{section}
{column}

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.
The POJO can invoke any 'sub-service' during its processing by synchronous invocations using the {{jbiListener}} instance.
If the POJO service must reply with a message {{OUT}} or {{FAULT}}, according to the MEP, the method must build and set the message to the current exchange.
Then, the method musts return {{true}} to delegate the effective send back of the response or acknowledgment (according to the MEP) to the CDK.
The exceptions should be handled properly during the processing of the method, and set accordingly as error or fault to the exchange.
However, mishandled exceptions will be handled by the CDK as generic exceptions.

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)

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

<!-- 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}

{panel:title=Table of contents}{toc}{panel}
{panel:title=Contributors}{contributors:order=name|mode=list}{panel}
{column}
{section}