Chapter 124. Hazelcast Instance Component

Available as of Camel version 2.7

The Hazelcast instance component is one of Camel Hazelcast Components which allows you to consume join/leave events of the cache instance in the cluster. Hazelcast makes sense in one single "server node", but it’s extremly powerful in a clustered environment.

This endpoint provides no producer!

124.1. Options

The Hazelcast Instance component supports 3 options which are listed below.

NameDescriptionDefaultType

hazelcastInstance (advanced)

The hazelcast instance reference which can be used for hazelcast endpoint. If you don’t specify the instance reference, camel use the default hazelcast instance from the camel-hazelcast instance.

 

HazelcastInstance

hazelcastMode (advanced)

The hazelcast mode reference which kind of instance should be used. If you don’t specify the mode, then the node mode will be the default.

node

String

resolveProperty Placeholders (advanced)

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

boolean

The Hazelcast Instance endpoint is configured using URI syntax:

hazelcast-instance:cacheName

with the following path and query parameters:

124.1.1. Path Parameters (1 parameters):

NameDescriptionDefaultType

cacheName

Required The name of the cache

 

String

124.1.2. Query Parameters (16 parameters):

NameDescriptionDefaultType

reliable (common)

Define if the endpoint will use a reliable Topic struct or not.

false

boolean

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

defaultOperation (consumer)

To specify a default operation to use, if no operation header has been provided.

 

HazelcastOperation

hazelcastInstance (consumer)

The hazelcast instance reference which can be used for hazelcast endpoint.

 

HazelcastInstance

hazelcastInstanceName (consumer)

The hazelcast instance reference name which can be used for hazelcast endpoint. If you don’t specify the instance reference, camel use the default hazelcast instance from the camel-hazelcast instance.

 

String

pollingTimeout (consumer)

Define the polling timeout of the Queue consumer in Poll mode

10000

long

poolSize (consumer)

Define the Pool size for Queue Consumer Executor

1

int

queueConsumerMode (consumer)

Define the Queue Consumer mode: Listen or Poll

Listen

HazelcastQueueConsumer Mode

exceptionHandler (consumer)

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this options 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.

 

ExchangePattern

synchronous (advanced)

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

false

boolean

concurrentConsumers (seda)

To use concurrent consumers polling from the SEDA queue.

1

int

onErrorDelay (seda)

Milliseconds before consumer continues polling after an error has occurred.

1000

int

pollTimeout (seda)

The timeout used when consuming from the SEDA queue. When a timeout occurs, the consumer can check whether it is allowed to continue running. Setting a lower value allows the consumer to react more quickly upon shutdown.

1000

int

transacted (seda)

If set to true then the consumer runs in transaction mode, where the messages in the seda queue will only be removed if the transaction commits, which happens when the processing is complete.

false

boolean

transferExchange (seda)

If set to true the whole Exchange will be transfered. If header or body contains not serializable objects, they will be skipped.

false

boolean

124.2. instance consumer - from("hazelcast-instance:foo")

The instance consumer fires if a new cache instance will join or leave the cluster.

Here’s a sample:

fromF("hazelcast-%sfoo", HazelcastConstants.INSTANCE_PREFIX)
.log("instance...")
.choice()
    .when(header(HazelcastConstants.LISTENER_ACTION).isEqualTo(HazelcastConstants.ADDED))
        .log("...added")
        .to("mock:added")
    .otherwise()
        .log("...removed")
        .to("mock:removed");

Each event provides the following information inside the message header:

Header Variables inside the response message:

NameTypeDescription

CamelHazelcastListenerTime

Long

time of the event in millis

CamelHazelcastListenerType

String

the map consumer sets here "instancelistener"

CamelHazelcastListenerAction

String

type of event - here added or removed.

CamelHazelcastInstanceHost

String

host name of the instance

CamelHazelcastInstancePort

Integer

port number of the instance