Chapter 19. Extensions

An extension is a module that extends the core capabilities of JBoss EAP.
You can extend SwitchYard functionality by creating extension modules for JBoss EAP. Use this feature to:
  • Support additional binding types through Camel components not included in the distribution.
  • Add data formats and other Camel libraries for use within Camel routing services.
  • Implement custom gateway bindings as Camel components.

19.1. Create SwitchYard Extension Module in JBoss EAP

Procedure 19.1. Create, Register and Build a SwitchYard Extension Module in JBoss EAP

  1. An extension is deployed in the modules folder of JBoss EAP.
    Extension modules are placed under the modules/system/layers/soa/org/ directory of your JBoss EAP installation. The jar files that make up the module are placed in the modules/system/layers/soa/org/product/subsystem/modulename/main directory. The module.xml file contains definition information. For example, in directory modules/system/layers/soa/org/apache/camel/saxon/main, the module.xml file looks like this:
    <?xml version="1.0" encoding="UTF-8"?>
     <module xmlns="urn:jboss:module:1.0" name="org.apache.camel.saxon">
    
        <resources>
            <resource-root path="camel-saxon-2.10.0.redhat-60024.jar"/>
            <resource-root path="saxon9he-9.3.0.11.jar"/>
        </resources>
    
        <dependencies>
            <module name="javax.api"/>
            <module name="org.slf4j"/>
            <module name="org.apache.camel.core"/>
        </dependencies>
    
    </module>
    The module.xml file contains the following information:
    • The module name. The module name is comprised of the directory names for the module underneath the EAP-Home/modules/system/layers/soa directory.
    • Resources required. Notice that the files mentioned in the <resources> section are in the same directory as the module.xml file.
    • Dependencies for the module.
  2. In order to make SwitchYard aware of the extension module, add the module name to the list of extensions defined in the SwitchYard subsystem in standalone.xml:
    <subsystem xmlns="urn:jboss:domain:switchyard:1.0">
      <modules>
        <module identifier="org.switchyard.component.bean" implClass="org.switchyard.component.bean.deploy.BeanComponent"/>
        <module identifier="org.switchyard.component.soap" implClass="org.switchyard.component.soap.deploy.SOAPComponent">
        <!-- snip -->
      </modules>
      <extensions>
        <extension identifier="org.apache.camel.mvel"/>
        <extension identifier="org.apache.camel.ognl"/>
        <extension identifier="org.apache.camel.jaxb"/>
        <extension identifier="org.apache.camel.soap"/>
        <extension identifier="org.apache.camel.saxon"/>
      </extensions>
    </subsystem>
  3. Build the application that will be using the module using the mvn clean install command. If there are problems running the JVM tests step locally, use the -DskipTests argument.
    Update the pom.xml file for the application. Add the module as a dependency and mark it as provided.
    <dependency>
        <groupId>org.apache.camel</groupId>
        <artifactId>camel-saxon</artifactId>
        <version>2.10.0.redhat-60024</version>
        <scope>provided</scope>
    </dependency>
  4. If the module is created from a jar not supplied with JBoss Fuse Service Works, you must ensure that a jboss-deployment-structure.xml file exists in the application-name/src/main/resources/META-INF folder of the application that will run it. The jboss-deployment-structure.xml file contains information in the following format:
    <?xml version="1.0" encoding="UTF-8"?>  
    <jboss-deployment-structure>  
        <deployment>  
            <dependencies>  
                <module name="org.apache.camel.saxon" services="import" export="true">  
                    <imports>  
                        <include path="META-INF/services/org/apache/camel/component" />  
                        <include path="META-INF/services/org/apache/camel/language" />  
                    </imports>  
                    <exports>  
                        <include path="META-INF/services/org/apache/camel/component" />  
                        <include path="META-INF/services/org/apache/camel/language" />  
                    </exports>  
                </module>  
            </dependencies>  
        </deployment>  
    </jboss-deployment-structure>
    The module name must be the same as the module name defined in step 1 with the same naming rules.
For an example of an extension module and an application, see https://access.redhat.com/solutions/653823.

19.2. Extension Types and Usage

How you use an extension in your application depends on the type of extension.

Table 19.1. Extensions

Type Usage
Camel DataFormat Once a data format is packaged as a module and added as an extension to the SwitchYard subsystem, no further configuration is required in your application. You can refer to the data format directly in your route as if it was packaged directly within your application.
Camel Gateway Components If the extension is to be used as a gateway binding for services or references, then use the Camel URI binding in your application to configure the endpoint details.