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HazelcastMQ Camel

An Apache Camel component implementation for HazelcastMQ supporting Camel's integration framework and Enterprise Integration Patterns (EIP). The component supports configurable consumers and producers including request/reply messaging and concurrent consumers. Unlike Camel's existing JMS component, HazelcastMQ Camel has no dependency on the Spring Framework by building directly on HazelcastMQ Core.

Features

  • Configurable endpoint with producers and consumers
  • Request/reply messaging pattern via temporary or exclusive reply queues
  • Concurrent consumers
  • No dependencies beyond HazelcastMQ Core

Not Implemented Yet

  • Transactions
  • More advanced integration with Camel's asynchronous patterns

Endpoint Format

The endpoint URI can specify if the destination is a queue or a topic such as hazelcastmq:queue:my.outgoing.orders or hazelcastmq:topic:order.processed.event. The destination will be transformed into a standard HzMq destination such as /queue/my.outgoing.orders or /topic/order.processed.event. If queue or topic is not specified, a queue will be assumed.

URI parameters can be used to customize the behavior of the endpoint. The parameters are specified using normal URI parameter syntax such as:

hazelcastmq:queue:my.outgoing.orders?timeToLive=30000&requestTimeout=10000

Endpoint Parameters

Endpoint parameters are specified as URI parameters when defining the endpoint and can be used to customize the behavior of the endpoint for all messages going in or out.

Parameter Type Default Description
concurrentConsumers int 1 The number of concurrent consumers to use when consuming from an endpoint. This should always be set to 1 for topics or duplicate messages may be received.
requestTimeout int 20000 The number of milliseconds to wait for a reply when performing request/reply messaging.
timeToLive int 0 The number of milliseconds that a message will live after being produced by an endpoint. A value of 0 indicates that the message never expires.
replyTo String null The reply-to destination for all replies to messages produced by this endpoint. If not set and a request/reply message is sent, a unique temporary reply queue will be created. The reply queue should be exclusive to avoid having reply messages consumed by other endpoints.

Custom Message Headers

Message headers can be used to customize the behavior of an endpoint on a message by message basis.

Header Type Description
CamelHzMqDestination String If specified, the destination name will be used rather than the destination configured in the endpoint. This allows for a single endpoint to produce messages to multiple destinations by setting different values for this header. Values should be in Camel endpoint syntax such as queue:foo.bar or topic:foo.bar.

Message Conversion

Messages are automatically converted from a HazelcastMQ message to a Camel message and back again by the component using a MessageConverter implementation. The DefaultMessageConverter simply copies all the header values and the message body. If the message has a content-type header of "text/plain" the body is converted to a String when building the Camel message otherwise the body will be a byte[].

A custom message converter can be configured at the component level if custom conversion rules are needed. The message (including the body) can always be converted or modified by the Camel route after message conversion if needed.

Examples

A code example of using HazelcastMQ Camel is shown below. Normally the Camel context, including the HazelcastMQ component is created at application startup using your DI framework of choice.

HazelcastMQConfig mqConfig = new HazelcastMQConfig();
mqConfig.setHazelcastInstance(hz);

HazelcastMQInstance mqInstance = HazelcastMQ
      .newHazelcastMQInstance(mqConfig); 

HazelcastMQCamelConfig mqCamelConfig = new HazelcastMQCamelConfig(); // (1)
mqCamelConfig.setHazelcastMQInstance(mqInstance);

HazelcastMQCamelComponent mqCamelComponent =
    new HazelcastMQCamelComponent(); // (2)
mqCamelComponent.setConfiguration(mqCamelConfig);

// Create the Camel context. This could be done via a Spring XML file.
CamelContext camelContext = new DefaultCamelContext();
camelContext.addComponent("hazelcastmq", mqCamelComponent); // (3)

camelContext.addRoutes(new RouteBuilder() { // (4)
  @Override
  public void configure() {
    from("hazelcastmq:queue:primo.test?timeToLive=10000")
        .to("hazelcastmq:queue:secondo.test");
  }
});

camelContext.start();

HazelcastMQ Camel is configured like any other Camel component:

  1. Create a component configuration
  2. Create the HazelcastMQ Camel component
  3. Register the component with the Camel context
  4. Configure endpoints in routes
  5. Send exchanges to or receive exchanges from the endpoint

Consumer and Producer Route

A simple route can be setup to consume messages from one HazelcastMQ endpoint and produce them to another.

View the example.