org.apache.activemq.web

Class MessageListenerServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

org.apache.activemq.web.MessageServletSupport

org.apache.activemq.web.MessageListenerServlet

All Implemented Interfaces:

Serializable, Servlet, ServletConfig

Direct Known Subclasses:

AjaxServlet

public class MessageListenerServlet
extends MessageServletSupport

A servlet for sending and receiving messages to/from JMS destinations using HTTP POST for sending and HTTP GET for receiving.

You can specify the destination and whether it is a topic or queue via configuration details on the servlet or as request parameters.

For reading messages you can specify a readTimeout parameter to determine how long the servlet should block for. The servlet can be configured with the following init parameters:

defaultReadTimeout

The default time in ms to wait for messages. May be overridden by a request using the 'timeout' parameter

maximumReadTimeout

The maximum value a request may specify for the 'timeout' parameter

maximumMessages

maximum messages to send per response

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
MessageListenerServlet()

Method Summary

Methods

Modifier and Type	Method and Description
void	destroy()
protected void	doGet(HttpServletRequest request, HttpServletResponse response) Supports a HTTP DELETE to be equivlanent of consuming a singe message from a queue
protected void	doMessages(AjaxWebClient client, HttpServletRequest request, HttpServletResponse response) Reads a message from a destination up to some specific timeout period
protected void	doPost(HttpServletRequest request, HttpServletResponse response) Sends a message to a destination or manage subscriptions.
protected AjaxWebClient	getAjaxWebClient(HttpServletRequest request)
protected long	getReadTimeout(HttpServletRequest request)
void	init()
protected void	writeMessageResponse(PrintWriter writer, Message message, String id, String destinationName)

Methods inherited from class org.apache.activemq.web.MessageServletSupport

appendParametersToMessage, asBoolean, asBoolean, asDestination, asInt, asInteger, asLong, asLong, asString, getDestination, getDestination, getDestinationFromURI, getPostedMessageBody, getSelector, getSendPriority, getSendTimeToLive, init, isSendPersistent, isSync, isTopic

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, log, log

Methods inherited from class java.lang.Object

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

Constructor Detail

MessageListenerServlet

public MessageListenerServlet()

Method Detail

init

public void init()
          throws ServletException

Overrides:

init in class GenericServlet

Throws:

ServletException

doPost

protected void doPost(HttpServletRequest request,
          HttpServletResponse response)
               throws ServletException,
                      IOException

Sends a message to a destination or manage subscriptions. If the the content type of the POST is application/x-www-form-urlencoded, then the form parameters "destination", "message" and "type" are used to pass a message or a subscription. If multiple messages or subscriptions are passed in a single post, then additional parameters are shortened to "dN", "mN" and "tN" where N is an index starting from 1. The type is either "send", "listen" or "unlisten". For send types, the message is the text of the TextMessage, otherwise it is the ID to be used for the subscription. If the content type is not application/x-www-form-urlencoded, then the body of the post is sent as the message to a destination that is derived from a query parameter, the URL or the default destination.

Overrides:

doPost in class HttpServlet

Parameters:

request -

response -

Throws:

ServletException

IOException

doGet

protected void doGet(HttpServletRequest request,
         HttpServletResponse response)
              throws ServletException,
                     IOException

Supports a HTTP DELETE to be equivlanent of consuming a singe message from a queue

Overrides:

doGet in class HttpServlet

Throws:

ServletException

IOException

doMessages

protected void doMessages(AjaxWebClient client,
              HttpServletRequest request,
              HttpServletResponse response)
                   throws JMSException,
                          IOException

Reads a message from a destination up to some specific timeout period

Parameters:

client - The webclient

request -

response -

Throws:

ServletException

IOException

JMSException

writeMessageResponse

protected void writeMessageResponse(PrintWriter writer,
                        Message message,
                        String id,
                        String destinationName)
                             throws JMSException,
                                    IOException

Throws:

JMSException

IOException

getAjaxWebClient

protected AjaxWebClient getAjaxWebClient(HttpServletRequest request)

getReadTimeout

protected long getReadTimeout(HttpServletRequest request)

Returns:

the timeout value for read requests which is always >= 0 and <= maximumReadTimeout to avoid DoS attacks

destroy

public void destroy()

Specified by:

destroy in interface Servlet

Overrides:

destroy in class GenericServlet