EventHubConsumerClient Class
The EventHubConsumerClient class defines a high level interface for receiving events from the Azure Event Hubs service.
The main goal of EventHubConsumerClient is to receive events from all partitions of an EventHub with load-balancing and checkpointing.
When multiple EventHubConsumerClient instances are running against the same event hub, consumer group and checkpointing location, the partitions will be evenly distributed among them.
To enable load-balancing and persisted checkpoints, checkpoint_store must be set when creating the EventHubConsumerClient. If a checkpoint store is not provided, the checkpoint will be maintained internally in memory.
An EventHubConsumerClient can also receive from a specific partition when you call its method receive() or receive_batch() and specify the partition_id. Load-balancing won't work in single-partition mode. But users can still save checkpoints if the checkpoint_store is set.
- Inheritance
-
azure.eventhub.aio._client_base_async.ClientBaseAsyncEventHubConsumerClient
Constructor
EventHubConsumerClient(fully_qualified_namespace: str, eventhub_name: str, consumer_group: str, credential: CredentialTypes, **kwargs: Any)
Parameters
Name | Description |
---|---|
fully_qualified_namespace
Required
|
The fully qualified host name for the Event Hubs namespace. The namespace format is: .servicebus.windows.net. |
eventhub_name
Required
|
The path of the specific Event Hub to connect the client to. |
consumer_group
Required
|
Receive events from the event hub for this consumer group. |
credential
Required
|
The credential object used for authentication which implements a particular interface for getting tokens. It accepts EventHubSharedKeyCredential, or credential objects generated by the azure-identity library and objects that implement the *get_token(self, scopes) method. |
Keyword-Only Parameters
Name | Description |
---|---|
logging_enable
|
Whether to output network trace logs to the logger. Default is False. |
auth_timeout
|
The time in seconds to wait for a token to be authorized by the service. The default value is 60 seconds. If set to 0, no timeout will be enforced from the client. |
user_agent
|
If specified, this will be added in front of the user agent string. |
retry_total
|
The total number of attempts to redo a failed operation when an error occurs. Default value is 3. The context of retry_total in receiving is special: The receive method is implemented by a while-loop calling internal receive method in each iteration. In the receive case, retry_total specifies the numbers of retry after error raised by internal receive method in the while-loop. If retry attempts are exhausted, the on_error callback will be called (if provided) with the error information. The failed internal partition consumer will be closed (on_partition_close will be called if provided) and new internal partition consumer will be created (on_partition_initialize will be called if provided) to resume receiving. |
retry_backoff_factor
|
A backoff factor to apply between attempts after the second try (most errors are resolved immediately by a second try without a delay). In fixed mode, retry policy will always sleep for {backoff factor}. In 'exponential' mode, retry policy will sleep for: {backoff factor} * (2 ** ({number of total retries} - 1)) seconds. If the backoff_factor is 0.1, then the retry will sleep for [0.0s, 0.2s, 0.4s, ...] between retries. The default value is 0.8. |
retry_backoff_max
|
The maximum back off time. Default value is 120 seconds (2 minutes). |
retry_mode
|
The delay behavior between retry attempts. Supported values are 'fixed' or 'exponential', where default is 'exponential'. |
idle_timeout
|
Timeout, in seconds, after which this client will close the underlying connection if there is no further activity. By default the value is None, meaning that the client will not shutdown due to inactivity unless initiated by the service. |
transport_type
|
The type of transport protocol that will be used for communicating with the Event Hubs service. Default is TransportType.Amqp in which case port 5671 is used. If the port 5671 is unavailable/blocked in the network environment, TransportType.AmqpOverWebsocket could be used instead which uses port 443 for communication. |
http_proxy
|
HTTP proxy settings. This must be a dictionary with the following keys: 'proxy_hostname' (str value) and 'proxy_port' (int value). |
checkpoint_store
|
A manager that stores the partition load-balancing and checkpoint data when receiving events. The checkpoint store will be used in both cases of receiving from all partitions or a single partition. In the latter case load-balancing does not apply. If a checkpoint store is not provided, the checkpoint will be maintained internally in memory, and the EventHubConsumerClient instance will receive events without load-balancing. |
