com.ninecode.email.beans.master
Class EmailDispatcher

java.lang.Object
  |
  +--com.ninecode.email.beans.master.EmailDispatcher

All Implemented Interfaces:

EnterpriseBean, MessageDrivenBean, MessageListener, Serializable

public class EmailDispatcher

extends Object

implements MessageDrivenBean, MessageListener

Message driven bean reads from a queue and dispatches to topics based on subject. The plan was to examine the Subject property set on a BytesMessage and try to find a matching Topic. To do that it converts the subject to lower case so the case-sensitivity of the lookup doesn't matter. It also trys "jms/" + topic in the case of a failed lookup. If no topic is found it sends a message to the output queue (return to sender) with a "help" message. This, however, is not allowed since arbitrary jndi lookups are not allowed. So... Another method is used. This is a configured list of subject-topic pairs that have a direct mapping. This list can't be dynamic due to the life-cycle of the message bean. Each message driven bean that is in the list would have it's own "help" command. That is, a message with subject xxx would be forwarded on to the topic associated with xxx and if the message body is the text string "help" (case-insensitive) it would answer with some help text. If no topic can be found using the above mechanisms it responds with the list of subjects it was configured with and a helpful message that says ask them for help on the topic. If a matching topic is found the message is essentially forwarded to the topic.

See Also:

Serialized Form

Field Summary

protected EmailProperties

mMap The list of subject-topic pairs.

Constructor Summary

EmailDispatcher()
Creates a EmailDispatcher bean.

Method Summary

void	bounceMessage(Message message, String subject, String content) Reply with help for unhandled messages.
protected void	dispatch(Message message) Dispatch the message.
void	ejbCreate() Startup call.
void	ejbRemove() Shutdown call.
void	forwardMessage(Message message, String name) Forward a jms message to the topic given.
byte[]	getBytes(BytesMessage message) Read all bytes from a bytes message.
protected String	getTopics() Get the list of configured topics.
void	helpMessage(Message message) Send help messages to all topics.
protected void	initializeMapping() Internalize the configured environment "Subject Topic Map".
void	onMessage(Message message) Process a message.
void	setMessageDrivenContext(MessageDrivenContext mdc) Remember the context for this instance.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

mMap

protected EmailProperties mMap

The list of subject-topic pairs.

Constructor Detail

EmailDispatcher

public EmailDispatcher()

Creates a EmailDispatcher bean. Life cycle:

constructor

set context

create

message

remove

Method Detail

ejbCreate

public void ejbCreate()

Startup call.

ejbRemove

public void ejbRemove()
               throws EJBException

Shutdown call.

Specified by:

ejbRemove in interface MessageDrivenBean

EJBException

initializeMapping

protected void initializeMapping()

Internalize the configured environment "Subject Topic Map". The "Subject Topic Map" item within the "java:comp/env" context is fetched and iterpreted as a list of subject topic pairs. This is cached in the mMap member field.

getBytes

public byte[] getBytes(BytesMessage message)
                throws JMSException

Read all bytes from a bytes message. Necessary because of the poor API available on bytes messages. This isn't really efficient, maybe we should put the size in the message first.

JMSException

forwardMessage

public void forwardMessage(Message message,
                           String name)
                    throws NamingException,
                           JMSException

Forward a jms message to the topic given.

Parameters:

message - The message to forward.

name - The topic name. A lookup is performed on this name within the "java:comp/env" environment.

NamingException

JMSException

helpMessage

public void helpMessage(Message message)
                 throws NamingException,
                        JMSException

Send help messages to all topics.

Parameters:

message - The help message.

NamingException

JMSException

getTopics

protected String getTopics()

Get the list of configured topics.

Returns:

The list of topics separated by spaces.

bounceMessage

public void bounceMessage(Message message,
                          String subject,
                          String content)
                   throws NamingException,
                          JMSException

Reply with help for unhandled messages.

Parameters:

message - The message to bounce.

NamingException

JMSException

dispatch

protected void dispatch(Message message)

Dispatch the message.

Parameters:

message - The message to dispatch.

setMessageDrivenContext

public void setMessageDrivenContext(MessageDrivenContext mdc)
                             throws EJBException

Remember the context for this instance.

Specified by:

setMessageDrivenContext in interface MessageDrivenBean

EJBException

onMessage

public void onMessage(Message message)

Process a message.

Specified by:

onMessage in interface MessageListener

Parameters:

message - The message to process.