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Chapter 91. EJB Component

Available as of Camel version 2.4

The ejb: component binds EJBs to Camel message exchanges.

Maven users will need to add the following dependency to their pom.xml for this component: 

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-ejb</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>
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91.1. URI format
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ejb:ejbName[?options]
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Where ejbName can be any string which is used to look up the EJB in the Application Server JNDI Registry

91.2. Options
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The EJB component supports 3 options which are listed below.

Expand
NameDescriptionDefaultType

context (producer)

The Context to use for looking up the EJBs

 

Context

properties (producer)

Properties for creating javax.naming.Context if a context has not been configured.

 

Properties

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 EJB endpoint is configured using URI syntax: 

ejb:beanName
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with the following path and query parameters:

91.2.1. Path Parameters (1 parameters):
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Expand
NameDescriptionDefaultType

beanName

Required Sets the name of the bean to invoke

 

String

91.2.2. Query Parameters (5 parameters):
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Expand
NameDescriptionDefaultType

method (producer)

Sets the name of the method to invoke on the bean

 

String

cache (advanced)

If enabled, Camel will cache the result of the first Registry look-up. Cache can be enabled if the bean in the Registry is defined as a singleton scope.

false

boolean

multiParameterArray (advanced)

Deprecated How to treat the parameters which are passed from the message body.true means the message body should be an array of parameters.. Deprecation note: This option is used internally by Camel, and is not intended for end users to use. Deprecation note: This option is used internally by Camel, and is not intended for end users to use.

false

boolean

parameters (advanced)

Used for configuring additional properties on the bean

 

Map

synchronous (advanced)

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

false

boolean

91.3. Bean Binding
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How bean methods to be invoked are chosen (if they are not specified explicitly through the method parameter) and how parameter values are constructed from the Message are all defined by the Bean Binding mechanism which is used throughout all of the various Bean Integration mechanisms in Camel.

91.4. Examples
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In the following examples we use the Greater EJB which is defined as follows:

GreaterLocal.java 

public interface GreaterLocal {

    String hello(String name);

    String bye(String name);

}
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And the implementation

GreaterImpl.java 

@Stateless
public class GreaterImpl implements GreaterLocal {

    public String hello(String name) {
        return "Hello " + name;
    }

    public String bye(String name) {
        return "Bye " + name;
    }

}
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91.4.1. Using Java DSL
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In this example we want to invoke the hello method on the EJB. Since this example is based on an unit test using Apache OpenEJB we have to set a JndiContext on the EJB component with the OpenEJB settings. 

@Override
protected CamelContext createCamelContext() throws Exception {
    CamelContext answer = new DefaultCamelContext();

    // enlist EJB component using the JndiContext
    EjbComponent ejb = answer.getComponent("ejb", EjbComponent.class);
    ejb.setContext(createEjbContext());

    return answer;
}

private static Context createEjbContext() throws NamingException {
    // here we need to define our context factory to use OpenEJB for our testing
    Properties properties = new Properties();
    properties.setProperty(Context.INITIAL_CONTEXT_FACTORY, "org.apache.openejb.client.LocalInitialContextFactory");

    return new InitialContext(properties);
}
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Then we are ready to use the EJB in the Camel route: 

from("direct:start")
    // invoke the greeter EJB using the local interface and invoke the hello method
    .to("ejb:GreaterImplLocal?method=hello")
    .to("mock:result");
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In a real application server

In a real application server you most likely do not have to setup a JndiContext on the EJB component as it will create a default JndiContext on the same JVM as the application server, which usually allows it to access the JNDI registry and lookup the EJBs. However if you need to access a application server on a remote JVM or the likes, you have to prepare the properties beforehand.

91.4.2. Using Spring XML
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And this is the same example using Spring XML instead:

Again since this is based on an unit test we need to setup the EJB component: 

<!-- setup Camel EJB component -->
<bean id="ejb" class="org.apache.camel.component.ejb.EjbComponent">
    <property name="properties" ref="jndiProperties"/>
</bean>

<!-- use OpenEJB context factory -->
<p:properties id="jndiProperties">
    <prop key="java.naming.factory.initial">org.apache.openejb.client.LocalInitialContextFactory</prop>
</p:properties>
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Before we are ready to use EJB in the Camel routes: 

<camelContext xmlns="http://camel.apache.org/schema/spring">
    <route>
        <from uri="direct:start"/>
        <to uri="ejb:GreaterImplLocal?method=hello"/>
        <to uri="mock:result"/>
    </route>
</camelContext>
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91.5. See Also
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  • Configuring Camel
  • Component
  • Endpoint
  • Getting Started
  • Bean
  • Bean Binding
  • Bean Integration
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