Azure Event Hubs

Since Camel 3.5

Both producer and consumer are supported

The Azure Event Hubs used to integrate Azure Event Hubs using AMQP protocol. Azure EventHubs is a highly scalable publish-subscribe service that can ingest millions of events per second and stream them to multiple consumers.

Besides AMQP protocol support, Event Hubs as well supports Kafka and HTTPS protocols. Therefore, you can use as well Camel Kafka component to produce and consume to Azure Event Hubs. You can lean more here.

Prerequisites

You must have a valid Windows Azure Event Hubs account. More information is available at Azure Documentation Portal.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-azure-eventhubs</artifactId>
    <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

URI Format

azure-eventhubs://[namespace/eventHubName][?options]

In case you supply the connectionString, namespace and eventHubName are not required as these options already included in the connectionString

For example in order consume event from EventHub, use the following snippet:

from("azure-eventhubs:/camel/camelHub?sharedAccessName=SASaccountName&sharedAccessKey=SASaccessKey&blobAccountName=accountName&blobAccessKey=accessKey&blobContainerName=containerName").
to("file://queuedirectory");

URI Options

The Azure Event Hubs endpoint is configured using URI syntax:

azure-eventhubs:namespace/eventHubName

with the following path and query parameters:

Path Parameters (2 parameters):

Name Description Default Type

namespace

EventHubs namespace created in Azure Portal

String

eventHubName

EventHubs name under a specific namcespace

String

Query Parameters (23 parameters):

Name Description Default Type

amqpRetryOptions (common)

Sets the retry policy for EventHubAsyncClient. If not specified, the default retry options are used.

AmqpRetryOptions

amqpTransportType (common)

Sets the transport type by which all the communication with Azure Event Hubs occurs. Default value is AmqpTransportType#AMQP. There are 2 enums and the value can be one of: Amqp, AmqpWebSockets

AMQP

AmqpTransportType

autoDiscoverClient (common)

Setting the autoDiscoverClient mechanism, if true, the component will look for a client instance in the registry automatically otherwise it will skip that checking.

true

boolean

blobAccessKey (consumer)

In case you chose the default BlobCheckpointStore, this sets access key for the associated azure account name to be used for authentication with azure blob services

String

blobAccountName (consumer)

In case you chose the default BlobCheckpointStore, this sets Azure account name to be used for authentication with azure blob services.

String

blobContainerName (consumer)

In case you chose the default BlobCheckpointStore, this sets the blob container that shall be used by the BlobCheckpointStore to store the checkpoint offsets

String

blobStorageSharedKeyCredential (consumer)

In case you chose the default BlobCheckpointStore, StorageSharedKeyCredential can be injected to create the azure client, this holds the important authentication information

StorageSharedKeyCredential

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

checkpointStore (consumer)

Sets the CheckpointStore the EventProcessorClient will use for storing partition ownership and checkpoint information. Users can, optionally, provide their own implementation of CheckpointStore which will store ownership and checkpoint information. By default it set to use com.azure.messaging.eventhubs.checkpointstore.blob.BlobCheckpointStore which stores all checkpoint offsets into Azure Blob Storage

BlobCheckpointStore

CheckpointStore

consumerGroupName (consumer)

Sets the name of the consumer group this consumer is associated with. Events are read in the context of this group. The name of the consumer group that is created by default is {link #DEFAULT_CONSUMER_GROUP_NAME $Default}.

$Default

String

eventPosition (consumer)

Sets the map containing the event position to use for each partition if a checkpoint for the partition does not exist in CheckpointStore. This map is keyed off of the partition id. If there is no checkpoint in CheckpointStore and there is no entry in this map, the processing of the partition will start from {link EventPosition#latest() latest} position.

Map

prefetchCount (consumer)

Sets the count used by the receiver to control the number of events the Event Hub consumer will actively receive and queue locally without regard to whether a receive operation is currently active.

500

int

exceptionHandler (consumer)

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored.

ExceptionHandler

exchangePattern (consumer)

Sets the exchange pattern when the consumer creates an exchange. There are 3 enums and the value can be one of: InOnly, InOut, InOptionalOut

ExchangePattern

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

partitionId (producer)

Sets the identifier of the Event Hub partition that the events will be sent to. If the identifier is not specified, the Event Hubs service will be responsible for routing events that are sent to an available partition.

