Azure Storage Queue Service

Since Camel 3.3

Both producer and consumer are supported

The Azure Storage Queue component supports storing and retrieving the messages to/from Azure Storage Queue service using Azure APIs v12. However in case of versions above v12, we will see if this component can adopt these changes depending on how much breaking changes can result.

Prerequisites

You must have a valid Windows Azure Storage 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-storage-queue</artifactId>
    <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

URI Format

azure-storage-queue://accountName[/queueName][?options]

In case of consumer, accountName and queueName are required. In case of producer, it depends on the operation that being requested, for example if operation is on a service level, e.b: listQueues, only accountName is required, but in case of operation being requested on the queue level, e.g: createQueue, sendMessage.. etc, both accountName and queueName are required.

The queue will be created if it does not already exist. You can append query options to the URI in the following format, ?options=value&option2=value&…​

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.

Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.

Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.

Configuring Endpoint Options

Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.

Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL as a type safe way of configuring endpoints.

A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.

The following two sections lists all the options, firstly for the component followed by the endpoint.

Component Options

The Azure Storage Queue Service component supports 15 options, which are listed below.

Name Description Default Type

configuration (common)

The component configurations.

QueueConfiguration

serviceClient (common)

Autowired Service client to a storage account to interact with the queue service. This client does not hold any state about a particular storage account but is instead a convenient way of sending off appropriate requests to the resource on the service. This client contains all the operations for interacting with a queue account in Azure Storage. Operations allowed by the client are creating, listing, and deleting queues, retrieving and updating properties of the account, and retrieving statistics of the account.

QueueServiceClient

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

createQueue (producer)

When is set to true, the queue will be automatically created when sending messages to the queue.

false

boolean

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

operation (producer)

Queue service operation hint to the producer.

Enum values:

  • listQueues

  • createQueue

  • deleteQueue

  • clearQueue

  • sendMessage

  • deleteMessage

  • receiveMessages

  • peekMessages

  • updateMessage

QueueOperationDefinition

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

boolean

maxMessages (queue)

Maximum number of messages to get, if there are less messages exist in the queue than requested all the messages will be returned. If left empty only 1 message will be retrieved, the allowed range is 1 to 32 messages.

1

Integer

messageId (queue)

The ID of the message to be deleted or updated.

String

popReceipt (queue)

Unique identifier that must match for the message to be deleted or updated.

String

timeout (queue)

An optional timeout applied to the operation. If a response is not returned before the timeout concludes a RuntimeException will be thrown.

Duration

timeToLive (queue)

How long the message will stay alive in the queue. If unset the value will default to 7 days, if -1 is passed the message will not expire. The time to live must be -1 or any positive number. The format should be in this form: PnDTnHnMn.nS., e.g: PT20.345S — parses as 20.345 seconds, P2D — parses as 2 days However, in case you are using EndpointDsl/ComponentDsl, you can do something like Duration.ofSeconds() since these Java APIs are typesafe.

Duration

visibilityTimeout (queue)

The timeout period for how long the message is invisible in the queue. The timeout must be between 1 seconds and 7 days. The format should be in this form: PnDTnHnMn.nS., e.g: PT20.345S — parses as 20.345 seconds, P2D — parses as 2 days However, in case you are using EndpointDsl/ComponentDsl, you can do something like Duration.ofSeconds() since these Java APIs are typesafe.

Duration

accessKey (security)

Access key for the associated azure account name to be used for authentication with azure queue services.

String

credentials (security)

StorageSharedKeyCredential can be injected to create the azure client, this holds the important authentication information.

StorageSharedKeyCredential

Endpoint Options

The Azure Storage Queue Service endpoint is configured using URI syntax:

azure-storage-queue:accountName/queueName

with the following path and query parameters:

Path Parameters (2 parameters)

Name Description Default Type

accountName (common)

Azure account name to be used for authentication with azure queue services.

String

queueName (common)

The queue resource name.

