructions to compile the Pulsar C++ client library. This method will also build the Python binding for the library.

To install the Python bindings:

#!shell
$ cd pulsar-client-cpp/python
$ sudo python setup.py install

Examples

Producer example

#!python
import pulsar

client = pulsar.Client('pulsar://localhost:6650')

producer = client.create_producer('my-topic')

for i in range(10):
    producer.send(('Hello-%d' % i).encode('utf-8'))

client.close()

Consumer Example

#!python
import pulsar

client = pulsar.Client('pulsar://localhost:6650')
consumer = client.subscribe('my-topic', 'my-subscription')

while True:
    msg = consumer.receive()
    print("Received message '%s' id='%s'", msg.data().decode('utf-8'), msg.message_id())
    consumer.acknowledge(msg)

client.close()

Async producer example

#!python
import pulsar

client = pulsar.Client('pulsar://localhost:6650')

producer = client.create_producer(
                'my-topic',
                block_if_queue_full=True,
                batching_enabled=True,
                batching_max_publish_delay_ms=10
            )

def send_callback(res, msg):
    print('Message published res=%s', res)

while True:
    producer.send_async(('Hello-%d' % i).encode('utf-8'), send_callback)

client.close()

#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
#

"""
The Pulsar Python client library is based on the existing C++ client library.
All the same features are exposed through the Python interface.

Currently, the only supported Python versions are 2.7, 3.4, 3.5, 3.6 and 3.7.

## Install from PyPI

Download Python wheel binary files for MacOS and Linux
directly from the PyPI archive.

    #!shell
    $ sudo pip install pulsar-client

## Install from sources

Follow the instructions to compile the Pulsar C++ client library. This method
will also build the Python binding for the library.

To install the Python bindings:

    #!shell
    $ cd pulsar-client-cpp/python
    $ sudo python setup.py install

## Examples

### [Producer](#pulsar.Producer) example

    #!python
    import pulsar

    client = pulsar.Client('pulsar://localhost:6650')

    producer = client.create_producer('my-topic')

    for i in range(10):
        producer.send(('Hello-%d' % i).encode('utf-8'))

    client.close()

#### [Consumer](#pulsar.Consumer) Example

    #!python
    import pulsar

    client = pulsar.Client('pulsar://localhost:6650')
    consumer = client.subscribe('my-topic', 'my-subscription')

    while True:
        msg = consumer.receive()
        print("Received message '%s' id='%s'", msg.data().decode('utf-8'), msg.message_id())
        consumer.acknowledge(msg)

    client.close()

### [Async producer](#pulsar.Producer.send_async) example

    #!python
    import pulsar

    client = pulsar.Client('pulsar://localhost:6650')

    producer = client.create_producer(
                    'my-topic',
                    block_if_queue_full=True,
                    batching_enabled=True,
                    batching_max_publish_delay_ms=10
                )

    def send_callback(res, msg):
        print('Message published res=%s', res)

    while True:
        producer.send_async(('Hello-%d' % i).encode('utf-8'), send_callback)

    client.close()
"""

import _pulsar

from _pulsar import Result, CompressionType, ConsumerType, InitialPosition, PartitionsRoutingMode  # noqa: F401

from pulsar.functions.function import Function
from pulsar.functions.context import Context
from pulsar.functions.serde import SerDe, IdentitySerDe, PickleSerDe
from pulsar import schema
_schema = schema

import re
_retype = type(re.compile('x'))


class MessageId:
    """
    Represents a message id
    """

    'Represents the earliest message stored in a topic'
    earliest = _pulsar.MessageId.earliest

    'Represents the latest message published on a topic'
    latest = _pulsar.MessageId.latest

    def serialize(self):
        """
        Returns a bytes representation of the message id.
        This bytes sequence can be stored and later deserialized.
        """
        return self._msg_id.serialize()

    @staticmethod
    def deserialize(message_id_bytes):
        """
        Deserialize a message id object from a previously
        serialized bytes sequence.
        """
        return _pulsar.MessageId.deserialize(message_id_bytes)


class Message:
    """
    Message objects are returned by a consumer, either by calling `receive` or
    through a listener.
    """

    def data(self):
        """
        Returns object typed bytes with the payload of the message.
        """
        return self._message.data()

    def value(self):
        """
        Returns object with the de-serialized version of the message content
        """
        return self._schema.decode(self._message.data())

    def properties(self):
        """
        Return the properties attached to the message. Properties are
        application-defined key/value pairs that will be attached to the
        message.
        """
        return self._message.properties()

    def partition_key(self):
        """
        Get the partitioning key for the message.
        """
        return self._message.partition_key()

    def publish_timestamp(self):
        """
        Get the timestamp in milliseconds with the message publish time.
        """
        return self._message.publish_timestamp()

    def event_timestamp(self):
        """
        Get the timestamp in milliseconds with the message event time.
        """
        return self._message.event_timestamp()

    def message_id(self):
        """
        The message ID that can be used to refere to this particular message.
        """
        return self._message.message_id()

    def topic_name(self):
        """
        Get the topic Name from which this message originated from
        """
        return self._message.topic_name()


class Authentication:
    """
    Authentication provider object. Used to load authentication from an external
    shared library.
    """
    def __init__(self, dynamicLibPath, authParamsString):
        """
        Create the authentication provider instance.

        **Args**

        * `dynamicLibPath`: Path to the authentication provider shared library
          (such as `tls.so`)
        * `authParamsString`: Comma-separated list of provider-specific
          configuration params
        """
        _check_type(str, dynamicLibPath, 'dynamicLibPath')
        _check_type(str, authParamsString, 'authParamsString')
        self.auth = _pulsar.Authentication(dynamicLibPath, authParamsString)


class AuthenticationTLS(Authentication):
    """
    TLS Authentication implementation
    """
    def __init__(self, certificate_path, private_key_path):
        """
        Create the TLS authentication provider instance.

        **Args**

        * `certificatePath`: Path to the public certificate
        * `privateKeyPath`: Path to private TLS key
        """
        _check_type(str, certificate_path, 'certificate_path')
        _check_type(str, private_key_path, 'private_key_path')
        self.auth = _pulsar.AuthenticationTLS(certificate_path, private_key_path)


class AuthenticationToken(Authentication):
    """
    Token based authentication implementation
    """
    def __init__(self, token):
        """
        Create the token authentication provider instance.

        **Args**

        * `token`: A string containing the token or a functions that provides a
                   string with the token
        """
        if not (isinstance(token, str) or callable(token)):
            raise ValueError("Argument token is expected to be of type 'str' or a function returning 'str'")
        self.auth = _pulsar.AuthenticationToken(token)


class AuthenticationAthenz(Authentication):
    """
    Athenz Authentication implementation
    """
    def __init__(self, auth_params_string):
        """
        Create the Athenz authentication provider instance.

        **Args**

        * `auth_params_string`: JSON encoded configuration for Athenz client
        """
        _check_type(str, auth_params_string, 'auth_params_string')
        self.auth = _pulsar.AuthenticationAthenz(auth_params_string)


class Client:
    """
    The Pulsar client. A single client instance can be used to create producers
    and consumers on multiple topics.

    The client will share the same connection pool and threads across all
    producers and consumers.
    """

    def __init__(self, service_url,
                 authentication=None,
                 operation_timeout_seconds=30,
                 io_threads=1,
                 message_listener_threads=1,
                 concurrent_lookup_requests=50000,
                 log_conf_file_path=None,
                 use_tls=False,
                 tls_trust_certs_file_path=None,
                 tls_allow_insecure_connection=False
                 ):
        """
        Create a new Pulsar client instance.

        **Args**

        * `service_url`: The Pulsar service url eg: pulsar://my-broker.com:6650/

        **Options**

        * `authentication`:
          Set the authentication provider to be used with the broker. For example:
          `AuthenticationTls` or `AuthenticationAthenz`
        * `operation_timeout_seconds`:
          Set timeout on client operations (subscribe, create producer, close,
          unsubscribe).
        * `io_threads`:
          Set the number of IO threads to be used by the Pulsar client.
        * `message_listener_threads`:
          Set the number of threads to be used by the Pulsar client when
          delivering messages through message listener. The default is 1 thread
          per Pulsar client. If using more than 1 thread, messages for distinct
          `message_listener`s will be delivered in different threads, however a
          single `MessageListener` will always be assigned to the same thread.
        * `concurrent_lookup_requests`:
          Number of concurrent lookup-requests allowed on each broker connection
          to prevent overload on the broker.
        * `log_conf_file_path`:
          Initialize log4cxx from a configuration file.
        * `use_tls`:
          Configure whether to use TLS encryption on the connection. This setting
          is deprecated. TLS will be automatically enabled if the `serviceUrl` is
          set to `pulsar+ssl://` or `https://`
        * `tls_trust_certs_file_path`:
          Set the path to the trusted TLS certificate file.
        * `tls_allow_insecure_connection`:
          Configure whether the Pulsar client accepts untrusted TLS certificates
          from the broker.
        """
        _check_type(str, service_url, 'service_url')
        _check_type_or_none(Authentication, authentication, 'authentication')
        _check_type(int, operation_timeout_seconds, 'operation_timeout_seconds')
        _check_type(int, io_threads, 'io_threads')
        _check_type(int, message_listener_threads, 'message_listener_threads')
        _check_type(int, concurrent_lookup_requests, 'concurrent_lookup_requests')
        _check_type_or_none(str, log_conf_file_path, 'log_conf_file_path')
        _check_type(bool, use_tls, 'use_tls')
        _check_type_or_none(str, tls_trust_certs_file_path, 'tls_trust_certs_file_path')
        _check_type(bool, tls_allow_insecure_connection, 'tls_allow_insecure_connection')

        conf = _pulsar.ClientConfiguration()
        if authentication:
            conf.authentication(authentication.auth)
        conf.operation_timeout_seconds(operation_timeout_seconds)
        conf.io_threads(io_threads)
        conf.message_listener_threads(message_listener_threads)
        conf.concurrent_lookup_requests(concurrent_lookup_requests)
        if log_conf_file_path:
            conf.log_conf_file_path(log_conf_file_path)
        if use_tls or service_url.startswith('pulsar+ssl://') or service_url.startswith('https://'):
            conf.use_tls(True)
        if tls_trust_certs_file_path:
            conf.tls_trust_certs_file_path(tls_trust_certs_file_path)
        conf.tls_allow_insecure_connection(tls_allow_insecure_connection)
        self._client = _pulsar.Client(service_url, conf)
        self._consumers = []

    def create_producer(self, topic,
                        producer_name=None,
                        schema=schema.BytesSchema(),
                        initial_sequence_id=None,
                        send_timeout_millis=30000,
                        compression_type=CompressionType.NONE,
                        max_pending_messages=1000,
                        max_pending_messages_across_partitions=50000,
                        block_if_queue_full=False,
                        batching_enabled=False,
                        batching_max_messages=1000,
                        batching_max_allowed_size_in_bytes=128*1024,
                        batching_max_publish_delay_ms=10,
                        message_routing_mode=PartitionsRoutingMode.RoundRobinDistribution,
                        properties=None,
                        ):
        """
        Create a new producer on a given topic.