String

partitionKey (producer)

Sets a hashing key to be provided for the batch of events, which instructs the Event Hubs service to map this key to a specific partition. The selection of a partition is stable for a given partition hashing key. Should any other batches of events be sent using the same exact partition hashing key, the Event Hubs service will route them all to the same partition. This should be specified only when there is a need to group events by partition, but there is flexibility into which partition they are routed. If ensuring that a batch of events is sent only to a specific partition, it is recommended that the {link #setPartitionId(String) identifier of the position be specified directly} when sending the batch.

String

producerAsyncClient (producer)

Sets the EventHubProducerAsyncClient.An asynchronous producer responsible for transmitting EventData to a specific Event Hub, grouped together in batches. Depending on the options specified when creating an {linkEventDataBatch}, the events may be automatically routed to an available partition or specific to a partition. Use by this component to produce the data in camel producer.

EventHubProducerAsyncClient

basicPropertyBinding (advanced)

Whether the endpoint should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities

false

boolean

synchronous (advanced)

Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).

false

boolean

connectionString (security)

Instead of supplying namespace, sharedAccessKey, sharedAccessName …​ etc, you can just supply the connection string for your eventHub. The connection string for EventHubs already include all the necessary information to connection to your EventHub. To learn on how to generate the connection string, take a look at this documentation: https://docs.microsoft.com/en-us/azure/event-hubs/event-hubs-get-connection-string

String

sharedAccessKey (security)

The generated value for the SharedAccessName

String

sharedAccessName (security)

The name you chose for your EventHubs SAS keys

String

The Azure Event Hubs component supports 21 options, which are listed below.

Name Description Default Type

amqpRetryOptions (common)

Sets the retry policy for EventHubAsyncClient. If not specified, the default retry options are used.

AmqpRetryOptions

amqpTransportType (common)

Sets the transport type by which all the communication with Azure Event Hubs occurs. Default value is AmqpTransportType#AMQP. There are 2 enums and the value can be one of: Amqp, AmqpWebSockets

AMQP

AmqpTransportType

autoDiscoverClient (common)

Setting the autoDiscoverClient mechanism, if true, the component will look for a client instance in the registry automatically otherwise it will skip that checking.

true

boolean

configuration (common)

The component configurations

EventHubsConfiguration

blobAccessKey (consumer)

In case you chose the default BlobCheckpointStore, this sets access key for the associated azure account name to be used for authentication with azure blob services

String

blobAccountName (consumer)

In case you chose the default BlobCheckpointStore, this sets Azure account name to be used for authentication with azure blob services.

String

blobContainerName (consumer)

In case you chose the default BlobCheckpointStore, this sets the blob container that shall be used by the BlobCheckpointStore to store the checkpoint offsets

String

blobStorageSharedKeyCredential (consumer)

In case you chose the default BlobCheckpointStore, StorageSharedKeyCredential can be injected to create the azure client, this holds the important authentication information

StorageSharedKeyCredential

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

checkpointStore (consumer)

Sets the CheckpointStore the EventProcessorClient will use for storing partition ownership and checkpoint information. Users can, optionally, provide their own implementation of CheckpointStore which will store ownership and checkpoint information. By default it set to use com.azure.messaging.eventhubs.checkpointstore.blob.BlobCheckpointStore which stores all checkpoint offsets into Azure Blob Storage

BlobCheckpointStore

CheckpointStore

consumerGroupName (consumer)

Sets the name of the consumer group this consumer is associated with. Events are read in the context of this group. The name of the consumer group that is created by default is {link #DEFAULT_CONSUMER_GROUP_NAME $Default}.

$Default

String

eventPosition (consumer)

Sets the map containing the event position to use for each partition if a checkpoint for the partition does not exist in CheckpointStore. This map is keyed off of the partition id. If there is no checkpoint in CheckpointStore and there is no entry in this map, the processing of the partition will start from {link EventPosition#latest() latest} position.

Map

prefetchCount (consumer)

Sets the count used by the receiver to control the number of events the Event Hub consumer will actively receive and queue locally without regard to whether a receive operation is currently active.