String

Query Parameters (31 parameters)

Name Description Default Type

serviceClient (common)

Autowired Service client to a storage account to interact with the queue service. This client does not hold any state about a particular storage account but is instead a convenient way of sending off appropriate requests to the resource on the service. This client contains all the operations for interacting with a queue account in Azure Storage. Operations allowed by the client are creating, listing, and deleting queues, retrieving and updating properties of the account, and retrieving statistics of the account.

QueueServiceClient

sendEmptyMessageWhenIdle (consumer)

If the polling consumer did not poll any files, you can enable this option to send an empty message (no body) instead.

false

boolean

bridgeErrorHandler (consumer (advanced))

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

exceptionHandler (consumer (advanced))

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 (advanced))

Sets the exchange pattern when the consumer creates an exchange.

Enum values:

  • InOnly

  • InOut

  • InOptionalOut

ExchangePattern

pollStrategy (consumer (advanced))

A pluggable org.apache.camel.PollingConsumerPollingStrategy allowing you to provide your custom implementation to control error handling usually occurred during the poll operation before an Exchange have been created and being routed in Camel.

PollingConsumerPollStrategy

createQueue (producer)

When is set to true, the queue will be automatically created when sending messages to the queue.

false

boolean

operation (producer)

Queue service operation hint to the producer.

Enum values:

  • listQueues

  • createQueue

  • deleteQueue

  • clearQueue

  • sendMessage

  • deleteMessage

  • receiveMessages

  • peekMessages

  • updateMessage

QueueOperationDefinition

lazyStartProducer (producer (advanced))

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

maxMessages (queue)

Maximum number of messages to get, if there are less messages exist in the queue than requested all the messages will be returned. If left empty only 1 message will be retrieved, the allowed range is 1 to 32 messages.

1

Integer

messageId (queue)

The ID of the message to be deleted or updated.

String

popReceipt (queue)

Unique identifier that must match for the message to be deleted or updated.

String

timeout (queue)

An optional timeout applied to the operation. If a response is not returned before the timeout concludes a RuntimeException will be thrown.

Duration

timeToLive (queue)

How long the message will stay alive in the queue. If unset the value will default to 7 days, if -1 is passed the message will not expire. The time to live must be -1 or any positive number. The format should be in this form: PnDTnHnMn.nS., e.g: PT20.345S — parses as 20.345 seconds, P2D — parses as 2 days However, in case you are using EndpointDsl/ComponentDsl, you can do something like Duration.ofSeconds() since these Java APIs are typesafe.

Duration

visibilityTimeout (queue)

The timeout period for how long the message is invisible in the queue. The timeout must be between 1 seconds and 7 days. The format should be in this form: PnDTnHnMn.nS., e.g: PT20.345S — parses as 20.345 seconds, P2D — parses as 2 days However, in case you are using EndpointDsl/ComponentDsl, you can do something like Duration.ofSeconds() since these Java APIs are typesafe.

Duration

backoffErrorThreshold (scheduler)

The number of subsequent error polls (failed due some error) that should happen before the backoffMultipler should kick-in.

int

backoffIdleThreshold (scheduler)

The number of subsequent idle polls that should happen before the backoffMultipler should kick-in.

int

backoffMultiplier (scheduler)

To let the scheduled polling consumer backoff if there has been a number of subsequent idles/errors in a row. The multiplier is then the number of polls that will be skipped before the next actual attempt is happening again. When this option is in use then backoffIdleThreshold and/or backoffErrorThreshold must also be configured.

int

delay (scheduler)

Milliseconds before the next poll.

500

long

greedy (scheduler)

If greedy is enabled, then the ScheduledPollConsumer will run immediately again, if the previous run polled 1 or more messages.

false

boolean

initialDelay (scheduler)

Milliseconds before the first poll starts.

1000

long

repeatCount (scheduler)

Specifies a maximum limit of number of fires. So if you set it to 1, the scheduler will only fire once. If you set it to 5, it will only fire five times. A value of zero or negative means fire forever.

0

long

runLoggingLevel (scheduler)

The consumer logs a start/complete log line when it polls. This option allows you to configure the logging level for that.