        **Args**

        * `topic`:
          The topic name

        **Options**

        * `producer_name`:
           Specify a name for the producer. If not assigned,
           the system will generate a globally unique name which can be accessed
           with `Producer.producer_name()`. When specifying a name, it is app to
           the user to ensure that, for a given topic, the producer name is unique
           across all Pulsar's clusters.
        * `schema`:
           Define the schema of the data that will be published by this producer.
           The schema will be used for two purposes:
             - Validate the data format against the topic defined schema
             - Perform serialization/deserialization between data and objects
           An example for this parameter would be to pass `schema=JsonSchema(MyRecordClass)`.
        * `initial_sequence_id`:
           Set the baseline for the sequence ids for messages
           published by the producer. First message will be using
           `(initialSequenceId + 1)`` as its sequence id and subsequent messages will
           be assigned incremental sequence ids, if not otherwise specified.
        * `send_timeout_seconds`:
          If a message is not acknowledged by the server before the
          `send_timeout` expires, an error will be reported.
        * `compression_type`:
          Set the compression type for the producer. By default, message
          payloads are not compressed. Supported compression types are
          `CompressionType.LZ4`, `CompressionType.ZLib` and `CompressionType.ZSTD`.
          ZSTD is supported since Pulsar 2.3. Consumers will need to be at least at that
          release in order to be able to receive messages compressed with ZSTD.
        * `max_pending_messages`:
          Set the max size of the queue holding the messages pending to receive
          an acknowledgment from the broker.
        * `max_pending_messages_across_partitions`:
          Set the max size of the queue holding the messages pending to receive
          an acknowledgment across partitions from the broker.
        * `block_if_queue_full`: Set whether `send_async` operations should
          block when the outgoing message queue is full.
        * `message_routing_mode`:
          Set the message routing mode for the partitioned producer. Default is `PartitionsRoutingMode.RoundRobinDistribution`,
          other option is `PartitionsRoutingMode.UseSinglePartition`
        * `properties`:
          Sets the properties for the producer. The properties associated with a producer
          can be used for identify a producer at broker side.
        """
        _check_type(str, topic, 'topic')
        _check_type_or_none(str, producer_name, 'producer_name')
        _check_type(_schema.Schema, schema, 'schema')
        _check_type_or_none(int, initial_sequence_id, 'initial_sequence_id')
        _check_type(int, send_timeout_millis, 'send_timeout_millis')
        _check_type(CompressionType, compression_type, 'compression_type')
        _check_type(int, max_pending_messages, 'max_pending_messages')
        _check_type(int, max_pending_messages_across_partitions, 'max_pending_messages_across_partitions')
        _check_type(bool, block_if_queue_full, 'block_if_queue_full')
        _check_type(bool, batching_enabled, 'batching_enabled')
        _check_type(int, batching_max_messages, 'batching_max_messages')
        _check_type(int, batching_max_allowed_size_in_bytes, 'batching_max_allowed_size_in_bytes')
        _check_type(int, batching_max_publish_delay_ms, 'batching_max_publish_delay_ms')
        _check_type_or_none(dict, properties, 'properties')

        conf = _pulsar.ProducerConfiguration()
        conf.send_timeout_millis(send_timeout_millis)
        conf.compression_type(compression_type)
        conf.max_pending_messages(max_pending_messages)
        conf.max_pending_messages_across_partitions(max_pending_messages_across_partitions)
        conf.block_if_queue_full(block_if_queue_full)
        conf.batching_enabled(batching_enabled)
        conf.batching_max_messages(batching_max_messages)
        conf.batching_max_allowed_size_in_bytes(batching_max_allowed_size_in_bytes)
        conf.batching_max_publish_delay_ms(batching_max_publish_delay_ms)
        conf.partitions_routing_mode(message_routing_mode)
        if producer_name:
            conf.producer_name(producer_name)
        if initial_sequence_id:
            conf.initial_sequence_id(initial_sequence_id)
        if properties:
            for k, v in properties.items():
                conf.property(k, v)

        conf.schema(schema.schema_info())

        p = Producer()
        p._producer = self._client.create_producer(topic, conf)
        p._schema = schema
        return p

    def subscribe(self, topic, subscription_name,
                  consumer_type=ConsumerType.Exclusive,
                  schema=schema.BytesSchema(),
                  message_listener=None,
                  receiver_queue_size=1000,
                  max_total_receiver_queue_size_across_partitions=50000,
                  consumer_name=None,
                  unacked_messages_timeout_ms=None,
                  broker_consumer_stats_cache_time_ms=30000,
                  is_read_compacted=False,
                  properties=None,
                  pattern_auto_discovery_period=60,
                  initial_position=InitialPosition.Latest
                  ):
        """
        Subscribe to the given topic and subscription combination.

        **Args**

        * `topic`: The name of the topic, list of topics or regex pattern.
                  This method will accept these forms:
                    - `topic='my-topic'`
                    - `topic=['topic-1', 'topic-2', 'topic-3']`
                    - `topic=re.compile('topic-.*')`
        * `subscription`: The name of the subscription.

        **Options**

        * `consumer_type`:
          Select the subscription type to be used when subscribing to the topic.
        * `schema`:
           Define the schema of the data that will be received by this consumer.
        * `message_listener`:
          Sets a message listener for the consumer. When the listener is set,
          the application will receive messages through it. Calls to
          `consumer.receive()` will not be allowed. The listener function needs
          to accept (consumer, message), for example:

                #!python
                def my_listener(consumer, message):
                    # process message
                    consumer.acknowledge(message)

        * `receiver_queue_size`:
          Sets the size of the consumer receive queue. The consumer receive
          queue controls how many messages can be accumulated by the consumer
          before the application calls `receive()`. Using a higher value could
          potentially increase the consumer throughput at the expense of higher
          memory utilization. Setting the consumer queue size to zero decreases
          the throughput of the consumer by disabling pre-fetching of messages.
          This approach improves the message distribution on shared subscription
          by pushing messages only to those consumers that are ready to process
          them. Neither receive with timeout nor partitioned topics can be used
          if the consumer queue size is zero. The `receive()` function call
          should not be interrupted when the consumer queue size is zero. The
          default value is 1000 messages and should work well for most use
          cases.
        * `max_total_receiver_queue_size_across_partitions`
          Set the max total receiver queue size across partitions.
          This setting will be used to reduce the receiver queue size for individual partitions
        * `consumer_name`:
          Sets the consumer name.
        * `unacked_messages_timeout_ms`:
          Sets the timeout in milliseconds for unacknowledged messages. The
          timeout needs to be greater than 10 seconds. An exception is thrown if
          the given value is less than 10 seconds. If a successful
          acknowledgement is not sent within the timeout, all the unacknowledged
          messages are redelivered.
        * `broker_consumer_stats_cache_time_ms`:
          Sets the time duration for which the broker-side consumer stats will
          be cached in the client.
        * `properties`:
          Sets the properties for the consumer. The properties associated with a consumer
          can be used for identify a consumer at broker side.
        * `pattern_auto_discovery_period`:
          Periods of seconds for consumer to auto discover match topics.
        * `initial_position`:
          Set the initial position of a consumer  when subscribing to the topic.
          It could be either: `InitialPosition.Earliest` or `InitialPosition.Latest`.
          Default: `Latest`.
        """
        _check_type(str, subscription_name, 'subscription_name')
        _check_type(ConsumerType, consumer_type, 'consumer_type')
        _check_type(_schema.Schema, schema, 'schema')
        _check_type(int, receiver_queue_size, 'receiver_queue_size')
        _check_type(int, max_total_receiver_queue_size_across_partitions,
                    'max_total_receiver_queue_size_across_partitions')
        _check_type_or_none(str, consumer_name, 'consumer_name')
        _check_type_or_none(int, unacked_messages_timeout_ms, 'unacked_messages_timeout_ms')
        _check_type(int, broker_consumer_stats_cache_time_ms, 'broker_consumer_stats_cache_time_ms')
        _check_type(bool, is_read_compacted, 'is_read_compacted')
        _check_type_or_none(dict, properties, 'properties')
        _check_type(InitialPosition, initial_position, 'initial_position')

        conf = _pulsar.ConsumerConfiguration()
        conf.consumer_type(consumer_type)
        conf.read_compacted(is_read_compacted)
        if message_listener:
            conf.message_listener(_listener_wrapper(message_listener, schema))
        conf.receiver_queue_size(receiver_queue_size)
        conf.max_total_receiver_queue_size_across_partitions(max_total_receiver_queue_size_across_partitions)
        if consumer_name:
            conf.consumer_name(consumer_name)
        if unacked_messages_timeout_ms:
            conf.unacked_messages_timeout_ms(unacked_messages_timeout_ms)
        conf.broker_consumer_stats_cache_time_ms(broker_consumer_stats_cache_time_ms)
        if properties:
            for k, v in properties.items():
                conf.property(k, v)
        conf.subscription_initial_position(initial_position)

        conf.schema(schema.schema_info())

        c = Consumer()
        if isinstance(topic, str):
            # Single topic
            c._consumer = self._client.subscribe(topic, subscription_name, conf)
        elif isinstance(topic, list):
            # List of topics
            c._consumer = self._client.subscribe_topics(topic, subscription_name, conf)
        elif isinstance(topic, _retype):
            # Regex pattern
            c._consumer = self._client.subscribe_pattern(topic.pattern, subscription_name, conf)
        else:
            raise ValueError("Argument 'topic' is expected to be of a type between (str, list, re.pattern)")

        c._client = self
        c._schema = schema
        self._consumers.append(c)
        return c

    def create_reader(self, topic, start_message_id,
                      schema=schema.BytesSchema(),
                      reader_listener=None,
                      receiver_queue_size=1000,
                      reader_name=None,
                      subscription_role_prefix=None
                      ):
        """
        Create a reader on a particular topic

        **Args**

        * `topic`: The name of the topic.
        * `start_message_id`: The initial reader positioning is done by specifying a message id.
           The options are:
            * `MessageId.earliest`: Start reading from the earliest message available in the topic
            * `MessageId.latest`: Start reading from the end topic, only getting messages published
               after the reader was created
            * `MessageId`: When passing a particular message id, the reader will position itself on
               that specific position. The first message to be read will be the message next to the
               specified messageId. Message id can be serialized into a string and deserialized
               back into a `MessageId` object:

                   # Serialize to string
                   s = msg.message_id().serialize()

                   # Deserialize from string
                   msg_id = MessageId.deserialize(s)

        **Options**

        * `schema`:
           Define the schema of the data that will be received by this reader.
        * `reader_listener`:
          Sets a message listener for the reader. When the listener is set,
          the application will receive messages through it. Calls to
          `reader.read_next()` will not be allowed. The listener function needs
          to accept (reader, message), for example:

                def my_listener(reader, message):
                    # process message
                    pass

        * `receiver_queue_size`:
          Sets the size of the reader receive queue. The reader receive
          queue controls how many messages can be accumulated by the reader
          before the application calls `read_next()`. Using a higher value could
          potentially increase the reader throughput at the expense of higher
          memory utilization.
        * `reader_name`:
          Sets the reader name.
        * `subscription_role_prefix`:
          Sets the subscription role prefix.
        """
        _check_type(str, topic, 'topic')
        _check_type(_pulsar.MessageId, start_message_id, 'start_message_id')
        _check_type(_schema.Schema, schema, 'schema')
        _check_type(int, receiver_queue_size, 'receiver_queue_size')
        _check_type_or_none(str, reader_name, 'reader_name')
        _check_type_or_none(str, subscription_role_prefix, 'subscription_role_prefix')

        conf = _pulsar.ReaderConfiguration()
        if reader_listener:
            conf.reader_listener(_listener_wrapper(reader_listener, schema))
        conf.receiver_queue_size(receiver_queue_size)
        if reader_name:
            conf.reader_name(reader_name)
        if subscription_role_prefix:
            conf.subscription_role_prefix(subscription_role_prefix)
        conf.schema(schema.schema_info())

        c = Reader()
        c._reader = self._client.create_reader(topic, start_message_id, conf)
        c._client = self
        c._schema = schema
        self._consumers.append(c)
        return c

    def get_topic_partitions(self, topic):
        """
        Get the list of partitions for a given topic.

        If the topic is partitioned, this will return a list of partition names. If the topic is not
        partitioned, the returned list will contain the topic name itself.

        This can be used to discover the partitions and create Reader, Consumer or Producer
        instances directly on a particular partition.
        :param topic: the topic name to lookup
        :return: a list of partition name
        """
        _check_type(str, topic, 'topic')
        return self._client.get_topic_partitions(topic)

    def close(self):
        """
        Close the client and all the associated producers and consumers
        """
        self._client.close()


class Producer:
    """
    The Pulsar message producer, used to publish messages on a topic.
    """

    def topic(self):
        """
        Return the topic which producer is publishing to
        """
        return self._producer.topic()

    def producer_name(self):
        """
        Return the producer name which could have been assigned by the
        system or specified by the client
        """
        return self._producer.producer_name()

    def last_sequence_id(self):
        """
        Get the last sequence id that was published by this producer.

        This represent either the automatically assigned or custom sequence id
        (set on the `MessageBuilder`) that was published and acknowledged by the broker.

        After recreating a producer with the same producer name, this will return the
        last message that was published in the previous producer session, or -1 if
        there no message was ever published.
        """
        return self._producer.last_sequence_id()

    def send(self, content,
             properties=None,
             partition_key=None,
             sequence_id=None,
             replication_clusters=None,
             disable_replication=False,
             event_timestamp=None,
             ):
        """
        Publish a message on the topic. Blocks until the message is acknowledged

        **Args**

        * `content`:
          A `bytes` object with the message payload.

