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Overview of the ServiceMix 1.x WSIF Example

This document describes the components that integrate with the Apache Web Service Invocation Framework (WSIF) to perform web service invocations using a number of different implementation protocols such as Axis, local Java, EJB, JMS, JCA and CCI.

The WSIF example illustrates the following:

  • an example of declarative programming
  • how to enable a service to be exposed over a JMS queue through WSIF

The following example shows how to bind a WSDL file for a web service, which is adorned with WSIF additional metadata to configure the service implementation. 

<component id="checkAvailability" service="foo:checkAvailability" class="org.servicemix.components.wsif.WSIFBinding">
  <property name="definitionResource" value="classpath:org/servicemix/components/wsif/service.wsdl"/>
</component>


How it Works

The diagram below illustrates the logical flow of the program through the WSIF components:



BPEL Logical Flow Diagram



The logical flow of the program is:

  1. A user opens a web browser and access a web form with a "zipcode" input field and a submit button. The submit button sends the form and the zipcode typed in by the user to a Servicemix HTTP binding component.
  2. The HTTP binding component creates an InOut exchange message through the client API. The message is sent through the NMR to the checkAvailability component
  3. The checkAvailability component sends the request to the JMS queue.
  4. The webservice is implemented with a message driven EJB (MDB), who's "onMessage" method is listening for messages on the queue
  5. The MDB, processes the request and sends back a response to the checkAvailability component through a temporary queue.
  6. The checkAvailability component receives the response from the queue.
  7. The checkAvailability component responds to the HTTP client.
  8. The HTTP client sends the result back to the web form. The value of the result property is displayed and let's the user know whether or not DSL is available at the zipcode.

Details

The following table provides more details about the function of each component and bean in the servicemix.xml file:

Component or Bean ID

Description

jbi

jbi is the "id" of the JBI container and provides the basic infrastructure services for myComponent. During initialization, several singletons are instantiated: transactionManager, broker, jmsFactory, and jbi. Also, take note of the properties installationDirPath and deploymentDirPath defined in servicemix.xml. ServiceMix automatically installs components found in the folder specified in the installationDirPath property. It automatically deploys component-specific artifacts found in the folder specified in the deploymentDirPath property.

JMSClient

This Java standalone program, through the ActiveMQConnectionFactory, connects to topic "demo.org.servicemix.source." It then creates a text message from the file message.soap and publishes it to the topic "demo.org.servicemix.source," then requests and waits for a response. It eventually prints the response to the console.

myComponent

This JMS service component subscribes to the "demo.org.servicemix.source" topic via its defaultDestinationName property specified in the servicemix.xml configuration file. Through its template property, it uses jmsFactory to listen on port 61616 via ActiveMQConnectionFactory. It is implemented by the JmsServiceComponent that has an onMessage() method which is called by ActiveMQ when a message arrives on the topic. This method creates a normalized message, which is sent over the ServiceMix bus to the PxeBpelEngine as specified on its destinationService property.

jndi

This bean loads up database and transaction manager resources, which will be used by the other components in the system. More importantly, the JNDI context must be configured so that PXE can be deployed.

Pxe-install.jar

This jarfile is located in the examples\bpel\install directory. It contains many files, which in turn contain the classes that implement the PXE BPEL engine. It also has a jbi.xml file, which is used by ServiceMix to install the PXE BPEL engine as a ServiceMix service-engine component. Note, that in this file the component type is "service-engine" and the component name is PxeBpelEngine. When processes are deployed to the PXE engine (see next row with AsyncProcess-sa.jar), it exposes them as services on the JBI, which can be referenced by other components as destinationService(s), with destinationEnpoint(s) - see the servicemix.xml file.

AsyncProcess-sa.jar

This jarfile is located in the examples\bpel\deploy directory. It contains a jbi.xml file, which references the PxeBpelEngine. This ties the processes to the PXE engine described in the previous section. The jbi.xml file also references the AsyncProcess-su.zip file, which is also contained in the AsycnProcess-sa.jar file. This zipfile contains other configuration files and WSDL files, i.e., pxe-system.xml and resource_X.stream, which describe the services deployed on the PXE engine.

broker

The broker bean uses the activemq.xml file to configure the message broker, which handles the JMS messages for the components that require JMS messaging services.

transactionManager

This bean is configured to be the default transaction manager for the jbi container. This transaction manager provides transactional services between the resource adapter (in this case the ActiveMQ resource adapter provided by the jencks JCA container) and components in the jbi container.

jmsFactory

This bean listens on port 61616 and provides a pooled ActiveMQ connection.

Related Documentation

For more information on the following topics please see:

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