Apache ServiceMix, the Agile Open Source ESB -- BPEL example

Overview of the ServiceMix 1.x BPEL Example

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

The BPEL example illustrates the following:

an example of declarative programming
how to perform BPEL integration with ServiceMix
how to use JmsTemplate for publishing and subscribing to ActiveMQ topics

The XML code for the BPEL example is located in the ServiceMix installation directory under the examples\bpel directory in the servicemix.xml file. It is recommended that you refer to the servicemix.xml file while reading this document.

This example has a client application, JMSClient, which sends a SOAP message to a ServiceMix binding component called myComponent. myComponent forwards the request to the PXE BPEL engine and waits for a response. In other words, JMSClient places a book order and myComponent receives the order and then sends it to the Webservice that takes orders. The client, JMSClient, and the binding component, myComponent, communicate via JMS; this communication is external to the ServiceMix JBI. myComponent and the PXE BPEL service engine communicate internally over the Normalized Message Router (NMR).

Prerequisites to Run the BPEL Example

The following must be installed to run this example:

Java Standard Edition 5.0
Ant - http://ant.apache.org
PXE - We support WS-BPEL via the PXE BPEL Engine from FiveSight.

Warning
NOTE: ServiceMix works on any Java SE 1.4 or later environment; however to use PXE a Java SE 5 or later platform is required. Before running this example, use Java 1.5 to start up ServiceMix.

Running the BPEL Example

Before running this example, the following setup must be done. PXE has a JBI component and deployment unit, which can be auto-deployed in any JBI compliant container, in this case ServiceMix. To use PXE with ServiceMix, the PXE deployment unit must be placed in the install directory so it will be auto-deployed in ServiceMix. NOTE: The PXE deployment unit has already been placed into the install directory for you - take a look at the servicemix_install_dir\examples\bpel\install directory to see the PXE jar file.

Perform the following steps to run the BPEL example:

From a command shell, go to the BPEL example directory:
```
cd [servicemix_install_dir]\examples\bpel
```
where servicemix_install_dir is the directory in which ServiceMix was installed.

Then type:

[servicemix_install_dir]\bin\servicemix servicemix.xml

OR

..\..\bin\servicemix servicemix.xml

To trigger the BPEL business process, send it some messages. To do this, compile and run a simple JMS client. The client is built and run from source code using Ant. Execute Ant from the BPEL directory: servicemix_install_dir\examples\bpel. To run the JMS client type:
```
ant
```
Ant will compile and run the simple JMS client, JMSClient, which performs a JMS based request-response into the ServiceMix container before returning the results to the console.

Handy Hint
Add $SERVICEMIX_HOME\bin directory to $PATH variable to simplify execution of the example.

Stopping the BPEL Example

To terminate the BPEL example type "CTRL-C" in the command shell in which it is running and answer "y" to the "Terminate batch job (y/n)?" question.

How it Works

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

BPEL Logical Flow Diagram

The logical flow of the program is:

The JMSClient, through ActiveMQConnectionFactory, connects to the topic named "demo.org.servicemix.source" and sends a text message containing the message.soap file.
myComponent, being a subscriber of the topic "demo.org.servicemix.source," receives the message.
The myComponent implementation class, JmsServiceComponent, sends the message over the ServiceMix bus to the PxeBpelEngine by executing its onMessage() method. The destinationService property defines the destination of the message. NOTE: the destinationService property is found in the servicemix.xml file.
PxeBpelEngine sends a response back to myComponent through the ServiceMix bus, the NMR.
myComponent uses the jmsTemplate bean to publish the message.
jmsTemplate uses the jmsFactory bean 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.
JMSClient, being a subscriber of topic "demo.org.servicemix.source," receives the message.
The response is printed on the console.

Typical output looks like the following:

ServiceMix ESB: 1.0

Loading ServiceMix from file: servicemix.xml
[INFO] XmlBeanDefinitionReader - -Loading XML bean definitions from file C:\exist\servicemix\servicemix-1.0.1\examples\bpel\servicemix.xml]
[INFO] CollectionFactory - -JDK 1.4+ collections available
[INFO] CollectionFactory - -Commons Collections 3.x available
[INFO] FileSystemXmlApplicationContext - -Bean factory for application context
[org.springframework.context.support.FileSystemXmlApplicationContext;hashCode=110
2920]: org.springframework.beans.factory.support.DefaultListableBeanFactory defining beans
[jndi,broker,transactionManager,jmsFactory,jbi];
 root of BeanFactory hierarchy[INFO] FileSystemXmlApplicationContext - -5 beans defined in application context
 [org.springframework.context.support.FileSystemXmlApplicationContext;hashCode=1102920]
[INFO] FileSystemXmlApplicationContext - -Unable to locate MessageSource with name 'messageSource': using default
[org.springframework.context.support.DelegatingMessageSource@18e2b22]
[INFO] FileSystemXmlApplicationContext - -Unable to locate ApplicationEventMulticaster with name 'applicationEventMulticaster':
using default [org.springframework.context.event.SimpleApplicationEventMulticaster@13caecd]
[INFO] DefaultListableBeanFactory - -Pre-instantiating singletons in factory
 [org.springframework.beans.factory.support.DefaultListableBeanFactory
defining beans [jndi,broker,transactionManager,jmsFactory,jbi]; root of BeanFactory hierarchy]
[INFO] DefaultListableBeanFactory - -Creating shared instance of singleton bean'jndi'
[INFO] DefaultListableBeanFactory - -Creating shared instance of singleton bean 'broker'
[INFO] SpringBrokerContainerFactory - -Loading ActiveMQ broker from configuration: class path resource [activemq.xml]
[INFO] ActiveMQBeanDefinitionReader - -Loading XML bean definitions from class path resource [activemq.xml]
[INFO] ActiveMQBeanFactory - -Creating shared instance of singleton bean 'broker'
[INFO] ActiveMQBeanFactory - -Creating shared instance of singleton bean 'memoryManager'
[INFO] ActiveMQBeanFactory - -Creating shared instance of singleton bean 'derby-ds'
[INFO] ActiveMQBeanFactory - -Creating shared instance of singleton bean 'mysql-ds'
[INFO] BrokerContainerImpl - -ActiveMQ 3.1-M6 JMS Message Broker (ID:el2tong-1095-1129854563062-0:0) is starting
[INFO] BrokerContainerImpl - -For help or more information please see: http://www.logicblaze.com
[INFO] JDBCPersistenceAdapter - -Database driver recognized: [apache_derby_embedded_jdbc_driver]
[INFO] DefaultJDBCAdapter - -Could not create JDBC tables; they could already exist. Failure was:
CREATE TABLE ACTIVEMQ_MSGS(ID INTEGER NOT NULL, CONTAINER VARCHAR(250), MSGID VARCHAR(250), MSG BLOB, PRIMARY KEY ( ID ) )
Message: Table/View 'ACTIVEMQ_MSGS' already exists in Schema 'APP'. SQLState: X0Y32 Vendor code: 20000
[INFO] DefaultJDBCAdapter - -Could not create JDBC tables; they could already exist. Failure was:
CREATE TABLE ACTIVEMQ_TXS(XID VARCHAR(250) NOT NULL, PRIMARY KEY ( XID )) Message: Table/View 'ACTIVEMQ_TXS' already exists in Schema 'APP'. SQLState: X0Y32 Vendor code: 20000
[INFO] DefaultJDBCAdapter - -Could not create JDBC tables; they could already exist. Failure was:
CREATE TABLE ACTIVEMQ_ACKS(SUB VARCHAR(250) NOT NULL, CONTAINER VARCHAR(250) NOT NULL, LAST_ACKED_ID INTEGER, SE_ID INTEGER,
SE_CLIENT_ID VARCHAR(250), SE_CONSUMER_NAME VARCHAR(250), SE_SELECTOR VARCHAR(250), PRIMARY KEY (
 SUB, CONTAINER )) Message: Table/View 'ACTIVEMQ_ACKS' already exists in Schema 'APP'. SQLState: X0Y32 Vendor code: 20000
[INFO] DefaultJDBCAdapter - -Could not create JDBC tables; they could already exist. Failure was:
ALTER TABLE ACTIVEMQ_MSGS ADD EXPIRATION BIGINT Message: Column 'EXPIRATION' already exists in Table/View 'APP.ACTIVEMQ_MSGS'. SQLState: X0Y32 Vendor code: 20000
[INFO] JournalPersistenceAdapter - -Opening journal.
[INFO] JournalPersistenceAdapter - -Opened journal: Active Journal: using 2 x 20.0 Megs at: ..\var\journal
[INFO] JournalPersistenceAdapter - -Journal Recovery Started.
[INFO] JournalPersistenceAdapter - -Journal Recovered: 0 message(s) in transactions recovered.
[INFO] TcpTransportServerChannel - -Listening for connections at: tcp://el2tong:61616
[INFO] BrokerConnectorImpl - -ActiveMQ connector started: TcpTransportServerChannel@tcp://el2tong:61616
[INFO] BrokerContainerImpl - -ActiveMQ JMS Message Broker (ID:el2tong-1095-1129854563062-0:0) has started
[INFO] DefaultListableBeanFactory - -Creating shared instance of singleton bean 'transactionManager'
[INFO] DefaultListableBeanFactory - -Creating shared instance of singleton bean 'jmsFactory'
[INFO] DefaultListableBeanFactory - -Creating shared instance of singleton bean 'jbi'
[INFO] ActiveMQConnection - -channel status changed: Channel: TcpTransportChannel: Socket[addr=localhost/127.0.0.1,port=61616,localport=1096] has connected
[INFO] BrokerContainerImpl - -Adding new client: ID:el2tong-1095-1129854563062-5:0 on transport: TcpTransportChannel: Socket[addr=/127.0.0.1,port=1096,localport=61616]
[INFO] JBIContainer - -ServiceMix JBI Container (http://servicemix.org/) name: defaultJBI running version: ServiceMix.
[INFO] JBIContainer - -Activating component for: [container=defaultJBI,name=myComponent,id=myComponent]
 with service: {uri:fivesight.com/examples/AsyncProcessJBI}JmsService component: org.servicemix.components.jms.JmsServiceComponent@1b82d69
[INFO] ComponentContextImpl - -Component: myComponent activated endpoint: {uri:fivesight.com/examples/AsyncProcessJBI}JmsService : myComponent

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.

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