        **Options**

        * `properties`:
          A dict of application-defined string properties.
        * `partition_key`:
          Sets the partition key for message routing. A hash of this key is used
          to determine the message's topic partition.
        * `sequence_id`:
          Specify a custom sequence id for the message being published.
        * `replication_clusters`:
          Override namespace replication clusters. Note that it is the caller's
          responsibility to provide valid cluster names and that all clusters
          have been previously configured as topics. Given an empty list,
          the message will replicate according to the namespace configuration.
        * `disable_replication`:
          Do not replicate this message.
        * `event_timestamp`:
          Timestamp in millis of the timestamp of event creation
        """
        msg = self._build_msg(content, properties, partition_key, sequence_id,
                              replication_clusters, disable_replication, event_timestamp)
        return self._producer.send(msg)

    def send_async(self, content, callback,
                   properties=None,
                   partition_key=None,
                   sequence_id=None,
                   replication_clusters=None,
                   disable_replication=False,
                   event_timestamp=None
                   ):
        """
        Send a message asynchronously.

        The `callback` will be invoked once the message has been acknowledged
        by the broker.

        Example:

            #!python
            def callback(res, msg):
                print('Message published: %s' % res)

            producer.send_async(msg, callback)

        When the producer queue is full, by default the message will be rejected
        and the callback invoked with an error code.

        **Args**

        * `content`:
          A `bytes` object with the message payload.

        **Options**

        * `properties`:
          A dict of application0-defined string properties.
        * `partition_key`:
          Sets the partition key for the message routing. A hash of this key is
          used to determine the message's topic partition.
        * `sequence_id`:
          Specify a custom sequence id for the message being published.
        * `replication_clusters`: Override namespace replication clusters. Note
          that it is the caller's responsibility to provide valid cluster names
          and that all clusters have been previously configured as topics.
          Given an empty list, the message will replicate per the namespace
          configuration.
        * `disable_replication`:
          Do not replicate this message.
        * `event_timestamp`:
          Timestamp in millis of the timestamp of event creation
        """
        msg = self._build_msg(content, properties, partition_key, sequence_id,
                              replication_clusters, disable_replication, event_timestamp)
        self._producer.send_async(msg, callback)


    def flush(self):
        """
        Flush all the messages buffered in the client and wait until all messages have been
        successfully persisted
        """
        self._producer.flush()
        

    def close(self):
        """
        Close the producer.
        """
        self._producer.close()

    def _build_msg(self, content, properties, partition_key, sequence_id,
                   replication_clusters, disable_replication, event_timestamp):
        data = self._schema.encode(content)

        _check_type(bytes, data, 'data')
        _check_type_or_none(dict, properties, 'properties')
        _check_type_or_none(str, partition_key, 'partition_key')
        _check_type_or_none(int, sequence_id, 'sequence_id')
        _check_type_or_none(list, replication_clusters, 'replication_clusters')
        _check_type(bool, disable_replication, 'disable_replication')
        _check_type_or_none(int, event_timestamp, 'event_timestamp')

        mb = _pulsar.MessageBuilder()
        mb.content(data)
        if properties:
            for k, v in properties.items():
                mb.property(k, v)
        if partition_key:
            mb.partition_key(partition_key)
        if sequence_id:
            mb.sequence_id(sequence_id)
        if replication_clusters:
            mb.replication_clusters(replication_clusters)
        if disable_replication:
            mb.disable_replication(disable_replication)
        if event_timestamp:
            mb.event_timestamp(event_timestamp)
        return mb.build()


class Consumer:
    """
    Pulsar consumer.
    """

    def topic(self):
        """
        Return the topic this consumer is subscribed to.
        """
        return self._consumer.topic()

    def subscription_name(self):
        """
        Return the subscription name.
        """
        return self._consumer.subscription_name()

    def unsubscribe(self):
        """
        Unsubscribe the current consumer from the topic.

        This method will block until the operation is completed. Once the
        consumer is unsubscribed, no more messages will be received and
        subsequent new messages will not be retained for this consumer.

        This consumer object cannot be reused.
        """
        return self._consumer.unsubscribe()

    def receive(self, timeout_millis=None):
        """
        Receive a single message.

        If a message is not immediately available, this method will block until
        a new message is available.

        **Options**

        * `timeout_millis`:
          If specified, the receive will raise an exception if a message is not
          available within the timeout.
        """
        if timeout_millis is None:
            msg = self._consumer.receive()
        else:
            _check_type(int, timeout_millis, 'timeout_millis')
            msg = self._consumer.receive(timeout_millis)

        m = Message()
        m._message = msg
        m._schema = self._schema
        return m

    def acknowledge(self, message):
        """
        Acknowledge the reception of a single message.

        This method will block until an acknowledgement is sent to the broker.
        After that, the message will not be re-delivered to this consumer.

        **Args**

        * `message`:
          The received message or message id.
        """
        if isinstance(message, Message):
            self._consumer.acknowledge(message._message)
        else:
            self._consumer.acknowledge(message)

    def acknowledge_cumulative(self, message):
        """
        Acknowledge the reception of all the messages in the stream up to (and
        including) the provided message.

        This method will block until an acknowledgement is sent to the broker.
        After that, the messages will not be re-delivered to this consumer.

        **Args**

        * `message`:
          The received message or message id.
        """
        if isinstance(message, Message):
            self._consumer.acknowledge_cumulative(message._message)
        else:
            self._consumer.acknowledge_cumulative(message)

    def pause_message_listener(self):
        """
        Pause receiving messages via the `message_listener` until
        `resume_message_listener()` is called.
        """
        self._consumer.pause_message_listener()

    def resume_message_listener(self):
        """
        Resume receiving the messages via the message listener.
        Asynchronously receive all the messages enqueued from the time
        `pause_message_listener()` was called.
        """
        self._consumer.resume_message_listener()

    def redeliver_unacknowledged_messages(self):
        """
        Redelivers all the unacknowledged messages. In failover mode, the
        request is ignored if the consumer is not active for the given topic. In
        shared mode, the consumer's messages to be redelivered are distributed
        across all the connected consumers. This is a non-blocking call and
        doesn't throw an exception. In case the connection breaks, the messages
        are redelivered after reconnect.
        """
        self._consumer.redeliver_unacknowledged_messages()

    def seek(self, messageid):
        """
        Reset the subscription associated with this consumer to a specific message id.
        The message id can either be a specific message or represent the first or last messages in the topic.
        Note: this operation can only be done on non-partitioned topics. For these, one can rather perform the
        seek() on the individual partitions.

        **Args**

        * `message`:
          The message id for seek.
        """
        self._consumer.seek(messageid)

    def close(self):
        """
        Close the consumer.
        """
        self._consumer.close()
        self._client._consumers.remove(self)


class Reader:
    """
    Pulsar topic reader.
    """

    def topic(self):
        """
        Return the topic this reader is reading from.
        """
        return self._reader.topic()

    def read_next(self, timeout_millis=None):
        """
        Read a single message.

        If a message is not immediately available, this method will block until
        a new message is available.

        **Options**

        * `timeout_millis`:
          If specified, the receive will raise an exception if a message is not
          available within the timeout.
        """
        if timeout_millis is None:
            msg = self._reader.read_next()
        else:
            _check_type(int, timeout_millis, 'timeout_millis')
            msg = self._reader.read_next(timeout_millis)

        m = Message()
        m._message = msg
        m._schema = self._schema
        return m

    def has_message_available(self):
        """
        Check if there is any message available to read from the current position.
        """
        return self._reader.has_message_available();

    def close(self):
        """
        Close the reader.
        """
        self._reader.close()
        self._client._consumers.remove(self)


def _check_type(var_type, var, name):
    if not isinstance(var, var_type):
        raise ValueError("Argument %s is expected to be of type '%s' and not '%s'"
                         % (name, var_type.__name__, type(var).__name__))


def _check_type_or_none(var_type, var, name):
    if var is not None and not isinstance(var, var_type):
        raise ValueError("Argument %s is expected to be either None or of type '%s'"
                         % (name, var_type.__name__))


def _listener_wrapper(listener, schema):
    def wrapper(consumer, msg):
        c = Consumer()
        c._consumer = consumer
        m = Message()
        m._message = msg
        m._schema = schema
        listener(c, m)
    return wrapper

Sub-modules

pulsar.functions

pulsar.schema

Classes

class Authentication (dynamicLibPath, authParamsString)

Authentication provider object. Used to load authentication from an external shared library.

Create the authentication provider instance.

Args

• dynamicLibPath: Path to the authentication provider shared library (such as tls.so)
• authParamsString: Comma-separated list of provider-specific configuration params

Expand source code

class Authentication:
    """
    Authentication provider object. Used to load authentication from an external
    shared library.
    """
    def __init__(self, dynamicLibPath, authParamsString):
        """
        Create the authentication provider instance.

        **Args**

        * `dynamicLibPath`: Path to the authentication provider shared library
          (such as `tls.so`)
        * `authParamsString`: Comma-separated list of provider-specific
          configuration params
        """
        _check_type(str, dynamicLibPath, 'dynamicLibPath')
        _check_type(str, authParamsString, 'authParamsString')
        self.auth = _pulsar.Authentication(dynamicLibPath, authParamsString)

Subclasses

• AuthenticationTLS
• AuthenticationToken
• AuthenticationAthenz

class AuthenticationAthenz (auth_params_string)

Athenz Authentication implementation

Create the Athenz authentication provider instance.

Args

• auth_params_string: JSON encoded configuration for Athenz client

Expand source code

class AuthenticationAthenz(Authentication):
    """
    Athenz Authentication implementation
    """
    def __init__(self, auth_params_string):
        """
        Create the Athenz authentication provider instance.

        **Args**

        * `auth_params_string`: JSON encoded configuration for Athenz client
        """
        _check_type(str, auth_params_string, 'auth_params_string')
        self.auth = _pulsar.AuthenticationAthenz(auth_params_string)

Ancestors

• Authentication

class AuthenticationTLS (certificate_path, private_key_path)

TLS Authentication implementation

Create the TLS authentication provider instance.

Args

• certificatePath: Path to the public certificate
• privateKeyPath: Path to private TLS key

Expand source code

class AuthenticationTLS(Authentication):
    """
    TLS Authentication implementation
    """
    def __init__(self, certificate_path, private_key_path):
        """
        Create the TLS authentication provider instance.

        **Args**

        * `certificatePath`: Path to the public certificate
        * `privateKeyPath`: Path to private TLS key
        """
        _check_type(str, certificate_path, 'certificate_path')
        _check_type(str, private_key_path, 'private_key_path')
        self.auth = _pulsar.AuthenticationTLS(certificate_path, private_key_path)

Ancestors

• Authentication

class AuthenticationToken (token)

Token based authentication implementation

Create the token authentication provider instance.

Args

• token: A string containing the token or a functions that provides a string with the token

Expand source code

class AuthenticationToken(Authentication):
    """
    Token based authentication implementation
    """
    def __init__(self, token):
        """
        Create the token authentication provider instance.

        **Args**

        * `token`: A string containing the token or a functions that provides a
                   string with the token
        """
        if not (isinstance(token, str) or callable(token)):
            raise ValueError("Argument token is expected to be of type 'str' or a function returning 'str'")
        self.auth = _pulsar.AuthenticationToken(token)

Ancestors

• Authentication

class Client (service_url, authentication=None, operation_timeout_seconds=30, io_threads=1, message_listener_threads=1, concurrent_lookup_requests=50000, log_conf_file_path=None, use_tls=False, tls_trust_certs_file_path=None, tls_allow_insecure_connection=False)

The Pulsar client. A single client instance can be used to create producers and consumers on multiple topics.

The client will share the same connection pool and threads across all producers and consumers.

Create a new Pulsar client instance.

Args

• service_url: The Pulsar service url eg: pulsar://my-broker.com:6650/

Options

• authentication: Set the authentication provider to be used with the broker. For example: AuthenticationTls or AuthenticationAthenz
• operation_timeout_seconds: Set timeout on client operations (subscribe, create producer, close, unsubscribe).
• io_threads: Set the number of IO threads to be used by the Pulsar client.
• message_listener_threads: Set the number of threads to be used by the Pulsar client when delivering messages through message listener. The default is 1 thread per Pulsar client. If using more than 1 thread, messages for distinct message_listeners will be delivered in different threads, however a single MessageListener will always be assigned to the same thread.
• concurrent_lookup_requests: Number of concurrent lookup-requests allowed on each broker connection to prevent overload on the broker.
• log_conf_file_path: Initialize log4cxx from a configuration file.
• use_tls: Configure whether to use TLS encryption on the connection. This setting is deprecated. TLS will be automatically enabled if the serviceUrl is set to pulsar+ssl:// or <https://>
• tls_trust_certs_file_path: Set the path to the trusted TLS certificate file.
• tls_allow_insecure_connection: Configure whether the Pulsar client accepts untrusted TLS certificates from the broker.

