THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
Writing the bean class
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We now have to
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write the bean class |
Creating the bean class
Preparing an Eclipse project
In order to ease the development we will now make use of Mavens ability to create Eclipse projects. From the http-handler-su main folder run the following comand:
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... [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESSFUL [INFO] ------------------------------------------------------------------------ [INFO] Total time: 5 seconds [INFO] Finished at: Wed Nov 28 12:21:12 CET 2007 [INFO] Final Memory: 14M/78M [INFO] ------------------------------------------------------------------------ |
Importing the project into Eclipse
Now it's time to start up Eclipse workbench. Choose File > Import > Existing Projects into Workspace.
Then select the projects root directory and press OK. A project named http-handler-su should now be visible inside the Import window's projects list. Make sure it's checkbox is selected and press finish.
The project should now appear in your Package Explorer view.
Be sure you have specified the M2_REPO classpath variable to point on your local Maven repository which is located in your home folder.
For example: /home/lhe/.m2/repository
If you don't know how to specify this variable refer to the Eclipse documentation or Google it.
Create the bean class file
Next thing to do is creation the bean class. For this select the src/main/java folder in your project. Now delete everything inside this folder.
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*
This method is responsible for handling incoming messages.
Handling incoming messages
We assume (and do not further check) that each incoming message exchange is of type InOut MEP. Feel free to improve this and check for the correct Message Exchange Pattern.
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This is of course a stupid example, so just imagine you convert this file into another format and send the result back.
You can do such a logic if you want. For this you can refer for example to OpenOffice running in headless mode in combination with the JODConverter of "Arts of Solving". This will enable you to convert for example a .odt document into a .pdf document. But this is really out of scope now.
The finished class
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package org.apache.servicemix.jbi;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.Set;
import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.annotation.Resource;
import javax.jbi.messaging.DeliveryChannel;
import javax.jbi.messaging.ExchangeStatus;
import javax.jbi.messaging.MessageExchange;
import javax.jbi.messaging.MessagingException;
import javax.jbi.messaging.NormalizedMessage;
import javax.jbi.messaging.MessageExchange.Role;
import org.apache.log4j.Logger;
import org.apache.servicemix.MessageExchangeListener;
import org.apache.servicemix.jbi.jaxp.StringSource;
import org.apache.servicemix.jbi.util.StreamDataSource;
public class HandlerBean implements MessageExchangeListener
{
private static final Logger logger = Logger.getLogger(HandlerBean.class);
@Resource
private DeliveryChannel channel;
/*
* (non-Javadoc)
* @see org.apache.servicemix.MessageExchangeListener#onMessageExchange(javax.jbi.messaging.MessageExchange)
*/
public void onMessageExchange(MessageExchange exchange) throws MessagingException
{
if (exchange == null)
{
return;
}
// The component acts as a consumer, this means this exchange is received because
// we sent it to another component. As it is active, this is either an out or a fault
// If this component does not create / send exchanges, you may just throw an
// UnsupportedOperationException
if (exchange.getRole() == Role.CONSUMER)
{
onConsumerExchange(exchange);
}
// The component acts as a provider, this means that another component has requested our
// service
// As this exchange is active, this is either an in or a fault (out are send by this
// component)
else if (exchange.getRole() == MessageExchange.Role.PROVIDER)
{
onProviderExchange(exchange);
}
// Unknown role
else
{
throw new MessagingException("HandlerBean.onMessageExchange(): Unknown role: " + exchange.getRole());
}
}
/**
* handles the incoming consumer messages
*
* @param exchange
* @throws MessagingException
*/
private void onConsumerExchange(MessageExchange exchange) throws MessagingException
{
// Out message
if (exchange.getMessage("out") != null)
{
exchange.setStatus(ExchangeStatus.DONE);
channel.send(exchange);
}
// Fault message
else if (exchange.getFault() != null)
{
exchange.setStatus(ExchangeStatus.DONE);
channel.send(exchange);
}
// This is not compliant with the default MEPs
else
{
throw new MessagingException("HandlerBean.onConsumerExchange(): Consumer exchange is ACTIVE, but no out or fault is provided");
}
}
/**
* handles the incoming provider messages
*
* @param exchange
* @throws MessagingException
*/
private void onProviderExchange(MessageExchange exchange) throws MessagingException
{
// Exchange is finished
if (exchange.getStatus() == ExchangeStatus.DONE)
{
return;
}
// Exchange has been aborted with an exception
else if (exchange.getStatus() == ExchangeStatus.ERROR)
{
return;
}
// Fault message
else if (exchange.getFault() != null)
{
exchange.setStatus(ExchangeStatus.DONE);
channel.send(exchange);
}
else
{
NormalizedMessage in = exchange.getMessage("in");
if (in == null)
{
// no in message - strange
throw new MessagingException("HandlerBean.onProviderExchange(): Exchange has no IN message");
}
else
{
String fileName = null;
DataHandler content = null;
Set attNames = in.getAttachmentNames();
Iterator it = attNames.iterator();
if (attNames.size()==1)
{
if (it.hasNext())
{
try
{
fileName = it.next().toString();
content = in.getAttachment(fileName);
File f = File.createTempFile("tmp_", fileName);
FileOutputStream fos = new FileOutputStream(f);
content.writeTo(fos);
fos.flush();
fos.close();
// for the sake of simplicity only return the file received as attachment
NormalizedMessage out = exchange.createMessage();
// set the content to dummy xml tag
out.setContent(new StringSource("<payload/>"));
FileDataSource fds = new FileDataSource(f);
InputStream is = fds.getInputStream();
// create a handler for the attachment
DataHandler dh = new DataHandler(new StreamDataSource(is, fds.getContentType()));
// and add it to the message
out.addAttachment(fileName, dh);
// prepare and send the exchange
exchange.setMessage(out, "out");
channel.send(exchange);
f.deleteOnExit();
}
catch (IOException ex)
{
throw new MessagingException("HandlerBean.onProviderExchange(): " + ex.getLocalizedMessage());
}
}
}
else
{
// more or less than one attachment
throw new MessagingException("HandlerBean.onProviderExchange(): Wrong message format (invalid attachment count)");
}
}
}
}
}
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Now the handler SU is ready for work. Let's move on to creating the service assembly.
Proceed to the next step
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