Examples of org.apache.activemq.MessageAvailableConsumer

org.apache.activemq.MessageAvailableConsumer
An extended JMS interface that adds the ability to be notified when a message is available for consumption using the receive*() methods which is useful in Ajax style subscription models. @version $Revision: 1.1 $


            if (log.isDebugEnabled()) {
                log.debug("Receiving message(s) from: " + destination + " with timeout: " + timeout);
            }


            MessageAvailableConsumer consumer = (MessageAvailableConsumer) client.getConsumer(destination);
            Continuation continuation = null;
            Listener listener = null;
            Message message = null;


            // write a responds
            response.setContentType("text/xml");
            PrintWriter writer = response.getWriter();


            if (ajax)
                writer.println("<ajax-response>");


            // Only one client thread at a time should poll for messages.
            if (client.getSemaphore().tryAcquire()) {
                try {
                    // Look for any available messages
                    message = consumer.receive(timeout);


                    // handle any message(s)
                    if (message == null) {
                        // No messages so OK response of for ajax else no
                        // content.
                        response.setStatus(ajax ? HttpServletResponse.SC_OK : HttpServletResponse.SC_NO_CONTENT);
                    } else {
                        // We have at least one message so set up the
                        // response
                        response.setStatus(HttpServletResponse.SC_OK);
                        String type = getContentType(request);
                        if (type != null)
                            response.setContentType(type);


                        // send a response for each available message (up to
                        // max
                        // messages)
                        while ((maxMessages < 0 || messages < maxMessages) && message != null) {
                            // System.err.println("message["+messages+"]="+message);
                            if (ajax) {
                                writer.print("<response type='object' id='");
                                writer.print(request.getParameter("id"));
                                writer.println("'>");
                            } else
                                // only ever 1 message for non ajax!
                                setResponseHeaders(response, message);


                            writeMessageResponse(writer, message);


                            if (ajax)
                                writer.println("</response>");


                            // look for next message
                            message = consumer.receiveNoWait();
                            messages++;
                        }
                    }
                } finally {
                    client.getSemaphore().release();

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                        Listener listener = getListener(request);
                        Map<MessageAvailableConsumer, String> consumerIdMap = getConsumerIdMap(request);
                        Map<MessageAvailableConsumer, String> consumerDestinationMap = getConsumerDestinationNameMap(request);
                        client.closeConsumer(destination); // drop any existing
                        // consumer.
                        MessageAvailableConsumer consumer = (MessageAvailableConsumer)client.getConsumer(destination, request.getHeader(WebClient.selectorName));


                        consumer.setAvailableListener(listener);
                        consumerIdMap.put(consumer, message);
                        consumerDestinationMap.put(consumer, destinationName);
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Subscribed: " + consumer + " to " + destination + " id=" + message);
                        }
                    } else if ("unlisten".equals(type)) {
                        Map<MessageAvailableConsumer, String> consumerIdMap = getConsumerIdMap(request);
                        Map consumerDestinationMap = getConsumerDestinationNameMap(request);
                        MessageAvailableConsumer consumer = (MessageAvailableConsumer)client.getConsumer(destination, request.getHeader(WebClient.selectorName));


                        consumer.setAvailableListener(null);
                        consumerIdMap.remove(consumer);
                        consumerDestinationMap.remove(consumer);
                        client.closeConsumer(destination);
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Unsubscribed: " + consumer);

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        message = (Message)request.getAttribute("message"); 
        
        synchronized (client) {


            List consumers = client.getConsumers();
            MessageAvailableConsumer consumer = (MessageAvailableConsumer)request.getAttribute("consumer");


            if (message == null) {
                // Look for a message that is ready to go
                for (int i = 0; message == null && i < consumers.size(); i++) {
                    consumer = (MessageAvailableConsumer)consumers.get(i);
                    if (consumer.getAvailableListener() == null) {
                        continue;
                    }
    