Expand source code

class Client:
    """
    The Pulsar client. A single client instance can be used to create producers
    and consumers on multiple topics.

    The client will share the same connection pool and threads across all
    producers and consumers.
    """

    def __init__(self, service_url,
                 authentication=None,
                 operation_timeout_seconds=30,
                 io_threads=1,
                 message_listener_threads=1,
                 concurrent_lookup_requests=50000,
                 log_conf_file_path=None,
                 use_tls=False,
                 tls_trust_certs_file_path=None,
                 tls_allow_insecure_connection=False
                 ):
        """
        Create a new Pulsar client instance.

        **Args**

        * `service_url`: The Pulsar service url eg: pulsar://my-broker.com:6650/

        **Options**

        * `authentication`:
          Set the authentication provider to be used with the broker. For example:
          `AuthenticationTls` or `AuthenticationAthenz`
        * `operation_timeout_seconds`:
          Set timeout on client operations (subscribe, create producer, close,
          unsubscribe).
        * `io_threads`:
          Set the number of IO threads to be used by the Pulsar client.
        * `message_listener_threads`:
          Set the number of threads to be used by the Pulsar client when
          delivering messages through message listener. The default is 1 thread
          per Pulsar client. If using more than 1 thread, messages for distinct
          `message_listener`s will be delivered in different threads, however a
          single `MessageListener` will always be assigned to the same thread.
        * `concurrent_lookup_requests`:
          Number of concurrent lookup-requests allowed on each broker connection
          to prevent overload on the broker.
        * `log_conf_file_path`:
          Initialize log4cxx from a configuration file.
        * `use_tls`:
          Configure whether to use TLS encryption on the connection. This setting
          is deprecated. TLS will be automatically enabled if the `serviceUrl` is
          set to `pulsar+ssl://` or `https://`
        * `tls_trust_certs_file_path`:
          Set the path to the trusted TLS certificate file.
        * `tls_allow_insecure_connection`:
          Configure whether the Pulsar client accepts untrusted TLS certificates
          from the broker.
        """
        _check_type(str, service_url, 'service_url')
        _check_type_or_none(Authentication, authentication, 'authentication')
        _check_type(int, operation_timeout_seconds, 'operation_timeout_seconds')
        _check_type(int, io_threads, 'io_threads')
        _check_type(int, message_listener_threads, 'message_listener_threads')
        _check_type(int, concurrent_lookup_requests, 'concurrent_lookup_requests')
        _check_type_or_none(str, log_conf_file_path, 'log_conf_file_path')
        _check_type(bool, use_tls, 'use_tls')
        _check_type_or_none(str, tls_trust_certs_file_path, 'tls_trust_certs_file_path')
        _check_type(bool, tls_allow_insecure_connection, 'tls_allow_insecure_connection')

        conf = _pulsar.ClientConfiguration()
        if authentication:
            conf.authentication(authentication.auth)
        conf.operation_timeout_seconds(operation_timeout_seconds)
        conf.io_threads(io_threads)
        conf.message_listener_threads(message_listener_threads)
        conf.concurrent_lookup_requests(concurrent_lookup_requests)
        if log_conf_file_path:
            conf.log_conf_file_path(log_conf_file_path)
        if use_tls or service_url.startswith('pulsar+ssl://') or service_url.startswith('https://'):
            conf.use_tls(True)
        if tls_trust_certs_file_path:
            conf.tls_trust_certs_file_path(tls_trust_certs_file_path)
        conf.tls_allow_insecure_connection(tls_allow_insecure_connection)
        self._client = _pulsar.Client(service_url, conf)
        self._consumers = []

    def create_producer(self, topic,
                        producer_name=None,
                        schema=schema.BytesSchema(),
                        initial_sequence_id=None,
                        send_timeout_millis=30000,
                        compression_type=CompressionType.NONE,
                        max_pending_messages=1000,
                        max_pending_messages_across_partitions=50000,
                        block_if_queue_full=False,
                        batching_enabled=False,
                        batching_max_messages=1000,
                        batching_max_allowed_size_in_bytes=128*1024,
                        batching_max_publish_delay_ms=10,
                        message_routing_mode=PartitionsRoutingMode.RoundRobinDistribution,
                        properties=None,
                        ):
        """
        Create a new producer on a given topic.

        **Args**

        * `topic`:
          The topic name

        **Options**

        * `producer_name`:
           Specify a name for the producer. If not assigned,
           the system will generate a globally unique name which can be accessed
           with `Producer.producer_name()`. When specifying a name, it is app to
           the user to ensure that, for a given topic, the producer name is unique
           across all Pulsar's clusters.
        * `schema`:
           Define the schema of the data that will be published by this producer.
           The schema will be used for two purposes:
             - Validate the data format against the topic defined schema
             - Perform serialization/deserialization between data and objects
           An example for this parameter would be to pass `schema=JsonSchema(MyRecordClass)`.
        * `initial_sequence_id`:
           Set the baseline for the sequence ids for messages
           published by the producer. First message will be using
           `(initialSequenceId + 1)`` as its sequence id and subsequent messages will
           be assigned incremental sequence ids, if not otherwise specified.
        * `send_timeout_seconds`:
          If a message is not acknowledged by the server before the
          `send_timeout` expires, an error will be reported.
        * `compression_type`:
          Set the compression type for the producer. By default, message
          payloads are not compressed. Supported compression types are
          `CompressionType.LZ4`, `CompressionType.ZLib` and `CompressionType.ZSTD`.
          ZSTD is supported since Pulsar 2.3. Consumers will need to be at least at that
          release in order to be able to receive messages compressed with ZSTD.
        * `max_pending_messages`:
          Set the max size of the queue holding the messages pending to receive
          an acknowledgment from the broker.
        * `max_pending_messages_across_partitions`:
          Set the max size of the queue holding the messages pending to receive
          an acknowledgment across partitions from the broker.
        * `block_if_queue_full`: Set whether `send_async` operations should
          block when the outgoing message queue is full.
        * `message_routing_mode`:
          Set the message routing mode for the partitioned producer. Default is `PartitionsRoutingMode.RoundRobinDistribution`,
          other option is `PartitionsRoutingMode.UseSinglePartition`
        * `properties`:
          Sets the properties for the producer. The properties associated with a producer
          can be used for identify a producer at broker side.
        """
        _check_type(str, topic, 'topic')
        _check_type_or_none(str, producer_name, 'producer_name')
        _check_type(_schema.Schema, schema, 'schema')
        _check_type_or_none(int, initial_sequence_id, 'initial_sequence_id')
        _check_type(int, send_timeout_millis, 'send_timeout_millis')
        _check_type(CompressionType, compression_type, 'compression_type')
        _check_type(int, max_pending_messages, 'max_pending_messages')
        _check_type(int, max_pending_messages_across_partitions, 'max_pending_messages_across_partitions')
        _check_type(bool, block_if_queue_full, 'block_if_queue_full')
        _check_type(bool, batching_enabled, 'batching_enabled')
        _check_type(int, batching_max_messages, 'batching_max_messages')
        _check_type(int, batching_max_allowed_size_in_bytes, 'batching_max_allowed_size_in_bytes')
        _check_type(int, batching_max_publish_delay_ms, 'batching_max_publish_delay_ms')
        _check_type_or_none(dict, properties, 'properties')

        conf = _pulsar.ProducerConfiguration()
        conf.send_timeout_millis(send_timeout_millis)
        conf.compression_type(compression_type)
        conf.max_pending_messages(max_pending_messages)
        conf.max_pending_messages_across_partitions(max_pending_messages_across_partitions)
        conf.block_if_queue_full(block_if_queue_full)
        conf.batching_enabled(batching_enabled)
        conf.batching_max_messages(batching_max_messages)
        conf.batching_max_allowed_size_in_bytes(batching_max_allowed_size_in_bytes)
        conf.batching_max_publish_delay_ms(batching_max_publish_delay_ms)
        conf.partitions_routing_mode(message_routing_mode)
        if producer_name:
            conf.producer_name(producer_name)
        if initial_sequence_id:
            conf.initial_sequence_id(initial_sequence_id)
        if properties:
            for k, v in properties.items():
                conf.property(k, v)

        conf.schema(schema.schema_info())

        p = Producer()
        p._producer = self._client.create_producer(topic, conf)
        p._schema = schema
        return p

    def subscribe(self, topic, subscription_name,
                  consumer_type=ConsumerType.Exclusive,
                  schema=schema.BytesSchema(),
                  message_listener=None,
                  receiver_queue_size=1000,
                  max_total_receiver_queue_size_across_partitions=50000,
                  consumer_name=None,
                  unacked_messages_timeout_ms=None,
                  broker_consumer_stats_cache_time_ms=30000,
                  is_read_compacted=False,
                  properties=None,
                  pattern_auto_discovery_period=60,
                  initial_position=InitialPosition.Latest
                  ):
        """
        Subscribe to the given topic and subscription combination.

        **Args**

        * `topic`: The name of the topic, list of topics or regex pattern.
                  This method will accept these forms:
                    - `topic='my-topic'`
                    - `topic=['topic-1', 'topic-2', 'topic-3']`
                    - `topic=re.compile('topic-.*')`
        * `subscription`: The name of the subscription.

        **Options**

        * `consumer_type`:
          Select the subscription type to be used when subscribing to the topic.
        * `schema`:
           Define the schema of the data that will be received by this consumer.
        * `message_listener`:
          Sets a message listener for the consumer. When the listener is set,
          the application will receive messages through it. Calls to
          `consumer.receive()` will not be allowed. The listener function needs
          to accept (consumer, message), for example:

                #!python
                def my_listener(consumer, message):
                    # process message
                    consumer.acknowledge(message)

        * `receiver_queue_size`:
          Sets the size of the consumer receive queue. The consumer receive
          queue controls how many messages can be accumulated by the consumer
          before the application calls `receive()`. Using a higher value could
          potentially increase the consumer throughput at the expense of higher
          memory utilization. Setting the consumer queue size to zero decreases
          the throughput of the consumer by disabling pre-fetching of messages.
          This approach improves the message distribution on shared subscription
          by pushing messages only to those consumers that are ready to process
          them. Neither receive with timeout nor partitioned topics can be used
          if the consumer queue size is zero. The `receive()` function call
          should not be interrupted when the consumer queue size is zero. The
          default value is 1000 messages and should work well for most use
          cases.
        * `max_total_receiver_queue_size_across_partitions`
          Set the max total receiver queue size across partitions.
          This setting will be used to reduce the receiver queue size for individual partitions
        * `consumer_name`:
          Sets the consumer name.
        * `unacked_messages_timeout_ms`:
          Sets the timeout in milliseconds for unacknowledged messages. The
          timeout needs to be greater than 10 seconds. An exception is thrown if
          the given value is less than 10 seconds. If a successful
          acknowledgement is not sent within the timeout, all the unacknowledged
          messages are redelivered.
        * `broker_consumer_stats_cache_time_ms`:
          Sets the time duration for which the broker-side consumer stats will
          be cached in the client.
        * `properties`:
          Sets the properties for the consumer. The properties associated with a consumer
          can be used for identify a consumer at broker side.
        * `pattern_auto_discovery_period`:
          Periods of seconds for consumer to auto discover match topics.
        * `initial_position`:
          Set the initial position of a consumer  when subscribing to the topic.
          It could be either: `InitialPosition.Earliest` or `InitialPosition.Latest`.
          Default: `Latest`.
        """
        _check_type(str, subscription_name, 'subscription_name')
        _check_type(ConsumerType, consumer_type, 'consumer_type')
        _check_type(_schema.Schema, schema, 'schema')
        _check_type(int, receiver_queue_size, 'receiver_queue_size')
        _check_type(int, max_total_receiver_queue_size_across_partitions,
                    'max_total_receiver_queue_size_across_partitions')
        _check_type_or_none(str, consumer_name, 'consumer_name')
        _check_type_or_none(int, unacked_messages_timeout_ms, 'unacked_messages_timeout_ms')
        _check_type(int, broker_consumer_stats_cache_time_ms, 'broker_consumer_stats_cache_time_ms')
        _check_type(bool, is_read_compacted, 'is_read_compacted')
        _check_type_or_none(dict, properties, 'properties')
        _check_type(InitialPosition, initial_position, 'initial_position')

        conf = _pulsar.ConsumerConfiguration()
        conf.consumer_type(consumer_type)
        conf.read_compacted(is_read_compacted)
        if message_listener:
            conf.message_listener(_listener_wrapper(message_listener, schema))
        conf.receiver_queue_size(receiver_queue_size)
        conf.max_total_receiver_queue_size_across_partitions(max_total_receiver_queue_size_across_partitions)
        if consumer_name:
            conf.consumer_name(consumer_name)
        if unacked_messages_timeout_ms:
            conf.unacked_messages_timeout_ms(unacked_messages_timeout_ms)
        conf.broker_consumer_stats_cache_time_ms(broker_consumer_stats_cache_time_ms)
        if properties:
            for k, v in properties.items():
                conf.property(k, v)
        conf.subscription_initial_position(initial_position)

        conf.schema(schema.schema_info())

        c = Consumer()
        if isinstance(topic, str):
            # Single topic
            c._consumer = self._client.subscribe(topic, subscription_name, conf)
        elif isinstance(topic, list):
            # List of topics
            c._consumer = self._client.subscribe_topics(topic, subscription_name, conf)
        elif isinstance(topic, _retype):
            # Regex pattern
            c._consumer = self._client.subscribe_pattern(topic.pattern, subscription_name, conf)
        else:
            raise ValueError("Argument 'topic' is expected to be of a type between (str, list, re.pattern)")

        c._client = self
        c._schema = schema
        self._consumers.append(c)
        return c

    def create_reader(self, topic, start_message_id,
                      schema=schema.BytesSchema(),
                      reader_listener=None,
                      receiver_queue_size=1000,
                      reader_name=None,
                      subscription_role_prefix=None
                      ):
        """
        Create a reader on a particular topic