Enum values:

  • TRACE

  • DEBUG

  • INFO

  • WARN

  • ERROR

  • OFF

TRACE

LoggingLevel

scheduledExecutorService (scheduler)

Allows for configuring a custom/shared thread pool to use for the consumer. By default each consumer has its own single threaded thread pool.

ScheduledExecutorService

scheduler (scheduler)

To use a cron scheduler from either camel-spring or camel-quartz component. Use value spring or quartz for built in scheduler.

none

Object

schedulerProperties (scheduler)

To configure additional properties when using a custom scheduler or any of the Quartz, Spring based scheduler.

Map

startScheduler (scheduler)

Whether the scheduler should be auto started.

true

boolean

timeUnit (scheduler)

Time unit for initialDelay and delay options.

Enum values:

  • NANOSECONDS

  • MICROSECONDS

  • MILLISECONDS

  • SECONDS

  • MINUTES

  • HOURS

  • DAYS

MILLISECONDS

TimeUnit

useFixedDelay (scheduler)

Controls if fixed delay or fixed rate is used. See ScheduledExecutorService in JDK for details.

true

boolean

accessKey (security)

Access key for the associated azure account name to be used for authentication with azure queue services.

String

credentials (security)

StorageSharedKeyCredential can be injected to create the azure client, this holds the important authentication information.

StorageSharedKeyCredential

Required information options:

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

  • Provide accountName and accessKey for your Azure account, this is the simplest way to get started. The accessKey can be generated through your Azure portal.

  • Provide a StorageSharedKeyCredential instance which can be provided into credentials option.

  • Provide a QueueServiceClient instance which can be provided into serviceClient. Note: You don’t need to create a specific client, e.g: QueueClient, the QueueServiceClient represents the upper level which can be used to retrieve lower level clients.

Usage

For example in order to get a message content from the queue messageQueue in the storageAccount storage account and, use the following snippet:

from("azure-storage-queue://storageAccount/messageQueue?accessKey=yourAccessKey").
to("file://queuedirectory");

Message Headers

The Azure Storage Queue Service component supports 16 message header(s), which is/are listed below:

Name Description Default Type

CamelAzureStorageQueueRawHttpHeaders (common)

Constant: RAW_HTTP_HEADERS

Returns non-parsed httpHeaders that can be used by the user.

HttpHeaders

CamelAzureStorageQueueMetadata (producer)

Constant: METADATA

(createQueue) Metadata to associate with the queue.

Map

CamelAzureStorageQueueMessageId (common)

Constant: MESSAGE_ID

The ID of the message.

String

CamelAzureStorageQueueInsertionTime (common)

Constant: INSERTION_TIME

The time the Message was inserted into the Queue.

OffsetDateTime

CamelAzureStorageQueueExpirationTime (common)

Constant: EXPIRATION_TIME

The time that the Message will expire and be automatically deleted.

OffsetDateTime

CamelAzureStorageQueuePopReceipt (producer)

Constant: POP_RECEIPT

(deleteMessage, updateMessage) Unique identifier that must match for the message to be deleted or updated. If deletion fails using this pop receipt then the message has been dequeued by another client.

String

CamelAzureStorageQueueTimeNextVisible (common)

Constant: TIME_NEXT_VISIBLE

The time that the message will again become visible in the Queue.

OffsetDateTime

CamelAzureStorageQueueDequeueCount (common)

Constant: DEQUEUE_COUNT

The number of times the message has been dequeued.

long

CamelAzureStorageQueueOperation (producer)

Constant: QUEUE_OPERATION

(All) Specify the producer operation to execute, please see the doc on this page related to producer operation.

Enum values:

  • listQueues

  • createQueue

  • deleteQueue

  • clearQueue

  • sendMessage

  • deleteMessage

  • receiveMessages

  • peekMessages

  • updateMessage

QueueOperationDefinition

CamelAzureStorageQueueName (producer)

Constant: QUEUE_NAME

(All) Override the queue name.

String

CamelAzureStorageQueueSegmentOptions (producer)

Constant: QUEUES_SEGMENT_OPTIONS

(listQueues) Options for listing queues.