load_balancing_interval
|
When load-balancing kicks in. This is the interval, in seconds, between two load-balancing evaluations. Default is 30 seconds. |
partition_ownership_expiration_interval
|
A partition ownership will expire after this number of seconds. Every load-balancing evaluation will automatically extend the ownership expiration time. Default is 6 * load_balancing_interval, i.e. 180 seconds when using the default load_balancing_interval of 30 seconds. |
load_balancing_strategy
|
When load-balancing kicks in, it will use this strategy to claim and balance the partition ownership. Use "greedy" or LoadBalancingStrategy.GREEDY for the greedy strategy, which, for every load-balancing evaluation, will grab as many unclaimed partitions required to balance the load. Use "balanced" or LoadBalancingStrategy.BALANCED for the balanced strategy, which, for every load-balancing evaluation, claims only one partition that is not claimed by other EventHubConsumerClient. If all partitions of an EventHub are claimed by other EventHubConsumerClient and this client has claimed too few partitions, this client will steal one partition from other clients for every load-balancing evaluation regardless of the load balancing strategy. Greedy strategy is used by default. |
custom_endpoint_address
|
The custom endpoint address to use for establishing a connection to the Event Hubs service, allowing network requests to be routed through any application gateways or other paths needed for the host environment. Default is None. The format would be like "sb://<custom_endpoint_hostname>:<custom_endpoint_port>". If port is not specified in the custom_endpoint_address, by default port 443 will be used. |
connection_verify
|
Path to the custom CA_BUNDLE file of the SSL certificate which is used to authenticate the identity of the connection endpoint. Default is None in which case certifi.where() will be used. |
uamqp_transport
|
Whether to use the uamqp library as the underlying transport. The default value is False and the Pure Python AMQP library will be used as the underlying transport. |
socket_timeout
|
The time in seconds that the underlying socket on the connection should wait when sending and receiving data before timing out. The default value is 0.2 for TransportType.Amqp and 1 for TransportType.AmqpOverWebsocket. If EventHubsConnectionError errors are occurring due to write timing out, a larger than default value may need to be passed in. This is for advanced usage scenarios and ordinarily the default value should be sufficient. |
Examples
Create a new instance of the EventHubConsumerClient.
import os
from azure.eventhub.aio import EventHubConsumerClient, EventHubSharedKeyCredential
fully_qualified_namespace = os.environ['EVENT_HUB_HOSTNAME']
eventhub_name = os.environ['EVENT_HUB_NAME']
shared_access_policy = os.environ['EVENT_HUB_SAS_POLICY']
shared_access_key = os.environ['EVENT_HUB_SAS_KEY']
consumer = EventHubConsumerClient(fully_qualified_namespace=fully_qualified_namespace,
consumer_group='$Default',
eventhub_name=eventhub_name,
credential=EventHubSharedKeyCredential(shared_access_policy, shared_access_key))
Methods
close |
Stop retrieving events from the Event Hub and close the underlying AMQP connection and links. |
from_connection_string |
Create an EventHubConsumerClient from a connection string. |
get_eventhub_properties |
Get properties of the Event Hub. Keys in the returned dictionary include:
|
get_partition_ids |
Get partition IDs of the Event Hub. |
get_partition_properties |
Get properties of the specified partition. Keys in the properties dictionary include:
|
receive |
Receive events from partition(s), with optional load-balancing and checkpointing. |
receive_batch |
Receive events from partition(s) in batches, with optional load-balancing and checkpointing. |
close
Stop retrieving events from the Event Hub and close the underlying AMQP connection and links.
async close() -> None
Returns
Type | Description |
---|---|
Examples
Close down the client.
import os
from azure.identity.aio import DefaultAzureCredential
fully_qualified_namespace = os.environ["EVENT_HUB_HOSTNAME"]
eventhub_name = os.environ['EVENT_HUB_NAME']
from azure.eventhub.aio import EventHubConsumerClient
consumer = EventHubConsumerClient(
fully_qualified_namespace=fully_qualified_namespace,
consumer_group='$Default',
eventhub_name=eventhub_name, # EventHub name should be specified if it doesn't show up in connection string.