        **Args**

        * `topic`: The name of the topic.
        * `start_message_id`: The initial reader positioning is done by specifying a message id.
           The options are:
            * `MessageId.earliest`: Start reading from the earliest message available in the topic
            * `MessageId.latest`: Start reading from the end topic, only getting messages published
               after the reader was created
            * `MessageId`: When passing a particular message id, the reader will position itself on
               that specific position. The first message to be read will be the message next to the
               specified messageId. Message id can be serialized into a string and deserialized
               back into a `MessageId` object:

                   # Serialize to string
                   s = msg.message_id().serialize()

                   # Deserialize from string
                   msg_id = MessageId.deserialize(s)

        **Options**

        * `schema`:
           Define the schema of the data that will be received by this reader.
        * `reader_listener`:
          Sets a message listener for the reader. When the listener is set,
          the application will receive messages through it. Calls to
          `reader.read_next()` will not be allowed. The listener function needs
          to accept (reader, message), for example:

                def my_listener(reader, message):
                    # process message
                    pass

        * `receiver_queue_size`:
          Sets the size of the reader receive queue. The reader receive
          queue controls how many messages can be accumulated by the reader
          before the application calls `read_next()`. Using a higher value could
          potentially increase the reader throughput at the expense of higher
          memory utilization.
        * `reader_name`:
          Sets the reader name.
        * `subscription_role_prefix`:
          Sets the subscription role prefix.
        """
        _check_type(str, topic, 'topic')
        _check_type(_pulsar.MessageId, start_message_id, 'start_message_id')
        _check_type(_schema.Schema, schema, 'schema')
        _check_type(int, receiver_queue_size, 'receiver_queue_size')
        _check_type_or_none(str, reader_name, 'reader_name')
        _check_type_or_none(str, subscription_role_prefix, 'subscription_role_prefix')

        conf = _pulsar.ReaderConfiguration()
        if reader_listener:
            conf.reader_listener(_listener_wrapper(reader_listener, schema))
        conf.receiver_queue_size(receiver_queue_size)
        if reader_name:
            conf.reader_name(reader_name)
        if subscription_role_prefix:
            conf.subscription_role_prefix(subscription_role_prefix)
        conf.schema(schema.schema_info())

        c = Reader()
        c._reader = self._client.create_reader(topic, start_message_id, conf)
        c._client = self
        c._schema = schema
        self._consumers.append(c)
        return c

    def get_topic_partitions(self, topic):
        """
        Get the list of partitions for a given topic.

        If the topic is partitioned, this will return a list of partition names. If the topic is not
        partitioned, the returned list will contain the topic name itself.

        This can be used to discover the partitions and create Reader, Consumer or Producer
        instances directly on a particular partition.
        :param topic: the topic name to lookup
        :return: a list of partition name
        """
        _check_type(str, topic, 'topic')
        return self._client.get_topic_partitions(topic)

    def close(self):
        """
        Close the client and all the associated producers and consumers
        """
        self._client.close()

Methods

def close(self)

Close the client and all the associated producers and consumers

Expand source code

def close(self):
    """
    Close the client and all the associated producers and consumers
    """
    self._client.close()

def create_producer(self, topic, producer_name=None, schema=<pulsar.schema.schema.BytesSchema object>, initial_sequence_id=None, send_timeout_millis=30000, compression_type=_pulsar.CompressionType.NONE, max_pending_messages=1000, max_pending_messages_across_partitions=50000, block_if_queue_full=False, batching_enabled=False, batching_max_messages=1000, batching_max_allowed_size_in_bytes=131072, batching_max_publish_delay_ms=10, message_routing_mode=_pulsar.PartitionsRoutingMode.RoundRobinDistribution, properties=None)

Create a new producer on a given topic.

Args

• topic: The topic name

Options

• producer_name: Specify a name for the producer. If not assigned, the system will generate a globally unique name which can be accessed with Producer.producer_name(). When specifying a name, it is app to the user to ensure that, for a given topic, the producer name is unique across all Pulsar's clusters.
• pulsar.schema: Define the schema of the data that will be published by this producer. The schema will be used for two purposes:
  • Validate the data format against the topic defined schema
  • Perform serialization/deserialization between data and objects An example for this parameter would be to pass schema=JsonSchema(MyRecordClass).
• initial_sequence_id: Set the baseline for the sequence ids for messages published by the producer. First message will be using `(initialSequenceId + 1)`` as its sequence id and subsequent messages will be assigned incremental sequence ids, if not otherwise specified.
• send_timeout_seconds: If a message is not acknowledged by the server before the send_timeout expires, an error will be reported.
• compression_type: Set the compression type for the producer. By default, message payloads are not compressed. Supported compression types are CompressionType.LZ4, CompressionType.ZLib and CompressionType.ZSTD. ZSTD is supported since Pulsar 2.3. Consumers will need to be at least at that release in order to be able to receive messages compressed with ZSTD.
• max_pending_messages: Set the max size of the queue holding the messages pending to receive an acknowledgment from the broker.
• max_pending_messages_across_partitions: Set the max size of the queue holding the messages pending to receive an acknowledgment across partitions from the broker.
• block_if_queue_full: Set whether send_async operations should block when the outgoing message queue is full.
• message_routing_mode: Set the message routing mode for the partitioned producer. Default is PartitionsRoutingMode.RoundRobinDistribution, other option is PartitionsRoutingMode.UseSinglePartition
• properties: Sets the properties for the producer. The properties associated with a producer can be used for identify a producer at broker side.

Expand source code

def create_producer(self, topic,
                    producer_name=None,
                    schema=schema.BytesSchema(),
                    initial_sequence_id=None,
                    send_timeout_millis=30000,
                    compression_type=CompressionType.NONE,
                    max_pending_messages=1000,
                    max_pending_messages_across_partitions=50000,
                    block_if_queue_full=False,
                    batching_enabled=False,
                    batching_max_messages=1000,
                    batching_max_allowed_size_in_bytes=128*1024,
                    batching_max_publish_delay_ms=10,
                    message_routing_mode=PartitionsRoutingMode.RoundRobinDistribution,
                    properties=None,
                    ):
    """
    Create a new producer on a given topic.

    **Args**

    * `topic`:
      The topic name

    **Options**

    * `producer_name`:
       Specify a name for the producer. If not assigned,
       the system will generate a globally unique name which can be accessed
       with `Producer.producer_name()`. When specifying a name, it is app to
       the user to ensure that, for a given topic, the producer name is unique
       across all Pulsar's clusters.
    * `schema`:
       Define the schema of the data that will be published by this producer.
       The schema will be used for two purposes:
         - Validate the data format against the topic defined schema
         - Perform serialization/deserialization between data and objects
       An example for this parameter would be to pass `schema=JsonSchema(MyRecordClass)`.
    * `initial_sequence_id`:
       Set the baseline for the sequence ids for messages
       published by the producer. First message will be using
       `(initialSequenceId + 1)`` as its sequence id and subsequent messages will
       be assigned incremental sequence ids, if not otherwise specified.
    * `send_timeout_seconds`:
      If a message is not acknowledged by the server before the
      `send_timeout` expires, an error will be reported.
    * `compression_type`:
      Set the compression type for the producer. By default, message
      payloads are not compressed. Supported compression types are
      `CompressionType.LZ4`, `CompressionType.ZLib` and `CompressionType.ZSTD`.
      ZSTD is supported since Pulsar 2.3. Consumers will need to be at least at that
      release in order to be able to receive messages compressed with ZSTD.
    * `max_pending_messages`:
      Set the max size of the queue holding the messages pending to receive
      an acknowledgment from the broker.
    * `max_pending_messages_across_partitions`:
      Set the max size of the queue holding the messages pending to receive
      an acknowledgment across partitions from the broker.
    * `block_if_queue_full`: Set whether `send_async` operations should
      block when the outgoing message queue is full.
    * `message_routing_mode`:
      Set the message routing mode for the partitioned producer. Default is `PartitionsRoutingMode.RoundRobinDistribution`,
      other option is `PartitionsRoutingMode.UseSinglePartition`
    * `properties`:
      Sets the properties for the producer. The properties associated with a producer
      can be used for identify a producer at broker side.
    """
    _check_type(str, topic, 'topic')
    _check_type_or_none(str, producer_name, 'producer_name')
    _check_type(_schema.Schema, schema, 'schema')
    _check_type_or_none(int, initial_sequence_id, 'initial_sequence_id')
    _check_type(int, send_timeout_millis, 'send_timeout_millis')
    _check_type(CompressionType, compression_type, 'compression_type')
    _check_type(int, max_pending_messages, 'max_pending_messages')
    _check_type(int, max_pending_messages_across_partitions, 'max_pending_messages_across_partitions')
    _check_type(bool, block_if_queue_full, 'block_if_queue_full')
    _check_type(bool, batching_enabled, 'batching_enabled')
    _check_type(int, batching_max_messages, 'batching_max_messages')
    _check_type(int, batching_max_allowed_size_in_bytes, 'batching_max_allowed_size_in_bytes')
    _check_type(int, batching_max_publish_delay_ms, 'batching_max_publish_delay_ms')
    _check_type_or_none(dict, properties, 'properties')

    conf = _pulsar.ProducerConfiguration()
    conf.send_timeout_millis(send_timeout_millis)
    conf.compression_type(compression_type)
    conf.max_pending_messages(max_pending_messages)
    conf.max_pending_messages_across_partitions(max_pending_messages_across_partitions)
    conf.block_if_queue_full(block_if_queue_full)
    conf.batching_enabled(batching_enabled)
    conf.batching_max_messages(batching_max_messages)
    conf.batching_max_allowed_size_in_bytes(batching_max_allowed_size_in_bytes)
    conf.batching_max_publish_delay_ms(batching_max_publish_delay_ms)
    conf.partitions_routing_mode(message_routing_mode)
    if producer_name:
        conf.producer_name(producer_name)
    if initial_sequence_id:
        conf.initial_sequence_id(initial_sequence_id)
    if properties:
        for k, v in properties.items():
            conf.property(k, v)

    conf.schema(schema.schema_info())

    p = Producer()
    p._producer = self._client.create_producer(topic, conf)
    p._schema = schema
    return p

def create_reader(self, topic, start_message_id, schema=<pulsar.schema.schema.BytesSchema object>, reader_listener=None, receiver_queue_size=1000, reader_name=None, subscription_role_prefix=None)

Create a reader on a particular topic

Args

• topic: The name of the topic.
• start_message_id: The initial reader positioning is done by specifying a message id. The options are:
  • MessageId.earliest: Start reading from the earliest message available in the topic
  • MessageId.latest: Start reading from the end topic, only getting messages published after the reader was created

  • MessageId: When passing a particular message id, the reader will position itself on that specific position. The first message to be read will be the message next to the specified messageId. Message id can be serialized into a string and deserialized back into a MessageId object:

    # Serialize to string s = msg.message_id().serialize()

    # Deserialize from string msg_id = MessageId.deserialize(s)

Options

• pulsar.schema: Define the schema of the data that will be received by this reader.