500

int

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

partitionId (producer)

Sets the identifier of the Event Hub partition that the events will be sent to. If the identifier is not specified, the Event Hubs service will be responsible for routing events that are sent to an available partition.

String

partitionKey (producer)

Sets a hashing key to be provided for the batch of events, which instructs the Event Hubs service to map this key to a specific partition. The selection of a partition is stable for a given partition hashing key. Should any other batches of events be sent using the same exact partition hashing key, the Event Hubs service will route them all to the same partition. This should be specified only when there is a need to group events by partition, but there is flexibility into which partition they are routed. If ensuring that a batch of events is sent only to a specific partition, it is recommended that the {link #setPartitionId(String) identifier of the position be specified directly} when sending the batch.

String

producerAsyncClient (producer)

Sets the EventHubProducerAsyncClient.An asynchronous producer responsible for transmitting EventData to a specific Event Hub, grouped together in batches. Depending on the options specified when creating an {linkEventDataBatch}, the events may be automatically routed to an available partition or specific to a partition. Use by this component to produce the data in camel producer.

EventHubProducerAsyncClient

basicPropertyBinding (advanced)

Deprecated Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities

false

boolean

connectionString (security)

Instead of supplying namespace, sharedAccessKey, sharedAccessName …​ etc, you can just supply the connection string for your eventHub. The connection string for EventHubs already include all the necessary information to connection to your EventHub. To learn on how to generate the connection string, take a look at this documentation: https://docs.microsoft.com/en-us/azure/event-hubs/event-hubs-get-connection-string

String

sharedAccessKey (security)

The generated value for the SharedAccessName

String

sharedAccessName (security)

The name you chose for your EventHubs SAS keys

String

Authentication Information

To use this component, you have 3 options in order to provide the required Azure authentication information:

  • Provide sharedAccessName and sharedAccessKey for your Azure Event Hubs account. The sharedAccessKey can be generated through your Event Hubs Azure portal.

  • Provide connectionString string, if you provide the connection string, you don’t supply namespace, eventHubName, sharedAccessKey and sharedAccessName as these data already included in the connectionString, therefore is the simplest option to get started. Learn more here on how to generate the connection string.

  • Provide a EventHubProducerAsyncClient instance which can be provided into producerAsyncClient. However, this is only possible for camel producer, for the camel consumer, is not possible to inject the client due to some design constrain by the EventProcessorClient.

Checkpoint Store Information

A checkpoint store stores and retrieves partition ownership information and checkpoint details for each partition in a given consumer group of an event hub instance. Users are not meant to implement an CheckpointStore. Users are expected to choose existing implementations of this interface, instantiate it, and pass it to the component through checkpointStore option. Users are not expected to use any of the methods on a checkpoint store, these are used internally by the client.

Having said that, if the user does not pass any CheckpointStore implementation, the component will fallback to use BlobCheckpointStore to store the checkpoint info in Azure Blob Storage account. If you chose to use the default BlobCheckpointStore, you will need to supply the following options:

  • blobAccountName: It sets Azure account name to be used for authentication with azure blob services.

  • blobAccessKey : It sets access key for the associated azure account name to be used for authentication with azure blob services.

  • blobContainerName : It sets the blob container that shall be used by the BlobCheckpointStore to store the checkpoint offsets.

Async Consumer and Producer

This component implements the async Consumer and producer.

This allows camel route to consume and produce events asynchronously without blocking any threads.

Usage

Message headers evaluated by the component producer

Header Variable Name Type Description

CamelAzureEventHubsPartitionKey

EventHubsConstants.PARTITION_KEY

String

Overrides the hashing key to be provided for the batch of events, which instructs the Event Hubs service to map this key to a specific partition.

CamelAzureEventHubsPartitionId

EventHubsConstants.PARTITION_ID

String

Overrides the identifier of the Event Hub partition that the {link EventData events} will be sent to.

Message headers set by the component consumer

Header Variable Name Type Description

CamelAzureEventHubsPartitionKey

EventHubsConstants.PARTITION_KEY

String

It sets the partition hashing key if it was set when originally publishing the event. If it exists, this value was used to compute a hash to select a partition to send the message to. This is only present on a received {@link EventData}.