credential=DefaultAzureCredential()
)
logger = logging.getLogger("azure.eventhub")
async def on_event(partition_context, event):
# Put your code here.
# If the operation is i/o intensive, async will have better performance.
logger.info("Received event from partition: {}".format(partition_context.partition_id))
# The receive method is a coroutine which will be blocking when awaited.
# It can be executed in an async task for non-blocking behavior, and combined with the 'close' method.
recv_task = asyncio.ensure_future(consumer.receive(on_event=on_event))
await asyncio.sleep(3) # keep receiving for 3 seconds
recv_task.cancel() # stop receiving
# Close down the consumer handler explicitly.
await consumer.close()
from_connection_string
Create an EventHubConsumerClient from a connection string.
from_connection_string(conn_str: str, consumer_group: str, *, eventhub_name: str | None = None, logging_enable: bool = False, http_proxy: Dict[str, str | int] | None = None, auth_timeout: float = 60, user_agent: str | None = None, retry_total: int = 3, retry_backoff_factor: float = 0.8, retry_backoff_max: float = 120, retry_mode: Literal['exponential', 'fixed'] = 'exponential', idle_timeout: float | None = None, transport_type: TransportType = TransportType.Amqp, checkpoint_store: 'CheckpointStore' | None = None, load_balancing_interval: float = 30, partition_ownership_expiration_interval: float | None = None, load_balancing_strategy: str | LoadBalancingStrategy = LoadBalancingStrategy.GREEDY, custom_endpoint_address: str | None = None, connection_verify: str | None = None, uamqp_transport: bool = False, **kwargs: Any) -> EventHubConsumerClient
Parameters
Name | Description |
---|---|
conn_str
Required
|
The connection string of an Event Hub. |
consumer_group
Required
|
Receive events from the Event Hub for this consumer group. |
Keyword-Only Parameters
Name | Description |
---|---|
eventhub_name
|
The path of the specific Event Hub to connect the client to. |
logging_enable
|
Whether to output network trace logs to the logger. Default is False. |
http_proxy
|
HTTP proxy settings. This must be a dictionary with the following keys: 'proxy_hostname' (str value) and 'proxy_port' (int value). Additionally the following keys may also be present: 'username', 'password'. |
auth_timeout
|
The time in seconds to wait for a token to be authorized by the service. The default value is 60 seconds. If set to 0, no timeout will be enforced from the client. Default value: 60
|
user_agent
|
If specified, this will be added in front of the user agent string. |
retry_total
|
The total number of attempts to redo a failed operation when an error occurs. Default value is 3. The context of retry_total in receiving is special: The receive method is implemented by a while-loop calling internal receive method in each iteration. In the receive case, retry_total specifies the numbers of retry after error raised by internal receive method in the while-loop. If retry attempts are exhausted, the on_error callback will be called (if provided) with the error information. The failed internal partition consumer will be closed (on_partition_close will be called if provided) and new internal partition consumer will be created (on_partition_initialize will be called if provided) to resume receiving. Default value: 3
|
retry_backoff_factor
|
A backoff factor to apply between attempts after the second try (most errors are resolved immediately by a second try without a delay). In fixed mode, retry policy will always sleep for {backoff factor}. In 'exponential' mode, retry policy will sleep for: {backoff factor} * (2 ** ({number of total retries} - 1)) seconds. If the backoff_factor is 0.1, then the retry will sleep for [0.0s, 0.2s, 0.4s, ...] between retries. The default value is 0.8. Default value: 0.8
|
retry_backoff_max
|
The maximum back off time. Default value is 120 seconds (2 minutes). Default value: 120
|
retry_mode
|
The delay behavior between retry attempts. Supported values are 'fixed' or 'exponential', where default is 'exponential'. Default value: exponential
|
idle_timeout
|
Timeout, in seconds, after which this client will close the underlying connection if there is no further activity. By default the value is None, meaning that the client will not shutdown due to inactivity unless initiated by the service. |
transport_type
|
The type of transport protocol that will be used for communicating with the Event Hubs service. Default is TransportType.Amqp in which case port 5671 is used. If the port 5671 is unavailable/blocked in the network environment, TransportType.AmqpOverWebsocket could be used instead which uses port 443 for communication. Default value: TransportType.Amqp