• reader_listener: Sets a message listener for the reader. When the listener is set, the application will receive messages through it. Calls to reader.read_next() will not be allowed. The listener function needs to accept (reader, message), for example:

  def my_listener(reader, message):
      # process message
      pass
  

• receiver_queue_size: Sets the size of the reader receive queue. The reader receive queue controls how many messages can be accumulated by the reader before the application calls read_next(). Using a higher value could potentially increase the reader throughput at the expense of higher memory utilization.

• reader_name: Sets the reader name.
• subscription_role_prefix: Sets the subscription role prefix.

Expand source code

def create_reader(self, topic, start_message_id,
                  schema=schema.BytesSchema(),
                  reader_listener=None,
                  receiver_queue_size=1000,
                  reader_name=None,
                  subscription_role_prefix=None
                  ):
    """
    Create a reader on a particular topic

    **Args**

    * `topic`: The name of the topic.
    * `start_message_id`: The initial reader positioning is done by specifying a message id.
       The options are:
        * `MessageId.earliest`: Start reading from the earliest message available in the topic
        * `MessageId.latest`: Start reading from the end topic, only getting messages published
           after the reader was created
        * `MessageId`: When passing a particular message id, the reader will position itself on
           that specific position. The first message to be read will be the message next to the
           specified messageId. Message id can be serialized into a string and deserialized
           back into a `MessageId` object:

               # Serialize to string
               s = msg.message_id().serialize()

               # Deserialize from string
               msg_id = MessageId.deserialize(s)

    **Options**

    * `schema`:
       Define the schema of the data that will be received by this reader.
    * `reader_listener`:
      Sets a message listener for the reader. When the listener is set,
      the application will receive messages through it. Calls to
      `reader.read_next()` will not be allowed. The listener function needs
      to accept (reader, message), for example:

            def my_listener(reader, message):
                # process message
                pass

    * `receiver_queue_size`:
      Sets the size of the reader receive queue. The reader receive
      queue controls how many messages can be accumulated by the reader
      before the application calls `read_next()`. Using a higher value could
      potentially increase the reader throughput at the expense of higher
      memory utilization.
    * `reader_name`:
      Sets the reader name.
    * `subscription_role_prefix`:
      Sets the subscription role prefix.
    """
    _check_type(str, topic, 'topic')
    _check_type(_pulsar.MessageId, start_message_id, 'start_message_id')
    _check_type(_schema.Schema, schema, 'schema')
    _check_type(int, receiver_queue_size, 'receiver_queue_size')
    _check_type_or_none(str, reader_name, 'reader_name')
    _check_type_or_none(str, subscription_role_prefix, 'subscription_role_prefix')

    conf = _pulsar.ReaderConfiguration()
    if reader_listener:
        conf.reader_listener(_listener_wrapper(reader_listener, schema))
    conf.receiver_queue_size(receiver_queue_size)
    if reader_name:
        conf.reader_name(reader_name)
    if subscription_role_prefix:
        conf.subscription_role_prefix(subscription_role_prefix)
    conf.schema(schema.schema_info())

    c = Reader()
    c._reader = self._client.create_reader(topic, start_message_id, conf)
    c._client = self
    c._schema = schema
    self._consumers.append(c)
    return c

def get_topic_partitions(self, topic)

Get the list of partitions for a given topic.

If the topic is partitioned, this will return a list of partition names. If the topic is not partitioned, the returned list will contain the topic name itself.

This can be used to discover the partitions and create Reader, Consumer or Producer instances directly on a particular partition. :param topic: the topic name to lookup :return: a list of partition name

Expand source code

def get_topic_partitions(self, topic):
    """
    Get the list of partitions for a given topic.

    If the topic is partitioned, this will return a list of partition names. If the topic is not
    partitioned, the returned list will contain the topic name itself.

    This can be used to discover the partitions and create Reader, Consumer or Producer
    instances directly on a particular partition.
    :param topic: the topic name to lookup
    :return: a list of partition name
    """
    _check_type(str, topic, 'topic')
    return self._client.get_topic_partitions(topic)

def subscribe(self, topic, subscription_name, consumer_type=_pulsar.ConsumerType.Exclusive, schema=<pulsar.schema.schema.BytesSchema object>, message_listener=None, receiver_queue_size=1000, max_total_receiver_queue_size_across_partitions=50000, consumer_name=None, unacked_messages_timeout_ms=None, broker_consumer_stats_cache_time_ms=30000, is_read_compacted=False, properties=None, pattern_auto_discovery_period=60, initial_position=_pulsar.InitialPosition.Latest)

Subscribe to the given topic and subscription combination.

Args

• topic: The name of the topic, list of topics or regex pattern. This method will accept these forms: - topic='my-topic' - topic=['topic-1', 'topic-2', 'topic-3'] - topic=re.compile('topic-.*')
• subscription: The name of the subscription.

Options

• consumer_type: Select the subscription type to be used when subscribing to the topic.
• pulsar.schema: Define the schema of the data that will be received by this consumer.

• message_listener: Sets a message listener for the consumer. When the listener is set, the application will receive messages through it. Calls to consumer.receive() will not be allowed. The listener function needs to accept (consumer, message), for example:

  #!python
  def my_listener(consumer, message):
      # process message
      consumer.acknowledge(message)
  

• receiver_queue_size: Sets the size of the consumer receive queue. The consumer receive queue controls how many messages can be accumulated by the consumer before the application calls receive(). Using a higher value could potentially increase the consumer throughput at the expense of higher memory utilization. Setting the consumer queue size to zero decreases the throughput of the consumer by disabling pre-fetching of messages. This approach improves the message distribution on shared subscription by pushing messages only to those consumers that are ready to process them. Neither receive with timeout nor partitioned topics can be used if the consumer queue size is zero. The receive() function call should not be interrupted when the consumer queue size is zero. The default value is 1000 messages and should work well for most use cases.

• max_total_receiver_queue_size_across_partitions Set the max total receiver queue size across partitions. This setting will be used to reduce the receiver queue size for individual partitions
• consumer_name: Sets the consumer name.
• unacked_messages_timeout_ms: Sets the timeout in milliseconds for unacknowledged messages. The timeout needs to be greater than 10 seconds. An exception is thrown if the given value is less than 10 seconds. If a successful acknowledgement is not sent within the timeout, all the unacknowledged messages are redelivered.
• broker_consumer_stats_cache_time_ms: Sets the time duration for which the broker-side consumer stats will be cached in the client.
• properties: Sets the properties for the consumer. The properties associated with a consumer can be used for identify a consumer at broker side.
• pattern_auto_discovery_period: Periods of seconds for consumer to auto discover match topics.
• initial_position: Set the initial position of a consumer when subscribing to the topic. It could be either: InitialPosition.Earliest or InitialPosition.Latest. Default: Latest.

Expand source code

def subscribe(self, topic, subscription_name,
              consumer_type=ConsumerType.Exclusive,
              schema=schema.BytesSchema(),
              message_listener=None,
              receiver_queue_size=1000,
              max_total_receiver_queue_size_across_partitions=50000,
              consumer_name=None,
              unacked_messages_timeout_ms=None,
              broker_consumer_stats_cache_time_ms=30000,
              is_read_compacted=False,
              properties=None,
              pattern_auto_discovery_period=60,
              initial_position=InitialPosition.Latest
              ):
    """
    Subscribe to the given topic and subscription combination.

    **Args**

    * `topic`: The name of the topic, list of topics or regex pattern.
              This method will accept these forms:
                - `topic='my-topic'`
                - `topic=['topic-1', 'topic-2', 'topic-3']`
                - `topic=re.compile('topic-.*')`
    * `subscription`: The name of the subscription.

    **Options**

    * `consumer_type`:
      Select the subscription type to be used when subscribing to the topic.
    * `schema`:
       Define the schema of the data that will be received by this consumer.
    * `message_listener`:
      Sets a message listener for the consumer. When the listener is set,
      the application will receive messages through it. Calls to
      `consumer.receive()` will not be allowed. The listener function needs
      to accept (consumer, message), for example:

            #!python
            def my_listener(consumer, message):
                # process message
                consumer.acknowledge(message)

    * `receiver_queue_size`:
      Sets the size of the consumer receive queue. The consumer receive
      queue controls how many messages can be accumulated by the consumer
      before the application calls `receive()`. Using a higher value could
      potentially increase the consumer throughput at the expense of higher
      memory utilization. Setting the consumer queue size to zero decreases
      the throughput of the consumer by disabling pre-fetching of messages.
      This approach improves the message distribution on shared subscription
      by pushing messages only to those consumers that are ready to process
      them. Neither receive with timeout nor partitioned topics can be used
      if the consumer queue size is zero. The `receive()` function call
      should not be interrupted when the consumer queue size is zero. The
      default value is 1000 messages and should work well for most use
      cases.
    * `max_total_receiver_queue_size_across_partitions`
      Set the max total receiver queue size across partitions.
      This setting will be used to reduce the receiver queue size for individual partitions
    * `consumer_name`:
      Sets the consumer name.
    * `unacked_messages_timeout_ms`:
      Sets the timeout in milliseconds for unacknowledged messages. The
      timeout needs to be greater than 10 seconds. An exception is thrown if
      the given value is less than 10 seconds. If a successful
      acknowledgement is not sent within the timeout, all the unacknowledged
      messages are redelivered.
    * `broker_consumer_stats_cache_time_ms`:
      Sets the time duration for which the broker-side consumer stats will
      be cached in the client.
    * `properties`:
      Sets the properties for the consumer. The properties associated with a consumer
      can be used for identify a consumer at broker side.
    * `pattern_auto_discovery_period`:
      Periods of seconds for consumer to auto discover match topics.
    * `initial_position`:
      Set the initial position of a consumer  when subscribing to the topic.
      It could be either: `InitialPosition.Earliest` or `InitialPosition.Latest`.
      Default: `Latest`.
    """
    _check_type(str, subscription_name, 'subscription_name')
    _check_type(ConsumerType, consumer_type, 'consumer_type')
    _check_type(_schema.Schema, schema, 'schema')
    _check_type(int, receiver_queue_size, 'receiver_queue_size')
    _check_type(int, max_total_receiver_queue_size_across_partitions,
                'max_total_receiver_queue_size_across_partitions')
    _check_type_or_none(str, consumer_name, 'consumer_name')
    _check_type_or_none(int, unacked_messages_timeout_ms, 'unacked_messages_timeout_ms')
    _check_type(int, broker_consumer_stats_cache_time_ms, 'broker_consumer_stats_cache_time_ms')
    _check_type(bool, is_read_compacted, 'is_read_compacted')
    _check_type_or_none(dict, properties, 'properties')
    _check_type(InitialPosition, initial_position, 'initial_position')

    conf = _pulsar.ConsumerConfiguration()
    conf.consumer_type(consumer_type)
    conf.read_compacted(is_read_compacted)
    if message_listener:
        conf.message_listener(_listener_wrapper(message_listener, schema))
    conf.receiver_queue_size(receiver_queue_size)
    conf.max_total_receiver_queue_size_across_partitions(max_total_receiver_queue_size_across_partitions)
    if consumer_name:
        conf.consumer_name(consumer_name)
    if unacked_messages_timeout_ms:
        conf.unacked_messages_timeout_ms(unacked_messages_timeout_ms)
    conf.broker_consumer_stats_cache_time_ms(broker_consumer_stats_cache_time_ms)
    if properties:
        for k, v in properties.items():
            conf.property(k, v)
    conf.subscription_initial_position(initial_position)

    conf.schema(schema.schema_info())

    c = Consumer()
    if isinstance(topic, str):
        # Single topic
        c._consumer = self._client.subscribe(topic, subscription_name, conf)
    elif isinstance(topic, list):
        # List of topics
        c._consumer = self._client.subscribe_topics(topic, subscription_name, conf)
    elif isinstance(topic, _retype):
        # Regex pattern
        c._consumer = self._client.subscribe_pattern(topic.pattern, subscription_name, conf)
    else:
        raise ValueError("Argument 'topic' is expected to be of a type between (str, list, re.pattern)")

    c._client = self
    c._schema = schema
    self._consumers.append(c)
    return c

class Consumer (*args, **kwargs)

Pulsar consumer.