CamelAzureEventHubsPartitionId

EventHubsConstants.PARTITION_ID

String

It sets the partition id of the Event Hub.

CamelAzureEventHubsOffset

EventHubsConstants.OFFSET

Long

It sets the offset of the event when it was received from the associated Event Hub partition. This is only present on a received {@link EventData}.

CamelAzureEventHubsEnqueuedTime

EventHubsConstants.ENQUEUED_TIME

Instant

It sets the instant, in UTC, of when the event was enqueued in the Event Hub partition. This is only present on a received {@link EventData}.

CamelAzureEventHubsSequenceNumber

EventHubsConstants.SEQUENCE_NUMBER

Long

It sets the sequence number assigned to the event when it was enqueued in the associated Event Hub partition. This is unique for every message received in the Event Hub partition. This is only present on a received {@link EventData}.

Message body type

The component’s producer expects the data in the message body to be in byte[]. This allows the user to utilize Camel TypeConverter to marshal/unmarshal data with ease. The same goes as well for the component’s consumer, it will set the encoded data as byte[] in the message body.

Automatic detection of EventHubProducerAsyncClient client in registry

The component is capable of detecting the presence of an EventHubProducerAsyncClient bean into the registry. If it’s the only instance of that type it will be used as client and you won’t have to define it as uri parameter, like the example above. This may be really useful for smarter configuration of the endpoint.

Consumer Example

The example below will unmarshal the events that was originally produced in JSON:

from("azure-eventhubs:?connectionString=RAW({{connectionString}})"&blobContainerName=containerTest&eventPosition=#eventPosition"
    +"&blobAccountName={{blobAccountName}}&blobAccessKey=RAW({{blobAccessKey}})")
.unmarshal().json(JsonLibrary.Jackson)
.to(result);

Producer Example

The example below will send events as String to EventHubs:

from("direct:start")
.process(exchange -> {
        exchange.getIn().setHeader(EventHubsConstants.PARTITION_ID, firstPartition);
        exchange.getIn().setBody("test event");
})
.to("azure-eventhubs:?connectionString=RAW({{connectionString}})"

Also, the component supports as well aggregation of messages by sending events as iterable of either Exchanges/Messages or normal data (e.g: list of Strings). For example:

from("direct:start")
.process(exchange -> {
        final List<String> messages = new LinkedList<>();
        messages.add("Test String Message 1");
        messages.add("Test String Message 2");

        exchange.getIn().setHeader(EventHubsConstants.PARTITION_ID, firstPartition);
        exchange.getIn().setBody(messages);
})
.to("azure-eventhubs:?connectionString=RAW({{connectionString}})"

Development Notes (Important)

When developing on this component, you will need to obtain your Azure accessKey in order to run the integration tests. In addition to the mocked unit tests you will need to run the integration tests with every change you make or even client upgrade as the Azure client can break things even on minor versions upgrade. To run the integration tests, on this component directory, run the following maven command:

mvn verify -PfullTests -DconnectionString=string -DblobAccountName=blob -DblobAccessKey=key

Whereby blobAccountName is your Azure account name and blobAccessKey is the access key being generated from Azure portal and connectionString is the eventHub connection string.

Spring Boot Auto-Configuration

When using azure-eventhubs with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-azure-eventhubs-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 22 options, which are listed below.

Name Description Default Type

camel.component.azure-eventhubs.amqp-retry-options

Sets the retry policy for EventHubAsyncClient. If not specified, the default retry options are used. The option is a com.azure.core.amqp.AmqpRetryOptions type.

String

camel.component.azure-eventhubs.amqp-transport-type

Sets the transport type by which all the communication with Azure Event Hubs occurs. Default value is AmqpTransportType#AMQP.

AmqpTransportType

camel.component.azure-eventhubs.auto-discover-client

Setting the autoDiscoverClient mechanism, if true, the component will look for a client instance in the registry automatically otherwise it will skip that checking.

true

Boolean

camel.component.azure-eventhubs.blob-access-key

In case you chose the default BlobCheckpointStore, this sets access key for the associated azure account name to be used for authentication with azure blob services

String

camel.component.azure-eventhubs.blob-account-name

In case you chose the default BlobCheckpointStore, this sets Azure account name to be used for authentication with azure blob services.