|
checkpoint_store
|
A manager that stores the partition load-balancing and checkpoint data when receiving events. The checkpoint store will be used in both cases of receiving from all partitions or a single partition. In the latter case load-balancing does not apply. If a checkpoint store is not provided, the checkpoint will be maintained internally in memory, and the EventHubConsumerClient instance will receive events without load-balancing. |
load_balancing_interval
|
When load-balancing kicks in. This is the interval, in seconds, between two load-balancing evaluations. Default is 30 seconds. Default value: 30
|
partition_ownership_expiration_interval
|
A partition ownership will expire after this number of seconds. Every load-balancing evaluation will automatically extend the ownership expiration time. Default is 6 * load_balancing_interval, i.e. 180 seconds when using the default load_balancing_interval of 30 seconds. |
load_balancing_strategy
|
When load-balancing kicks in, it will use this strategy to claim and balance the partition ownership. Use "greedy" or LoadBalancingStrategy.GREEDY for the greedy strategy, which, for every load-balancing evaluation, will grab as many unclaimed partitions required to balance the load. Use "balanced" or LoadBalancingStrategy.BALANCED for the balanced strategy, which, for every load-balancing evaluation, claims only one partition that is not claimed by other EventHubConsumerClient. If all partitions of an EventHub are claimed by other EventHubConsumerClient and this client has claimed too few partitions, this client will steal one partition from other clients for every load-balancing evaluation regardless of the load balancing strategy. Greedy strategy is used by default. Default value: LoadBalancingStrategy.GREEDY
|
custom_endpoint_address
|
The custom endpoint address to use for establishing a connection to the Event Hubs service, allowing network requests to be routed through any application gateways or other paths needed for the host environment. Default is None. The format would be like "sb://<custom_endpoint_hostname>:<custom_endpoint_port>". If port is not specified in the custom_endpoint_address, by default port 443 will be used. |
connection_verify
|
Path to the custom CA_BUNDLE file of the SSL certificate which is used to authenticate the identity of the connection endpoint. Default is None in which case certifi.where() will be used. |
uamqp_transport
|
Whether to use the uamqp library as the underlying transport. The default value is False and the Pure Python AMQP library will be used as the underlying transport. |
Returns
Type | Description |
---|---|
An EventHubConsumerClient instance. |
Examples
Create a new instance of the EventHubConsumerClient from connection string.
import os
from azure.eventhub.aio import EventHubConsumerClient
from azure.identity.aio import DefaultAzureCredential
fully_qualified_namespace = os.environ["EVENT_HUB_HOSTNAME"]
eventhub_name = os.environ['EVENT_HUB_NAME']
consumer = EventHubConsumerClient(
fully_qualified_namespace=fully_qualified_namespace,
credential=DefaultAzureCredential(),
consumer_group='$Default',
eventhub_name=eventhub_name # EventHub name should be specified if it doesn't show up in connection string.
)
get_eventhub_properties
Get properties of the Event Hub.
Keys in the returned dictionary include:
eventhub_name (str)
created_at (UTC datetime.datetime)
partition_ids (list[str])
async get_eventhub_properties() -> Dict[str, Any]
Returns
Type | Description |
---|---|
A dictionary containing information about the Event Hub. |
Exceptions
Type | Description |
---|---|
get_partition_ids
Get partition IDs of the Event Hub.
async get_partition_ids() -> List[str]
Returns
Type | Description |
---|---|
A list of partition IDs. |
Exceptions
Type | Description |
---|---|
get_partition_properties
Get properties of the specified partition.
Keys in the properties dictionary include:
eventhub_name (str)
id (str)
beginning_sequence_number (int)
last_enqueued_sequence_number (int)
last_enqueued_offset (str)
last_enqueued_time_utc (UTC datetime.datetime)
is_empty (bool)
async get_partition_properties(partition_id: str) -> Dict[str, Any]
Parameters
Name | Description |
---|---|
partition_id
Required
|
The target partition ID. |
Returns
Type | Description |
---|---|
A dictionary containing partition properties. |
Exceptions
Type | Description |
---|---|
receive
Receive events from partition(s), with optional load-balancing and checkpointing.