QueuesSegmentOptions

CamelAzureStorageQueueTimeout (producer)

Constant: TIMEOUT

(All) An optional timeout value beyond which a RuntimeException will be raised.

Duration

CamelAzureStorageQueueMaxMessages (producer)

Constant: MAX_MESSAGES

(receiveMessages, peekMessages) Maximum number of messages to get, if there are less messages exist in the queue than requested all the messages will be returned. If left empty only 1 message will be retrieved, the allowed range is 1 to 32 messages.

Integer

CamelAzureStorageQueueVisibilityTimeout (producer)

Constant: VISIBILITY_TIMEOUT

(sendMessage, receiveMessages, updateMessage) The timeout period for how long the message is invisible in the queue. If unset the value will default to 0 and the message will be instantly visible. The timeout must be between 0 seconds and 7 days.

Duration

CamelAzureStorageQueueTimeToLive (producer)

Constant: TIME_TO_LIVE

(sendMessage) How long the message will stay alive in the queue. If unset the value will default to 7 days, if -1 is passed the message will not expire. The time to live must be -1 or any positive number.

Duration

CamelAzureStorageQueueCreateQueue (producer)

Constant: CREATE_QUEUE

(sendMessage) When is set to true, the queue will be automatically created when sending messages to the queue.

boolean

Advanced Azure Storage Queue configuration

If your Camel Application is running behind a firewall or if you need to have more control over the QueueServiceClient instance configuration, you can create your own instance:

StorageSharedKeyCredential credential = new StorageSharedKeyCredential("yourAccountName", "yourAccessKey");
String uri = String.format("https://%s.queue.core.windows.net", "yourAccountName");

QueueServiceClient client = new QueueServiceClientBuilder()
                          .endpoint(uri)
                          .credential(credential)
                          .buildClient();
// This is camel context
context.getRegistry().bind("client", client);

Then refer to this instance in your Camel azure-storage-queue component configuration:

from("azure-storage-queue://cameldev/queue1?serviceClient=#client")
.to("file://outputFolder?fileName=output.txt&fileExist=Append");

Automatic detection of QueueServiceClient client in registry

The component is capable of detecting the presence of an QueueServiceClient 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.

Azure Storage Queue Producer operations

Camel Azure Storage Queue component provides wide range of operations on the producer side:

Operations on the service level

For these operations, accountName is required.

Operation Description

listQueues

Lists the queues in the storage account that pass the filter starting at the specified marker.

Operations on the queue level

For these operations, accountName and queueName are required.

Operation Description

createQueue

Creates a new queue.

deleteQueue

Permanently deletes the queue.

clearQueue

Deletes all messages in the queue..

sendMessage

Default Producer Operation Sends a message with a given time-to-live and a timeout period where the message is invisible in the queue. The message text is evaluated from the exchange message body. By default, if the queue doesn`t exist, it will create an empty queue first. If you want to disable this, set the config createQueue or header CamelAzureStorageQueueCreateQueue to false.

deleteMessage

Deletes the specified message in the queue.

receiveMessages

Retrieves up to the maximum number of messages from the queue and hides them from other operations for the timeout period. However it will not dequeue the message from the queue due to reliability reasons.

peekMessages

Peek messages from the front of the queue up to the maximum number of messages.

updateMessage

Updates the specific message in the queue with a new message and resets the visibility timeout. The message text is evaluated from the exchange message body.

Refer to the example section in this page to learn how to use these operations into your camel application.

Consumer Examples

To consume a queue into a file component with maximum 5 messages in one batch, this can be done like this:

from("azure-storage-queue://cameldev/queue1?serviceClient=#client&maxMessages=5")
.to("file://outputFolder?fileName=output.txt&fileExist=Append");

Producer Operations Examples

  • listQueues:

from("direct:start")
    .process(exchange -> {
      // set the header you want the producer to evaluate, refer to the previous
      // section to learn about the headers that can be set
      // e.g, to only returns list of queues with 'awesome' prefix:
      exchange.getIn().setHeader(QueueConstants.QUEUES_SEGMENT_OPTIONS, new QueuesSegmentOptions().setPrefix("awesome"));
     })
    .to("azure-storage-queue://cameldev?serviceClient=#client&operation=listQueues")
    .log("${body}")
    .to("mock:result");

