Wire Tap

Wire Tap from the EIP patterns allows you to route messages to a separate location while they are being forwarded to the ultimate destination.

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Options

The Wire Tap eip supports 1 options, which are listed below.

Name Description Default Type

note

The note for this node.

String

description

The description for this node.

String

disabled

Whether to disable this EIP from the route during build time. Once an EIP has been disabled then it cannot be enabled later at runtime.

false

Boolean

copy

Whether to use a copy of the original exchange.

true

Boolean

dynamicUri

Whether the uri is dynamic or static. If dynamic then the simple language is used to evaluate a dynamic uri to use as the wire-tap destination, for each incoming message.

true

Boolean

onPrepare

Uses a processor when preparing the exchange to be sent. This can be used to deep-clone messages, or any custom logic needed before the exchange is sent.

Processor

executorService

Uses a custom thread pool for sending tapped exchanges.

ExecutorService

uri

Required The uri of the endpoint to send to. The uri can be dynamic computed using the simple language.

String

variableSend

To use a variable as the source for the message body to send. This makes it handy to use variables for user data and to easily control what data to use for sending and receiving.

String

variableReceive

To use a variable to store the received message body (only body, not headers). This makes it handy to use variables for user data and to easily control what data to use for sending and receiving.

String

cacheSize

Sets the maximum size used by the ProducerCache which is used to cache and reuse producers when uris are reused. Use 0 for default cache size, or -1 to turn cache off.

Integer

ignoreInvalidEndpoint

Whether to ignore invalid endpoint URIs and skip sending the message.

false

Boolean

allowOptimisedComponents

Whether to allow components to optimise toD if they are SendDynamicAware.

true

Boolean

autoStartComponents

Whether to auto startup components when toD is starting up.

true

Boolean

Exchange properties

The Wire Tap eip supports 1 exchange properties, which are listed below.

The exchange properties are set on the Exchange by the EIP, unless otherwise specified in the description. This means those properties are available after this EIP has completed processing the Exchange.

Name Description Default Type

CamelToEndpoint

Endpoint URI where this Exchange is being sent to.

String

Wire Tap

Camel’s Wire Tap will copy the original Exchange and set its Exchange Pattern to InOnly, as we want the tapped Exchange to be sent in a fire and forget style. The tapped Exchange is then sent in a separate thread, so it can run in parallel with the original. Beware that only the Exchange is copied - Wire Tap won’t do a deep clone (unless you specify a custom processor via onPrepare which does that). So all copies could share objects from the original Exchange.

Using Wire Tap

In the example below, the exchange is wire tapped to the direct:tap route. This route delays message 1 second before continuing. This is because it allows you to see that the tapped message is routed independently of the original route, so that you would see log:result happens before log:tap

  • Java

  • XML

  • YAML

from("direct:start")
    .to("log:foo")
    .wireTap("direct:tap")
    .to("log:result");

from("direct:tap")
    .delay(1000).setBody().constant("Tapped")
    .to("log:tap");
<routes>

  <route>
    <from uri="direct:start"/>
    <wireTap uri="direct:tap"/>
    <to uri="log:result"/>
  </route>

  <route>
    <from uri="direct:tap"/>
    <to uri="log:log"/>
  </route>

</routes>
- route:
    from:
      uri: direct:start
      steps:
        - to:
            uri: log:foo
        - wireTap:
            uri: direct:tap
        - to:
            uri: log:result
- route:
    from:
      uri: direct:tap
      steps:
        - delay:
            expression:
              constant:
                expression: 1000
        - setBody:
            expression:
              constant:
                expression: Tapped
        - to:
            uri: log:tap

Wire tapping with dynamic URIs

For example, to wire tap to a dynamic URI, then the URI uses the Simple language that allows to construct dynamic URIs.

For example, to wire tap to a JMS queue where the header ID is part of the queue name:

  • Java

  • XML

  • YAML

from("direct:start")
    .wireTap("jms:queue:backup-${header.id}")
    .to("bean:doSomething");
<route>
  <from uri="direct:start"/>
  <wireTap uri="jms:queue:backup-${header.id}"/>
  <to uri="bean:doSomething"/>
</route>
- route:
    from:
      uri: direct:start
      steps:
        - wireTap:
            uri: "jms:queue:backup-${header.id}"
        - to:
            uri: bean:doSomething

WireTap Thread Pools

The WireTap uses a thread pool to process the tapped messages. This thread pool will by default use the settings detailed in the Threading Model.

In particular, when the pool is exhausted (with all threads used), further wiretaps will be executed synchronously by the calling thread. To remedy this, you can configure an explicit thread pool on the Wire Tap having either a different rejection policy, a larger worker queue, or more worker threads.

Wire tapping Streaming based messages

If you Wire Tap a stream message body, then you should consider enabling Stream caching to ensure the message body can be read at each endpoint.

See more details at Stream caching.

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