async receive(on_event: Callable[['PartitionContext', 'EventData' | None], Awaitable[None]], *, max_wait_time: float | None = None, partition_id: str | None = None, owner_level: int | None = None, prefetch: int = 300, track_last_enqueued_event_properties: bool = False, starting_position: str | int | datetime.datetime | Dict[str, Any] | None = None, starting_position_inclusive: bool | Dict[str, bool] = False, on_error: Callable[['PartitionContext', Exception], Awaitable[None]] | None = None, on_partition_initialize: Callable[['PartitionContext'], Awaitable[None]] | None = None, on_partition_close: Callable[['PartitionContext', 'CloseReason'], Awaitable[None]] | None = None) -> None
Parameters
Name | Description |
---|---|
on_event
Required
|
The callback function for handling a received event. The callback takes two parameters: partition_context which contains partition context and event which is the received event. The callback function should be defined like: on_event(partition_context, event). For detailed partition context information, please refer to PartitionContext. |
Keyword-Only Parameters
Name | Description |
---|---|
max_wait_time
|
The maximum interval in seconds that the event processor will wait before calling the callback. If no events are received within this interval, the on_event callback will be called with None. If this value is set to None or 0 (the default), the callback will not be called until an event is received. |
partition_id
|
If specified, the client will receive from this partition only. Otherwise the client will receive from all partitions. |
owner_level
|
The priority for an exclusive consumer. An exclusive consumer will be created if owner_level is set. A consumer with a higher owner_level has higher exclusive priority. The owner level is also know as the 'epoch value' of the consumer. |
prefetch
|
The number of events to prefetch from the service for processing. Default is 300. Default value: 300
|
track_last_enqueued_event_properties
|
Indicates whether the consumer should request information on the last-enqueued event on its associated partition, and track that information as events are received. When information about the partitions last-enqueued event is being tracked, each event received from the Event Hubs service will carry metadata about the partition. This results in a small amount of additional network bandwidth consumption that is generally a favorable trade-off when considered against periodically making requests for partition properties using the Event Hub client. It is set to False by default. |
starting_position
|
Start receiving from this event position if there is no checkpoint data for a partition. Checkpoint data will be used if available. This can be a a dict with partition ID as the key and position as the value for individual partitions, or a single value for all partitions. The value type can be str, int or datetime.datetime. Also supported are the values "-1" for receiving from the beginning of the stream, and "@latest" for receiving only new events. |
starting_position_inclusive
|
Determine whether the given starting_position is inclusive(>=) or not (>). True for inclusive and False for exclusive. This can be a dict with partition ID as the key and bool as the value indicating whether the starting_position for a specific partition is inclusive or not. This can also be a single bool value for all starting_position. The default value is False. |
on_error
|
The callback function that will be called when an error is raised during receiving after retry attempts are exhausted, or during the process of load-balancing. The callback takes two parameters: partition_context which contains partition information and error being the exception. partition_context could be None if the error is raised during the process of load-balance. The callback should be defined like: on_error(partition_context, error). The on_error callback will also be called if an unhandled exception is raised during the on_event callback. |
on_partition_initialize
|
The callback function that will be called after a consumer for a certain partition finishes initialization. It would also be called when a new internal partition consumer is created to take over the receiving process for a failed and closed internal partition consumer. The callback takes a single parameter: partition_context which contains the partition information. The callback should be defined like: on_partition_initialize(partition_context). |
on_partition_close
|
The callback function that will be called after a consumer for a certain partition is closed. It would be also called when error is raised during receiving after retry attempts are exhausted. The callback takes two parameters: partition_context which contains partition information and reason for the close. The callback should be defined like: on_partition_close(partition_context, reason). Please refer to CloseReason for the various closing reasons. |
Returns
Type | Description |
---|---|
Examples
Receive events from the EventHub.
logger = logging.getLogger("azure.eventhub")
async def on_event(partition_context, event):
# Put your code here.
# If the operation is i/o intensive, async will have better performance.
logger.info("Received event from partition: {}".format(partition_context.partition_id))
async with consumer:
await consumer.receive(
on_event=on_event,
starting_position="-1", # "-1" is from the beginning of the partition.
