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Basic Example

Overview

This document describes how to run the Basic example and provides details about what it does. For information on the business use case, please refer to: Use Case for Basic.

The Basic example illustrates the following:

The source code for the Basic example is located in the ServiceMix installation directory under the examples\basic\src\main\resources directory in the servicemix.xml file. It is recommended that you refer to the source code while reading this document.

There are several components in the servicemix.xmlfile. One component sets off a trigger to send messages to a source destination. Then those messages are consumed by another component and sent to a different output destination. A trace component displays the messages as they arrive.

Running the Basic Example

From a command shell, go to the Basic example directory:

cd [servicemix_install_dir]\examples\basic


Then type:

mvn jbi:embeddedServicemix



Handy Hint

This example starts an ActiveMQ JMS Broker, so be sure to stop any ServiceMix server already running.

Stopping the Basic Example

To terminate the Basic example type "CTRL-C" in the command shell in which it is running.

How it Works

The diagram below illustrates the flow of messages through the Basic components.

#cccBasic Example Message Flow Diagramsolid


 



Messages flow through the components as follows:

  1. The timer component sends a message to inputSender through the Normalized Message Router (NMR).
  2. inputSender converts the message (marshals it) into a JMS message, then uses the jmsTemplate bean to publish the message.
  3. jmsTemplate uses the jmsFactorybean to get a connection to the port associated with the JMS topic called "demo.org.servicemix.source." The message is published on the "demo.org.servicemix.source" topic.
  4. jencks (the JCA resource adapter) listens on port 61616 for messages.
  5. inputReceiver subscribes to the "demo.org.servicemix.source" topic via jencks and receives the JMS message.
  6. inputReceiver normalizes the JMS message and sends it to outputSender via the NMR.
  7. outputSender marshals the normalized message to a JMS message and uses jmsTemplate to publish the message on the "demo.org.servicemix.result" topic.
  8. jmsTemplate publishes it on the "demo.org.servicemix.result" topic using jmsFactory to get a connection to the result topic.
  9. jencks listens on port 61616 for messages.
  10. jmsTrace subscribes to the "demo.org.servicemix.result" topic and receives the JMS message via jencks.
  11. jmsTrace converts the JMS message into a normalized message and sends it to trace via the NMR.
  12. trace transforms the normalized message into a string and logs it to the console.

Every 5 seconds logging information is written to the console, followed by information from the trace component. Note, that the triggers' property values of "name", "My Example Job", "group", and "ServiceMix" are displayed along with a timestamp. Typical output looks like the following:

INFO TraceComponent - Exchange: InOnly[ id: ID:guillaumes-1927-1157464363171-19:11 status: Active role: provider service: {http://servicemix.apache.org/demo/}trace endpoint: trace in: <?xml version="1.0" encoding="UTF-8"?> <timer> <name>My Example Job</name> <group>ServiceMix</group> <fullname>ServiceMix.My Example Job</fullname> <description/> <fireTime>Tue Sep 05 15:53:39 CEST 2006</fireTime> </timer>

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 the following components: timer, inputSender, inputReceiver, outputSender, jmsTrace, and trace. During initialization, several singletons are instantiated: transactionManager, broker, jencks, jmsFactory, and jbi. After initialization, the components in the jbi container are activated, starting with the timer component.

timer

The timer component shows the use of the QuartzComponent class. Every 5 seconds, until the program is terminated, the timer component kicks off an instance of a SimpleTrigger, which is associated with an instance of JobDetail. The job has a property called "name" with a value of "My Example Job" and another property called "group" with a value of "ServiceMix." The resulting message is converted to a normalized message and routed through the NMR.

inputSender

This is a component inside the JBI container. It receives the normalized message (the message from the trigger), converts it to a JMS message, and publishes it to the topic called demo.org.servicemix.source. It uses the jmsTemplate(1) bean to handle the publish.

inputReceiver

This component uses jencks , the JCA container, to listen on port 61616 for a JMS message on the topic called "demo.org.servicemix.source." inputReceiver subscribes to the demo.org.servicemix.source topic. It takes the message, normalizes it, and routes it to outputSender via the NMR. This component combined with outputSender and supporting beans creates a JMS bridge between two topics.