Expand source code

class Consumer:
    """
    Pulsar consumer.
    """

    def topic(self):
        """
        Return the topic this consumer is subscribed to.
        """
        return self._consumer.topic()

    def subscription_name(self):
        """
        Return the subscription name.
        """
        return self._consumer.subscription_name()

    def unsubscribe(self):
        """
        Unsubscribe the current consumer from the topic.

        This method will block until the operation is completed. Once the
        consumer is unsubscribed, no more messages will be received and
        subsequent new messages will not be retained for this consumer.

        This consumer object cannot be reused.
        """
        return self._consumer.unsubscribe()

    def receive(self, timeout_millis=None):
        """
        Receive a single message.

        If a message is not immediately available, this method will block until
        a new message is available.

        **Options**

        * `timeout_millis`:
          If specified, the receive will raise an exception if a message is not
          available within the timeout.
        """
        if timeout_millis is None:
            msg = self._consumer.receive()
        else:
            _check_type(int, timeout_millis, 'timeout_millis')
            msg = self._consumer.receive(timeout_millis)

        m = Message()
        m._message = msg
        m._schema = self._schema
        return m

    def acknowledge(self, message):
        """
        Acknowledge the reception of a single message.

        This method will block until an acknowledgement is sent to the broker.
        After that, the message will not be re-delivered to this consumer.

        **Args**

        * `message`:
          The received message or message id.
        """
        if isinstance(message, Message):
            self._consumer.acknowledge(message._message)
        else:
            self._consumer.acknowledge(message)

    def acknowledge_cumulative(self, message):
        """
        Acknowledge the reception of all the messages in the stream up to (and
        including) the provided message.

        This method will block until an acknowledgement is sent to the broker.
        After that, the messages will not be re-delivered to this consumer.

        **Args**

        * `message`:
          The received message or message id.
        """
        if isinstance(message, Message):
            self._consumer.acknowledge_cumulative(message._message)
        else:
            self._consumer.acknowledge_cumulative(message)

    def pause_message_listener(self):
        """
        Pause receiving messages via the `message_listener` until
        `resume_message_listener()` is called.
        """
        self._consumer.pause_message_listener()

    def resume_message_listener(self):
        """
        Resume receiving the messages via the message listener.
        Asynchronously receive all the messages enqueued from the time
        `pause_message_listener()` was called.
        """
        self._consumer.resume_message_listener()

    def redeliver_unacknowledged_messages(self):
        """
        Redelivers all the unacknowledged messages. In failover mode, the
        request is ignored if the consumer is not active for the given topic. In
        shared mode, the consumer's messages to be redelivered are distributed
        across all the connected consumers. This is a non-blocking call and
        doesn't throw an exception. In case the connection breaks, the messages
        are redelivered after reconnect.
        """
        self._consumer.redeliver_unacknowledged_messages()

    def seek(self, messageid):
        """
        Reset the subscription associated with this consumer to a specific message id.
        The message id can either be a specific message or represent the first or last messages in the topic.
        Note: this operation can only be done on non-partitioned topics. For these, one can rather perform the
        seek() on the individual partitions.

        **Args**

        * `message`:
          The message id for seek.
        """
        self._consumer.seek(messageid)

    def close(self):
        """
        Close the consumer.
        """
        self._consumer.close()
        self._client._consumers.remove(self)

Methods

def acknowledge(self, message)

Acknowledge the reception of a single message.

This method will block until an acknowledgement is sent to the broker. After that, the message will not be re-delivered to this consumer.

Args

• message: The received message or message id.

Expand source code

def acknowledge(self, message):
    """
    Acknowledge the reception of a single message.

    This method will block until an acknowledgement is sent to the broker.
    After that, the message will not be re-delivered to this consumer.

    **Args**

    * `message`:
      The received message or message id.
    """
    if isinstance(message, Message):
        self._consumer.acknowledge(message._message)
    else:
        self._consumer.acknowledge(message)

def acknowledge_cumulative(self, message)

Acknowledge the reception of all the messages in the stream up to (and including) the provided message.

This method will block until an acknowledgement is sent to the broker. After that, the messages will not be re-delivered to this consumer.

Args

• message: The received message or message id.

Expand source code

def acknowledge_cumulative(self, message):
    """
    Acknowledge the reception of all the messages in the stream up to (and
    including) the provided message.

    This method will block until an acknowledgement is sent to the broker.
    After that, the messages will not be re-delivered to this consumer.

    **Args**

    * `message`:
      The received message or message id.
    """
    if isinstance(message, Message):
        self._consumer.acknowledge_cumulative(message._message)
    else:
        self._consumer.acknowledge_cumulative(message)

def close(self)

Close the consumer.

Expand source code

def close(self):
    """
    Close the consumer.
    """
    self._consumer.close()
    self._client._consumers.remove(self)

def pause_message_listener(self)

Pause receiving messages via the message_listener until resume_message_listener() is called.

Expand source code

def pause_message_listener(self):
    """
    Pause receiving messages via the `message_listener` until
    `resume_message_listener()` is called.
    """
    self._consumer.pause_message_listener()

def receive(self, timeout_millis=None)

Receive a single message.

If a message is not immediately available, this method will block until a new message is available.

Options

• timeout_millis: If specified, the receive will raise an exception if a message is not available within the timeout.

Expand source code

def receive(self, timeout_millis=None):
    """
    Receive a single message.

    If a message is not immediately available, this method will block until
    a new message is available.

    **Options**

    * `timeout_millis`:
      If specified, the receive will raise an exception if a message is not
      available within the timeout.
    """
    if timeout_millis is None:
        msg = self._consumer.receive()
    else:
        _check_type(int, timeout_millis, 'timeout_millis')
        msg = self._consumer.receive(timeout_millis)

    m = Message()
    m._message = msg
    m._schema = self._schema
    return m

def redeliver_unacknowledged_messages(self)

Redelivers all the unacknowledged messages. In failover mode, the request is ignored if the consumer is not active for the given topic. In shared mode, the consumer's messages to be redelivered are distributed across all the connected consumers. This is a non-blocking call and doesn't throw an exception. In case the connection breaks, the messages are redelivered after reconnect.

Expand source code

def redeliver_unacknowledged_messages(self):
    """
    Redelivers all the unacknowledged messages. In failover mode, the
    request is ignored if the consumer is not active for the given topic. In
    shared mode, the consumer's messages to be redelivered are distributed
    across all the connected consumers. This is a non-blocking call and
    doesn't throw an exception. In case the connection breaks, the messages
    are redelivered after reconnect.
    """
    self._consumer.redeliver_unacknowledged_messages()

def resume_message_listener(self)

Resume receiving the messages via the message listener. Asynchronously receive all the messages enqueued from the time pause_message_listener() was called.

Expand source code

def resume_message_listener(self):
    """
    Resume receiving the messages via the message listener.
    Asynchronously receive all the messages enqueued from the time
    `pause_message_listener()` was called.
    """
    self._consumer.resume_message_listener()

def seek(self, messageid)

Reset the subscription associated with this consumer to a specific message id. The message id can either be a specific message or represent the first or last messages in the topic. Note: this operation can only be done on non-partitioned topics. For these, one can rather perform the seek() on the individual partitions.

Args

• message: The message id for seek.

Expand source code

def seek(self, messageid):
    """
    Reset the subscription associated with this consumer to a specific message id.
    The message id can either be a specific message or represent the first or last messages in the topic.
    Note: this operation can only be done on non-partitioned topics. For these, one can rather perform the
    seek() on the individual partitions.

    **Args**

    * `message`:
      The message id for seek.
    """
    self._consumer.seek(messageid)

def subscription_name(self)

Return the subscription name.

Expand source code

def subscription_name(self):
    """
    Return the subscription name.
    """
    return self._consumer.subscription_name()

def topic(self)

Return the topic this consumer is subscribed to.

Expand source code

def topic(self):
    """
    Return the topic this consumer is subscribed to.
    """
    return self._consumer.topic()

def unsubscribe(self)

Unsubscribe the current consumer from the topic.

This method will block until the operation is completed. Once the consumer is unsubscribed, no more messages will be received and subsequent new messages will not be retained for this consumer.

This consumer object cannot be reused.

Expand source code

def unsubscribe(self):
    """
    Unsubscribe the current consumer from the topic.

    This method will block until the operation is completed. Once the
    consumer is unsubscribed, no more messages will be received and
    subsequent new messages will not be retained for this consumer.

    This consumer object cannot be reused.
    """
    return self._consumer.unsubscribe()

class Message (*args, **kwargs)

Message objects are returned by a consumer, either by calling receive or through a listener.

Expand source code

class Message:
    """
    Message objects are returned by a consumer, either by calling `receive` or
    through a listener.
    """

    def data(self):
        """
        Returns object typed bytes with the payload of the message.
        """
        return self._message.data()

    def value(self):
        """
        Returns object with the de-serialized version of the message content
        """
        return self._schema.decode(self._message.data())

    def properties(self):
        """
        Return the properties attached to the message. Properties are
        application-defined key/value pairs that will be attached to the
        message.
        """
        return self._message.properties()

    def partition_key(self):
        """
        Get the partitioning key for the message.
        """
        return self._message.partition_key()

    def publish_timestamp(self):
        """
        Get the timestamp in milliseconds with the message publish time.
        """
        return self._message.publish_timestamp()

    def event_timestamp(self):
        """
        Get the timestamp in milliseconds with the message event time.
        """
        return self._message.event_timestamp()

    def message_id(self):
        """
        The message ID that can be used to refere to this particular message.
        """
        return self._message.message_id()

    def topic_name(self):
        """
        Get the topic Name from which this message originated from
        """
        return self._message.topic_name()

Methods

def data(self)

Returns object typed bytes with the payload of the message.

Expand source code

def data(self):
    """
    Returns object typed bytes with the payload of the message.
    """
    return self._message.data()

def event_timestamp(self)

Get the timestamp in milliseconds with the message event time.

Expand source code

def event_timestamp(self):
    """
    Get the timestamp in milliseconds with the message event time.
    """
    return self._message.event_timestamp()

def message_id(self)

The message ID that can be used to refere to this particular message.

Expand source code

def message_id(self):
    """
    The message ID that can be used to refere to this particular message.
    """
    return self._message.message_id()

def partition_key(self)

Get the partitioning key for the message.

Expand source code

def partition_key(self):
    """
    Get the partitioning key for the message.
    """
    return self._message.partition_key()

def properties(self)

Return the properties attached to the message. Properties are application-defined key/value pairs that will be attached to the message.

Expand source code

def properties(self):
    """
    Return the properties attached to the message. Properties are
    application-defined key/value pairs that will be attached to the
    message.
    """
    return self._message.properties()

def publish_timestamp(self)

Get the timestamp in milliseconds with the message publish time.

Expand source code

def publish_timestamp(self):
    """
    Get the timestamp in milliseconds with the message publish time.
    """
    return self._message.publish_timestamp()

def topic_name(self)

Get the topic Name from which this message originated from

Expand source code

def topic_name(self):
    """
    Get the topic Name from which this message originated from
    """
    return self._message.topic_name()

def value(self)

Returns object with the de-serialized version of the message content

Expand source code

def value(self):
    """
    Returns object with the de-serialized version of the message content
    """
    return self._schema.decode(self._message.data())

class MessageId (*args, **kwargs)

Represents a message id

Expand source code

class MessageId:
    """
    Represents a message id
    """

    'Represents the earliest message stored in a topic'
    earliest = _pulsar.MessageId.earliest

    'Represents the latest message published on a topic'
    latest = _pulsar.MessageId.latest

    def serialize(self):
        """
        Returns a bytes representation of the message id.
        This bytes sequence can be stored and later deserialized.
        """
        return self._msg_id.serialize()

    @staticmethod
    def deserialize(message_id_bytes):
        """
        Deserialize a message id object from a previously
        serialized bytes sequence.
        """
        return _pulsar.MessageId.deserialize(message_id_bytes)

Class variables

var earliest

Represents the latest message published on a topic

var latest

Static methods

def deserialize(message_id_bytes)

Deserialize a message id object from a previously serialized bytes sequence.

Expand source code

@staticmethod
def deserialize(message_id_bytes):
    """
    Deserialize a message id object from a previously
    serialized bytes sequence.
    """
    return _pulsar.MessageId.deserialize(message_id_bytes)

Methods

def serialize(self)

Returns a bytes representation of the message id. This bytes sequence can be stored and later deserialized.

