components/camel-ref/src/main/docs/ref-component.adoc

[[ref-component]]
== Ref Component

*Available as of Camel version 1.2*

The *ref:* component is used for lookup of existing endpoints bound in
the Registry.

=== URI format

[source]
----
ref:someName[?options]
----

Where *someName* is the name of an endpoint in the
Registry (usually, but not always, the Spring
registry). If you are using the Spring registry, `someName` would be the
bean ID of an endpoint in the Spring registry.

=== Ref Options

// component options: START
The Ref component supports 2 options, which are listed below.



[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *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
| *basicPropertyBinding* (advanced) | Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities | false | boolean
|===
// component options: END


// endpoint options: START
The Ref endpoint is configured using URI syntax:

----
ref:name
----

with the following path and query parameters:

==== Path Parameters (1 parameters):


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|===
| Name | Description | Default | Type
| *name* | *Required* Name of endpoint to lookup in the registry. |  | String
|===


==== Query Parameters (5 parameters):


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|===
| Name | Description | Default | Type
| *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
| *exceptionHandler* (consumer) | 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) | Sets the exchange pattern when the consumer creates an exchange. |  | ExchangePattern
| *basicPropertyBinding* (advanced) | Whether the endpoint should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities | false | boolean
| *synchronous* (advanced) | Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported). | false | boolean
|===
// endpoint options: END

// spring-boot-auto-configure options: START
=== Spring Boot Auto-Configuration

When using Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

[source,xml]
----
<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-ref-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>
----


The component supports 3 options, which are listed below.



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|===
| Name | Description | Default | Type
| *camel.component.ref.basic-property-binding* | Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities | false | Boolean
| *camel.component.ref.enabled* | Whether to enable auto configuration of the ref component. This is enabled by default. |  | Boolean
| *camel.component.ref.resolve-property-placeholders* | Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders. | true | Boolean
|===
// spring-boot-auto-configure options: END

=== Runtime lookup

This component can be used when you need dynamic discovery of endpoints
in the Registry where you can compute the URI at
runtime. Then you can look up the endpoint using the following code:

[source,java]
----
// lookup the endpoint
String myEndpointRef = "bigspenderOrder";
Endpoint endpoint = context.getEndpoint("ref:" + myEndpointRef);

Producer producer = endpoint.createProducer();
Exchange exchange = producer.createExchange();
exchange.getIn().setBody(payloadToSend);
// send the exchange
producer.process(exchange);
----

And you could have a list of endpoints defined in the
Registry such as:

[source,xml]
----
<camelContext id="camel" xmlns="http://activemq.apache.org/camel/schema/spring">
    <endpoint id="normalOrder" uri="activemq:order.slow"/>
    <endpoint id="bigspenderOrder" uri="activemq:order.high"/>
</camelContext>
----

=== Sample

In the sample below we use the `ref:` in the URI to reference the
endpoint with the spring ID, `endpoint2`:

You could, of course, have used the `ref` attribute instead:

[source,xml]
----
<to uri="ref:endpoint2"/>
----

Which is the more common way to write it.