outputSender

This component receives a normalized message from the NMR, marshals it into a JMS message using jmsTemplate, then publishes it on the ActiveMQ (JMS) topic called "demo.org.servicemix.result."

jmsTrace

This component uses jencks to subscribe to the "demo.org.servicemix.result" topic and get messages. It then marshals the message into a normalized message and routes it via the NMR to the trace component.

trace

Receives normalized messages from jmsTrace via the NMR. It transforms the normalized message into a string and logs it to the console.

jencks

The jencks bean defines a JCA container. The JCA container allows you to configure thread pool size, configure a transaction manager, and configure a resource adapter. In this example, the resource adapter is an ActiveMQ adapter, however, another JMS listener could be configured instead. This adapter listens on port 61616 for JMS messages.

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. jencksis configured to use the default transaction manager. 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 the jbi container.

jmsFactory

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

1. jmsTemplate: JmsTemplate is a Spring component which hides the low level details when sending JMS messages. For additional information see: JmsTemplate. jmsTemplate is not a component in the jbi container. It is used by inputSender and outputSender.

Use case

ServiceMix is an Enterprise Service Bus (ESB) that is based on the Java Business Integration (JBI) standard JSR 208. The JBI-based design specifies a standards-based pluggable architecture with a JVM-based runtime component called the Normalized Message Router (NMR). The Basic example demonstrates how applications communicate via the ServiceMix ESB, and the role that the NMR can play in that communication. Similar techniques could be used to plug any external 1 application or service into ServiceMix (e.g. SAP, Peoplesoft, spreadsheets, POJOs, Webservices and EJBs) and allow it to communicate with other external applications or components using ServiceMix itself.

A hypothetical business scenario, which extends the Basic Example, is that of a department store distributor. This distributor sells products from multiple wholesalers (suppliers) to various retailers (customers). The distributor presents a common interface for product ordering to each of its department store customers. However, the distributor must work with a different ordering interface for each wholesale suppliers for the products they are buying.

Using an ESB, the distributor has developed a number of components to receive department store orders and then dynamically route and transform these orders to the appropriate wholesaler. The order processing flow is described as follows:

  1. Using the distributor's web interface, a department store customer submits an order for multiple products. An HTTP request is sent to the OrderReceiver, an HTTP binding component (BC). 3
  2. The OrderReceiver sends the message to an OrderRouter service engine (SE) 4 component. This SE is responsible for parsing the order and deciding, based on the message content, which OrderTransformer should receive which part of the message (i.e., an order for a product).
  3. The OrderRouter publishes the orders to the appropriate message topics based on the message content. Specifically, the OrderRouter publishes the messages based on which wholesaler sells the item.
  4. The OrderTransformer is a service engine component, which modifies the message and puts it in a format which is readable by the wholesaler interface that will fulfill the order.
  5. Each OrderTransformer sends the modified message to the OrderProcessor.
  6. The OrderProcessor is a binding component that has two functions:
    a. It places an order to the appropriate wholesaler through the wholesaler's Webservice or proprietary interface.
    b. It also publishes a message about the order on a topic.
  7. The message on the topic is subsequently picked up by the BusinessMonitor component via the jmsTrace component.
  8. The BusinessMonitor component monitors the orders for quality assurance and business analytics, such as data mining.

The following diagram illustrates this:

#cccDepartment Store Distributor's Order Processing Systemsolid

  1. External means the application is outside of the ESB.
  2. Resource Adapter: a resource adapter provides connectivity between a specific external application and the ESB. In the Basic example the jencks container provides a JMS resource adapter.
  3. Binding Component (BC): a BC provides connectivity to applications that are external to the ESB.
  4. Service Engine (SE): a service engine provides business logic and transformation services to other components within the enterprise service bus.

Related Documentation

For more information on the following topics please see:

For a brief explanation of the XML tags in the servicemix.xml file, please see:

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