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h1. Exposing a Java class as a POJO service (Provides mode)

h2. Usage

The POJO that you want to develop must follow certain constraints :
* no specific interface implementation is required.
* if a {{public setComponentContext(ComponentContext context)}} setter method is defined, the component set its {{ComponentContext}} instance with this method at the initialization of the Service Unit.
* if a {{public setDeliveryChannel(DeliveryChannel channel)}} setter method is defined, the component set its {{DeliveryChannel}} instance with this method at the initialization of the Service Unit.
* if a {{public setJBIListener(AbstractJBIListener jbiListener)}} setter method is defined, the component set its {{JBIListener}} instance with this method at the initialization of the Service Unit.
* if a {{public setLogger(Logger logger)}} setter method is defined, the component set its {{Logger instance}} with this method at the initialization of the Service Unit.
* if a {{public void init()}} method is defined, the component invoke it at the initialization of the Service Unit.
* a {{public boolean onExchange(Exchange exchange)}} MUST be provided.
* an {{public boolean onAsyncExchange(Exchange exchange, AsyncContext asyncContext)}} CAN be provided, optionally.
* all methods can throw exceptions.


h3. Process a service in the synchronous way

A sample class following the above rules for processing service in the synchronous way:
{code:java}
package test;
import java.util.logging.Level;
[...]
import org.ow2.petals.component.framework.listener.AbstractJBIListener;

public class SamplePojoService {
AbstractJBIListener jbiListener;
Logger logger;
ComponentContext ctx;

public void setJBIListener(AbstractJBIListener jbiListener) {
this.jbiListener = jbiListener;
}
public void setComponentContext(ComponentContext ctx) {
this.ctx = ctx;
}
public void setLogger(Logger logger) {
this.logger = logger;
}

public boolean onExchange(Exchange exchange)
throws MessagingException {
[...]
jbiListener.sendSync(anotherExchange);
[...]
return true;
}

public void init() {
logger.log(Level.INFO, "Sample Pojo inits.");
}
}
{code}

The method {{onExchange(Exchange exchange)}} is invoked when an exchange is received from the component that is addressed to the current POJO endpoint.
The POJO must process the service in that method.

h3. Process a service in the asynchronous way


A sample class following the above rules for processing service in the asynchronous way:
{code:java}
package test;
import java.util.logging.Level;
[...]
import org.ow2.petals.component.framework.listener.AbstractJBIListener;

public class SamplePojoService {
AbstractJBIListener jbiListener;
Logger logger;
ComponentContext ctx;

public void setJBIListener(AbstractJBIListener jbiListener) {
this.jbiListener = jbiListener;
}
public void setComponentContext(ComponentContext ctx) {
this.ctx = ctx;
}
public void setLogger(Logger logger) {
this.logger = logger;
}

public boolean onExchange(Exchange exchange)
throws MessagingException {
[...]
MyAsyncContext myAsyncContext = new MyAsyncContext(...);
[...]
jbiListener.sendASync(anotherExchange, myAsyncContext);
[...]
return false;
}

public boolean onAsyncExchange(Exchange subExchange, AsyncContext asyncContext)
throws MessagingException {
[...]
Exchange originalExchange = asyncContext.getOriginalExchange();
[...]
jbiListener.send(originalExchange);
[...]
return true;
}


public void init() {
logger.log(Level.INFO, "Sample Pojo Async inits.");
}
}
{code}
Processing a service in asynchronous way is the best approach when targeting performance, but it's more tedious to develop, and demands an average level in Petals development.
Basically, all is in the data that permit to correlate asynchronous sent exchange and their asynchronous response.
The original exchange is the received by the component and the process of the service start in the {{onExchange(Exchange exchange)}} method.
The method create an asynchronous context, to set the data.

h2. Service Configuration

{code:xml}
<?xml version="1.0" encoding="UTF-8"?>
<!-- JBI descriptor for PEtALS' "petals-se-pojo" (POJO), version 2.0 -->
<jbi:jbi version="1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:jbi="http://java.sun.com/xml/ns/jbi"
xmlns:pojo="http://petals.ow2.org/components/pojo/version-2.0"
xmlns:petalsCDK="http://petals.ow2.org/components/extensions/version-4.0"
xmlns:generatedNs="http://POJO/test">
<!-- Import a Service into PEtALS or Expose a PEtALS Service => use a BC. -->
<jbi:services binding-component="false">
<!-- Import a Service into PEtALS => provides a Service. -->
<jbi:provides
interface-name="generatedNs:POJO"
service-name="generatedNs:POJOService"
endpoint-name="POJOServiceEndpoint">
<!-- CDK specific elements -->
<petalsCDK:wsdl xsi:nil="true" />
<!-- Component specific elements -->
<pojo:class-name>test.SamplePojoService</pojo:class-name>
</jbi:provides>
</jbi:services>
</jbi:jbi>
{code}

{include:0 CDK SU Provide Configuration}

{table-plus}

{include:0 CDK SU Interceptor configuration}

h3. Service Unit content

The POJO class(es) and their depending libraries must be set as JAR(s) file(s) at the root directory of the POJO Service
Unit package.

The Service Unit must contain the following elements, packaged in an ZIP archive:
* The META-INF/jbi.xml descriptor file, has described above.
* At least one jar containing the POJO class to expose
{code}
service-unit.zip
+ META-INF
- jbi.xml (as defined above)
- mypojoclasses.jar
{code}

h1. Component Configuration

{include:0 CDK Component Configuration Table 2.1}

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