Expand source code

def serialize(self):
    """
    Returns a bytes representation of the message id.
    This bytes sequence can be stored and later deserialized.
    """
    return self._msg_id.serialize()

class Producer (*args, **kwargs)

The Pulsar message producer, used to publish messages on a topic.

Expand source code

class Producer:
    """
    The Pulsar message producer, used to publish messages on a topic.
    """

    def topic(self):
        """
        Return the topic which producer is publishing to
        """
        return self._producer.topic()

    def producer_name(self):
        """
        Return the producer name which could have been assigned by the
        system or specified by the client
        """
        return self._producer.producer_name()

    def last_sequence_id(self):
        """
        Get the last sequence id that was published by this producer.

        This represent either the automatically assigned or custom sequence id
        (set on the `MessageBuilder`) that was published and acknowledged by the broker.

        After recreating a producer with the same producer name, this will return the
        last message that was published in the previous producer session, or -1 if
        there no message was ever published.
        """
        return self._producer.last_sequence_id()

    def send(self, content,
             properties=None,
             partition_key=None,
             sequence_id=None,
             replication_clusters=None,
             disable_replication=False,
             event_timestamp=None,
             ):
        """
        Publish a message on the topic. Blocks until the message is acknowledged

        **Args**

        * `content`:
          A `bytes` object with the message payload.

        **Options**

        * `properties`:
          A dict of application-defined string properties.
        * `partition_key`:
          Sets the partition key for message routing. A hash of this key is used
          to determine the message's topic partition.
        * `sequence_id`:
          Specify a custom sequence id for the message being published.
        * `replication_clusters`:
          Override namespace replication clusters. Note that it is the caller's
          responsibility to provide valid cluster names and that all clusters
          have been previously configured as topics. Given an empty list,
          the message will replicate according to the namespace configuration.
        * `disable_replication`:
          Do not replicate this message.
        * `event_timestamp`:
          Timestamp in millis of the timestamp of event creation
        """
        msg = self._build_msg(content, properties, partition_key, sequence_id,
                              replication_clusters, disable_replication, event_timestamp)
        return self._producer.send(msg)

    def send_async(self, content, callback,
                   properties=None,
                   partition_key=None,
                   sequence_id=None,
                   replication_clusters=None,
                   disable_replication=False,
                   event_timestamp=None
                   ):
        """
        Send a message asynchronously.

        The `callback` will be invoked once the message has been acknowledged
        by the broker.

        Example:

            #!python
            def callback(res, msg):
                print('Message published: %s' % res)

            producer.send_async(msg, callback)

        When the producer queue is full, by default the message will be rejected
        and the callback invoked with an error code.

        **Args**

        * `content`:
          A `bytes` object with the message payload.

        **Options**

        * `properties`:
          A dict of application0-defined string properties.
        * `partition_key`:
          Sets the partition key for the message routing. A hash of this key is
          used to determine the message's topic partition.
        * `sequence_id`:
          Specify a custom sequence id for the message being published.
        * `replication_clusters`: Override namespace replication clusters. Note
          that it is the caller's responsibility to provide valid cluster names
          and that all clusters have been previously configured as topics.
          Given an empty list, the message will replicate per the namespace
          configuration.
        * `disable_replication`:
          Do not replicate this message.
        * `event_timestamp`:
          Timestamp in millis of the timestamp of event creation
        """
        msg = self._build_msg(content, properties, partition_key, sequence_id,
                              replication_clusters, disable_replication, event_timestamp)
        self._producer.send_async(msg, callback)


    def flush(self):
        """
        Flush all the messages buffered in the client and wait until all messages have been
        successfully persisted
        """
        self._producer.flush()
        

    def close(self):
        """
        Close the producer.
        """
        self._producer.close()

    def _build_msg(self, content, properties, partition_key, sequence_id,
                   replication_clusters, disable_replication, event_timestamp):
        data = self._schema.encode(content)

        _check_type(bytes, data, 'data')
        _check_type_or_none(dict, properties, 'properties')
        _check_type_or_none(str, partition_key, 'partition_key')
        _check_type_or_none(int, sequence_id, 'sequence_id')
        _check_type_or_none(list, replication_clusters, 'replication_clusters')
        _check_type(bool, disable_replication, 'disable_replication')
        _check_type_or_none(int, event_timestamp, 'event_timestamp')

        mb = _pulsar.MessageBuilder()
        mb.content(data)
        if properties:
            for k, v in properties.items():
                mb.property(k, v)
        if partition_key:
            mb.partition_key(partition_key)
        if sequence_id:
            mb.sequence_id(sequence_id)
        if replication_clusters:
            mb.replication_clusters(replication_clusters)
        if disable_replication:
            mb.disable_replication(disable_replication)
        if event_timestamp:
            mb.event_timestamp(event_timestamp)
        return mb.build()

Methods

def close(self)

Close the producer.

Expand source code

def close(self):
    """
    Close the producer.
    """
    self._producer.close()

def flush(self)

Flush all the messages buffered in the client and wait until all messages have been successfully persisted

Expand source code

def flush(self):
    """
    Flush all the messages buffered in the client and wait until all messages have been
    successfully persisted
    """
    self._producer.flush()

def last_sequence_id(self)

Get the last sequence id that was published by this producer.

This represent either the automatically assigned or custom sequence id (set on the MessageBuilder) that was published and acknowledged by the broker.

After recreating a producer with the same producer name, this will return the last message that was published in the previous producer session, or -1 if there no message was ever published.

Expand source code

def last_sequence_id(self):
    """
    Get the last sequence id that was published by this producer.

    This represent either the automatically assigned or custom sequence id
    (set on the `MessageBuilder`) that was published and acknowledged by the broker.

    After recreating a producer with the same producer name, this will return the
    last message that was published in the previous producer session, or -1 if
    there no message was ever published.
    """
    return self._producer.last_sequence_id()

def producer_name(self)

Return the producer name which could have been assigned by the system or specified by the client

Expand source code

def producer_name(self):
    """
    Return the producer name which could have been assigned by the
    system or specified by the client
    """
    return self._producer.producer_name()

def send(self, content, properties=None, partition_key=None, sequence_id=None, replication_clusters=None, disable_replication=False, event_timestamp=None)

Publish a message on the topic. Blocks until the message is acknowledged

Args

• content: A bytes object with the message payload.

Options

• properties: A dict of application-defined string properties.
• partition_key: Sets the partition key for message routing. A hash of this key is used to determine the message's topic partition.
• sequence_id: Specify a custom sequence id for the message being published.
• replication_clusters: Override namespace replication clusters. Note that it is the caller's responsibility to provide valid cluster names and that all clusters have been previously configured as topics. Given an empty list, the message will replicate according to the namespace configuration.
• disable_replication: Do not replicate this message.
• event_timestamp: Timestamp in millis of the timestamp of event creation

Expand source code

def send(self, content,
         properties=None,
         partition_key=None,
         sequence_id=None,
         replication_clusters=None,
         disable_replication=False,
         event_timestamp=None,
         ):
    """
    Publish a message on the topic. Blocks until the message is acknowledged

    **Args**

    * `content`:
      A `bytes` object with the message payload.

    **Options**

    * `properties`:
      A dict of application-defined string properties.
    * `partition_key`:
      Sets the partition key for message routing. A hash of this key is used
      to determine the message's topic partition.
    * `sequence_id`:
      Specify a custom sequence id for the message being published.
    * `replication_clusters`:
      Override namespace replication clusters. Note that it is the caller's
      responsibility to provide valid cluster names and that all clusters
      have been previously configured as topics. Given an empty list,
      the message will replicate according to the namespace configuration.
    * `disable_replication`:
      Do not replicate this message.
    * `event_timestamp`:
      Timestamp in millis of the timestamp of event creation
    """
    msg = self._build_msg(content, properties, partition_key, sequence_id,
                          replication_clusters, disable_replication, event_timestamp)
    return self._producer.send(msg)

def send_async(self, content, callback, properties=None, partition_key=None, sequence_id=None, replication_clusters=None, disable_replication=False, event_timestamp=None)

Send a message asynchronously.

The callback will be invoked once the message has been acknowledged by the broker.

Example

!python

def callback(res, msg): print('Message published: %s' % res)

producer.send_async(msg, callback) When the producer queue is full, by default the message will be rejected and the callback invoked with an error code.

Args

• content: A bytes object with the message payload.

Options

• properties: A dict of application0-defined string properties.
• partition_key: Sets the partition key for the message routing. A hash of this key is used to determine the message's topic partition.
• sequence_id: Specify a custom sequence id for the message being published.
• replication_clusters: Override namespace replication clusters. Note that it is the caller's responsibility to provide valid cluster names and that all clusters have been previously configured as topics. Given an empty list, the message will replicate per the namespace configuration.
• disable_replication: Do not replicate this message.
• event_timestamp: Timestamp in millis of the timestamp of event creation

Expand source code

def send_async(self, content, callback,
               properties=None,
               partition_key=None,
               sequence_id=None,
               replication_clusters=None,
               disable_replication=False,
               event_timestamp=None
               ):
    """
    Send a message asynchronously.

    The `callback` will be invoked once the message has been acknowledged
    by the broker.

    Example:

        #!python
        def callback(res, msg):
            print('Message published: %s' % res)

        producer.send_async(msg, callback)

    When the producer queue is full, by default the message will be rejected
    and the callback invoked with an error code.

    **Args**

    * `content`:
      A `bytes` object with the message payload.

    **Options**

    * `properties`:
      A dict of application0-defined string properties.
    * `partition_key`:
      Sets the partition key for the message routing. A hash of this key is
      used to determine the message's topic partition.
    * `sequence_id`:
      Specify a custom sequence id for the message being published.
    * `replication_clusters`: Override namespace replication clusters. Note
      that it is the caller's responsibility to provide valid cluster names
      and that all clusters have been previously configured as topics.
      Given an empty list, the message will replicate per the namespace
      configuration.
    * `disable_replication`:
      Do not replicate this message.
    * `event_timestamp`:
      Timestamp in millis of the timestamp of event creation
    """
    msg = self._build_msg(content, properties, partition_key, sequence_id,
                          replication_clusters, disable_replication, event_timestamp)
    self._producer.send_async(msg, callback)

def topic(self)

Return the topic which producer is publishing to

Expand source code

def topic(self):
    """
    Return the topic which producer is publishing to
    """
    return self._producer.topic()

class Reader (*args, **kwargs)

Pulsar topic reader.

Expand source code

class Reader:
    """
    Pulsar topic reader.
    """

    def topic(self):
        """
        Return the topic this reader is reading from.
        """
        return self._reader.topic()

    def read_next(self, timeout_millis=None):
        """
        Read a single message.

        If a message is not immediately available, this method will block until
        a new message is available.

        **Options**

        * `timeout_millis`:
          If specified, the receive will raise an exception if a message is not
          available within the timeout.
        """
        if timeout_millis is None:
            msg = self._reader.read_next()
        else:
            _check_type(int, timeout_millis, 'timeout_millis')
            msg = self._reader.read_next(timeout_millis)

        m = Message()
        m._message = msg
        m._schema = self._schema
        return m

    def has_message_available(self):
        """
        Check if there is any message available to read from the current position.
        """
        return self._reader.has_message_available();

    def close(self):
        """
        Close the reader.
        """
        self._reader.close()
        self._client._consumers.remove(self)

Methods

def close(self)

Close the reader.

Expand source code

def close(self):
    """
    Close the reader.
    """
    self._reader.close()
    self._client._consumers.remove(self)

def has_message_available(self)

Check if there is any message available to read from the current position.

Expand source code

def has_message_available(self):
    """
    Check if there is any message available to read from the current position.
    """
    return self._reader.has_message_available();

def read_next(self, timeout_millis=None)

Read a single message.

If a message is not immediately available, this method will block until a new message is available.

Options

• timeout_millis: If specified, the receive will raise an exception if a message is not available within the timeout.

Expand source code

def read_next(self, timeout_millis=None):
    """
    Read a single message.

    If a message is not immediately available, this method will block until
    a new message is available.

    **Options**

    * `timeout_millis`:
      If specified, the receive will raise an exception if a message is not
      available within the timeout.
    """
    if timeout_millis is None:
        msg = self._reader.read_next()
    else:
        _check_type(int, timeout_millis, 'timeout_millis')
        msg = self._reader.read_next(timeout_millis)

    m = Message()
    m._message = msg
    m._schema = self._schema
    return m

def topic(self)

Return the topic this reader is reading from.

Expand source code

def topic(self):
    """
    Return the topic this reader is reading from.
    """
    return self._reader.topic()