Chapter 81. Direct VM Component

Available as of Camel version 2.10

The direct-vm: component provides direct, synchronous invocation of any consumers in the JVM when a producer sends a message exchange.
This endpoint can be used to connect existing routes in the same camel context, as well from other camel contexts in the same JVM.

This component differs from the Direct component in that Direct-VM supports communication across CamelContext instances - so you can use this mechanism to communicate across web applications (provided that camel-core.jar is on the system/boot classpath).

At runtime you can swap in new consumers, by stopping the existing consumer(s) and start new consumers.
But at any given time there can be at most only one active consumer for a given endpoint.

This component allows also to connect routes deployed in different OSGI Bundles as you can see here after. Even if they are running in different bundles, the camel routes will use
the same thread. That autorises to develop applications using Transactions - Tx.

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81.1. URI format

direct-vm:someName

Where someName can be any string to uniquely identify the endpoint

81.2. Options

The Direct VM component supports 5 options which are listed below.

NameDescriptionDefaultType

block (producer)

If sending a message to a direct endpoint which has no active consumer, then we can tell the producer to block and wait for the consumer to become active.

true

boolean

timeout (producer)

The timeout value to use if block is enabled.

30000

long

headerFilterStrategy (advanced)

Sets a HeaderFilterStrategy that will only be applied on producer endpoints (on both directions: request and response). Default value: none.

 

HeaderFilterStrategy

propagateProperties (advanced)

Whether to propagate or not properties from the producer side to the consumer side, and vice versa. Default value: true.

true

boolean

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 Direct VM endpoint is configured using URI syntax:

direct-vm:name

with the following path and query parameters:

81.2.1. Path Parameters (1 parameters):

NameDescriptionDefaultType

name

Required Name of direct-vm endpoint

 

String

81.2.2. Query Parameters (9 parameters):

NameDescriptionDefaultType

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/ERROR level and ignored.

false

boolean

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/ERROR level and ignored.

 

ExceptionHandler

exchangePattern (consumer)

Sets the default exchange pattern when creating an exchange.

 

ExchangePattern

block (producer)

If sending a message to a direct endpoint which has no active consumer, then we can tell the producer to block and wait for the consumer to become active.

true

boolean

failIfNoConsumers (producer)

Whether the producer should fail by throwing an exception, when sending to a Direct-VM endpoint with no active consumers.

false

boolean

timeout (producer)

The timeout value to use if block is enabled.

30000

long

headerFilterStrategy (producer)

Sets a HeaderFilterStrategy that will only be applied on producer endpoints (on both directions: request and response). Default value: none.

 

HeaderFilterStrategy

propagateProperties (advanced)

Whether to propagate or not properties from the producer side to the consumer side, and vice versa. Default value: true.

true

boolean

synchronous (advanced)

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

false

boolean

81.3. Samples

In the route below we use the direct component to link the two routes together:

from("activemq:queue:order.in")
    .to("bean:orderServer?method=validate")
    .to("direct-vm:processOrder");

And now in another CamelContext, such as another OSGi bundle

from("direct-vm:processOrder")
    .to("bean:orderService?method=process")
    .to("activemq:queue:order.out");

And the sample using spring DSL:

<route>
 <from uri="activemq:queue:order.in"/>
 <to uri="bean:orderService?method=validate"/>
 <to uri="direct-vm:processOrder"/>
</route>

<route>
 <from uri="direct-vm:processOrder"/>
 <to uri="bean:orderService?method=process"/>
 <to uri="activemq:queue:order.out"/>
</route>

81.4. See Also