  • createQueue:

from("direct:start")
    .process(exchange -> {
      // set the header you want the producer to evaluate, refer to the previous
      // section to learn about the headers that can be set
      // e.g:
      exchange.getIn().setHeader(QueueConstants.QUEUE_NAME, "overrideName");
     })
    .to("azure-storage-queue://cameldev/test?serviceClient=#client&operation=createQueue");

  • deleteQueue:

from("direct:start")
    .process(exchange -> {
      // set the header you want the producer to evaluate, refer to the previous
      // section to learn about the headers that can be set
      // e.g:
      exchange.getIn().setHeader(QueueConstants.QUEUE_NAME, "overrideName");
     })
    .to("azure-storage-queue://cameldev/test?serviceClient=#client&operation=deleteQueue");

  • clearQueue:

from("direct:start")
    .process(exchange -> {
      // set the header you want the producer to evaluate, refer to the previous
      // section to learn about the headers that can be set
      // e.g:
      exchange.getIn().setHeader(QueueConstants.QUEUE_NAME, "overrideName");
     })
    .to("azure-storage-queue://cameldev/test?serviceClient=#client&operation=clearQueue");

  • sendMessage:

from("direct:start")
    .process(exchange -> {
      // set the header you want the producer to evaluate, refer to the previous
      // section to learn about the headers that can be set
      // e.g:
      exchange.getIn().setBody("message to send");
      // we set a visibility of 1min
      exchange.getIn().setHeader(QueueConstants.VISIBILITY_TIMEOUT, Duration.ofMinutes(1));
     })
    .to("azure-storage-queue://cameldev/test?serviceClient=#client");

  • deleteMessage:

from("direct:start")
    .process(exchange -> {
      // set the header you want the producer to evaluate, refer to the previous
      // section to learn about the headers that can be set
      // e.g:
      // Mandatory header:
      exchange.getIn().setHeader(QueueConstants.MESSAGE_ID, "1");
      // Mandatory header:
      exchange.getIn().setHeader(QueueConstants.POP_RECEIPT, "PAAAAHEEERXXX-1");
     })
    .to("azure-storage-queue://cameldev/test?serviceClient=#client&operation=deleteMessage");

  • receiveMessages:

from("direct:start")
    .to("azure-storage-queue://cameldev/test?serviceClient=#client&operation=receiveMessages")
    .process(exchange -> {
        final List<QueueMessageItem> messageItems = exchange.getMessage().getBody(List.class);
        messageItems.forEach(messageItem -> System.out.println(messageItem.getMessageText()));
    })
   .to("mock:result");

  • peekMessages:

from("direct:start")
    .to("azure-storage-queue://cameldev/test?serviceClient=#client&operation=peekMessages")
    .process(exchange -> {
        final List<PeekedMessageItem> messageItems = exchange.getMessage().getBody(List.class);
        messageItems.forEach(messageItem -> System.out.println(messageItem.getMessageText()));
    })
   .to("mock:result");

  • updateMessage:

from("direct:start")
   .process(exchange -> {
       // set the header you want the producer to evaluate, refer to the previous
       // section to learn about the headers that can be set
       // e.g:
       exchange.getIn().setBody("new message text");
       // Mandatory header:
       exchange.getIn().setHeader(QueueConstants.MESSAGE_ID, "1");
       // Mandatory header:
       exchange.getIn().setHeader(QueueConstants.POP_RECEIPT, "PAAAAHEEERXXX-1");
       // Mandatory header:
       exchange.getIn().setHeader(QueueConstants.VISIBILITY_TIMEOUT, Duration.ofMinutes(1));
    })
    .to("azure-storage-queue://cameldev/test?serviceClient=#client&operation=updateMessage");

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 -DaccountName=myacc -DaccessKey=mykey

Whereby accountName is your Azure account name and accessKey is the access key being generated from Azure portal.