String

camel.component.azure-eventhubs.blob-container-name

In case you chose the default BlobCheckpointStore, this sets the blob container that shall be used by the BlobCheckpointStore to store the checkpoint offsets

String

camel.component.azure-eventhubs.blob-storage-shared-key-credential

In case you chose the default BlobCheckpointStore, StorageSharedKeyCredential can be injected to create the azure client, this holds the important authentication information. The option is a com.azure.storage.common.StorageSharedKeyCredential type.

String

camel.component.azure-eventhubs.bridge-error-handler

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

Boolean

camel.component.azure-eventhubs.checkpoint-store

Sets the CheckpointStore the EventProcessorClient will use for storing partition ownership and checkpoint information. Users can, optionally, provide their own implementation of CheckpointStore which will store ownership and checkpoint information. By default it set to use com.azure.messaging.eventhubs.checkpointstore.blob.BlobCheckpointStore which stores all checkpoint offsets into Azure Blob Storage. The option is a com.azure.messaging.eventhubs.CheckpointStore type.

String

camel.component.azure-eventhubs.configuration

The component configurations. The option is a org.apache.camel.component.azure.eventhubs.EventHubsConfiguration type.

String

camel.component.azure-eventhubs.connection-string

Instead of supplying namespace, sharedAccessKey, sharedAccessName …​ etc, you can just supply the connection string for your eventHub. The connection string for EventHubs already include all the necessary information to connection to your EventHub. To learn on how to generate the connection string, take a look at this documentation: https://docs.microsoft.com/en-us/azure/event-hubs/event-hubs-get-connection-string

String

camel.component.azure-eventhubs.consumer-group-name

Sets the name of the consumer group this consumer is associated with. Events are read in the context of this group. The name of the consumer group that is created by default is {link #DEFAULT_CONSUMER_GROUP_NAME $Default}.

$Default

String

camel.component.azure-eventhubs.enabled

Whether to enable auto configuration of the azure-eventhubs component. This is enabled by default.

Boolean

camel.component.azure-eventhubs.event-position

Sets the map containing the event position to use for each partition if a checkpoint for the partition does not exist in CheckpointStore. This map is keyed off of the partition id. If there is no checkpoint in CheckpointStore and there is no entry in this map, the processing of the partition will start from {link EventPosition#latest() latest} position.

Map

camel.component.azure-eventhubs.lazy-start-producer

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

Boolean

camel.component.azure-eventhubs.partition-id

Sets the identifier of the Event Hub partition that the events will be sent to. If the identifier is not specified, the Event Hubs service will be responsible for routing events that are sent to an available partition.

String

camel.component.azure-eventhubs.partition-key

Sets a hashing key to be provided for the batch of events, which instructs the Event Hubs service to map this key to a specific partition. The selection of a partition is stable for a given partition hashing key. Should any other batches of events be sent using the same exact partition hashing key, the Event Hubs service will route them all to the same partition. This should be specified only when there is a need to group events by partition, but there is flexibility into which partition they are routed. If ensuring that a batch of events is sent only to a specific partition, it is recommended that the {link #setPartitionId(String) identifier of the position be specified directly} when sending the batch.

String

camel.component.azure-eventhubs.prefetch-count

Sets the count used by the receiver to control the number of events the Event Hub consumer will actively receive and queue locally without regard to whether a receive operation is currently active.

500

Integer

camel.component.azure-eventhubs.producer-async-client

Sets the EventHubProducerAsyncClient.An asynchronous producer responsible for transmitting EventData to a specific Event Hub, grouped together in batches. Depending on the options specified when creating an {linkEventDataBatch}, the events may be automatically routed to an available partition or specific to a partition. Use by this component to produce the data in camel producer. The option is a com.azure.messaging.eventhubs.EventHubProducerAsyncClient type.

String

camel.component.azure-eventhubs.shared-access-key

The generated value for the SharedAccessName

String

camel.component.azure-eventhubs.shared-access-name

The name you chose for your EventHubs SAS keys

String

camel.component.azure-eventhubs.basic-property-binding

Deprecated Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities

false

Boolean