)
receive_batch
Receive events from partition(s) in batches, with optional load-balancing and checkpointing.
async receive_batch(on_event_batch: Callable[['PartitionContext', List['EventData']], Awaitable[None]], *, max_batch_size: int = 300, max_wait_time: float | None = None, partition_id: str | None = None, owner_level: int | None = None, prefetch: int = 300, track_last_enqueued_event_properties: bool = False, starting_position: str | int | datetime.datetime | Dict[str, Any] | None = None, starting_position_inclusive: bool | Dict[str, bool] = False, on_error: Callable[['PartitionContext', Exception], Awaitable[None]] | None = None, on_partition_initialize: Callable[['PartitionContext'], Awaitable[None]] | None = None, on_partition_close: Callable[['PartitionContext', 'CloseReason'], Awaitable[None]] | None = None) -> None
Parameters
Name | Description |
---|---|
on_event_batch
Required
|
The callback function for handling a batch of received events. The callback takes two parameters: partition_context which contains partition context and event_batch, which is the received events. The callback function should be defined like: on_event_batch(partition_context, event_batch). event_batch could be an empty list if max_wait_time is not None nor 0 and no event is received after max_wait_time. For detailed partition context information, please refer to PartitionContext. |
Keyword-Only Parameters
Name | Description |
---|---|
max_batch_size
|
The maximum number of events in a batch passed to callback on_event_batch. If the actual received number of events is larger than max_batch_size, the received events are divided into batches and call the callback for each batch with up to max_batch_size events. Default value: 300
|
max_wait_time
|
The maximum interval in seconds that the event processor will wait before calling the callback. If no events are received within this interval, the on_event_batch callback will be called with an empty list. If this value is set to None or 0 (the default), the callback will not be called until events are received. |
partition_id
|
If specified, the client will receive from this partition only. Otherwise the client will receive from all partitions. |
owner_level
|
The priority for an exclusive consumer. An exclusive consumer will be created if owner_level is set. A consumer with a higher owner_level has higher exclusive priority. The owner level is also know as the 'epoch value' of the consumer. |
prefetch
|
The number of events to prefetch from the service for processing. Default is 300. Default value: 300
|
track_last_enqueued_event_properties
|
Indicates whether the consumer should request information on the last-enqueued event on its associated partition, and track that information as events are received. When information about the partitions last-enqueued event is being tracked, each event received from the Event Hubs service will carry metadata about the partition. This results in a small amount of additional network bandwidth consumption that is generally a favorable trade-off when considered against periodically making requests for partition properties using the Event Hub client. It is set to False by default. |
starting_position
|
Start receiving from this event position if there is no checkpoint data for a partition. Checkpoint data will be used if available. This can be a a dict with partition ID as the key and position as the value for individual partitions, or a single value for all partitions. The value type can be str, int or datetime.datetime. Also supported are the values "-1" for receiving from the beginning of the stream, and "@latest" for receiving only new events. |
starting_position_inclusive
|
Determine whether the given starting_position is inclusive(>=) or not (>). True for inclusive and False for exclusive. This can be a dict with partition ID as the key and bool as the value indicating whether the starting_position for a specific partition is inclusive or not. This can also be a single bool value for all starting_position. The default value is False. |
on_error
|
The callback function that will be called when an error is raised during receiving after retry attempts are exhausted, or during the process of load-balancing. The callback takes two parameters: partition_context which contains partition information and error being the exception. partition_context could be None if the error is raised during the process of load-balance. The callback should be defined like: on_error(partition_context, error). The on_error callback will also be called if an unhandled exception is raised during the on_event callback. |
on_partition_initialize
|
The callback function that will be called after a consumer for a certain partition finishes initialization. It would also be called when a new internal partition consumer is created to take over the receiving process for a failed and closed internal partition consumer. The callback takes a single parameter: partition_context which contains the partition information. The callback should be defined like: on_partition_initialize(partition_context). |
on_partition_close
|
The callback function that will be called after a consumer for a certain partition is closed. It would be also called when error is raised during receiving after retry attempts are exhausted. The callback takes two parameters: partition_context which contains partition information and reason for the close. The callback should be defined like: on_partition_close(partition_context, reason). Please refer to CloseReason for the various closing reasons. |
Returns
Type | Description |
---|---|
Examples
Receive events in batches from the EventHub.
logger = logging.getLogger("azure.eventhub")
async def on_event_batch(partition_context, event_batch):
# Put your code here.
# If the operation is i/o intensive, async will have better performance.
logger.info(
"{} events received from partition: {}".format(len(event_batch), partition_context.partition_id)
)
async with consumer:
await consumer.receive_batch(
on_event_batch=on_event_batch,
starting_position="-1", # "-1" is from the beginning of the partition.
)
Azure SDK for Python