                    // Look for any available messages
                    message = consumer.receive(10);
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("received " + message + " from " + consumer);
                    }
                }
            }


            if (message == null) {
                Continuation continuation = ContinuationSupport.getContinuation(request);
                
                if (continuation.isExpired()) {  
                    response.setStatus(HttpServletResponse.SC_OK);
                    StringWriter swriter = new StringWriter();
                    PrintWriter writer = new PrintWriter(swriter);
                    writer.println("<ajax-response>");
                    writer.print("</ajax-response>");


                    writer.flush();
                    String m = swriter.toString();
                    response.getWriter().println(m); 
                    
                    return;
                }


                continuation.setTimeout(timeout);
                continuation.suspend();
                
                // Fetch the listeners
                Listener listener = getListener(request);


                // register this continuation with our listener.
                listener.setContinuation(continuation);
                
                return;
            }
            
            // prepare the responds
            response.setContentType("text/xml");
            response.setHeader("Cache-Control", "no-cache");


            StringWriter swriter = new StringWriter();
            PrintWriter writer = new PrintWriter(swriter);


            Map<MessageAvailableConsumer, String> consumerIdMap = getConsumerIdMap(request);
            Map<MessageAvailableConsumer, String> consumerDestinationNameMap = getConsumerDestinationNameMap(request);
            response.setStatus(HttpServletResponse.SC_OK);
            writer.println("<ajax-response>");


            // Send any message we already have
            if (message != null) {
                String id = consumerIdMap.get(consumer);
                String destinationName = consumerDestinationNameMap.get(consumer);
                writeMessageResponse(writer, message, id, destinationName);
                
                messages++;
            }


            // Send the rest of the messages
            for (int i = 0; i < consumers.size() && messages < maximumMessages; i++) {
                consumer = (MessageAvailableConsumer)consumers.get(i);
                if (consumer.getAvailableListener() == null) {
                    continue;
                }


                // Look for any available messages
                while (messages < maximumMessages) {
                    message = consumer.receiveNoWait();
                    if (message == null) {
                        break;
                    }
                    messages++;
                    String id = consumerIdMap.get(consumer);

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            WebClient client = getWebClient(request);
            Destination destination = getDestination(client, request);
            if (destination == null) {
                throw new NoDestinationSuppliedException();
            }
            MessageAvailableConsumer consumer = (MessageAvailableConsumer)client.getConsumer(destination, request.getHeader(WebClient.selectorName));
            Message message = null;
            message = (Message)request.getAttribute("message"); 
            if (message != null) {
                // we're resuming continuation,
                // so just write the message and return
                writeResponse(request, response, message);
                return;
            }
            long timeout = getReadTimeout(request);


            if (LOG.isDebugEnabled()) {
                LOG.debug("Receiving message(s) from: " + destination + " with timeout: " + timeout);
            }


            Continuation continuation = null;
            Listener listener = null;
            


            // Look for any available messages
            message = consumer.receive(10);


            // Get an existing Continuation or create a new one if there are
            // no events.
            if (message == null) {
                continuation = ContinuationSupport.getContinuation(request);
                
                if (continuation.isExpired()) {
                    response.setStatus(HttpServletResponse.SC_NO_CONTENT);
                    return;
                }


                continuation.setTimeout(timeout);
                continuation.suspend();
                
                // Fetch the listeners
                listener = (Listener)consumer.getAvailableListener();
                if (listener == null) {
                    listener = new Listener(consumer);
                    consumer.setAvailableListener(listener);
                }


                // register this continuation with our listener.
                listener.setContinuation(continuation);
            }

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                        AjaxListener listener = client.getListener();
                        Map<MessageAvailableConsumer, String> consumerIdMap = client.getIdMap();
                        Map<MessageAvailableConsumer, String> consumerDestinationNameMap = client.getDestinationNameMap();
                        client.closeConsumer(destination); // drop any existing
                        // consumer.
                        MessageAvailableConsumer consumer = (MessageAvailableConsumer)client.getConsumer(destination, request.getHeader(WebClient.selectorName));


                        consumer.setAvailableListener(listener);
                        consumerIdMap.put(consumer, message);
                        consumerDestinationNameMap.put(consumer, destinationName);
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Subscribed: " + consumer + " to " + destination + " id=" + message);
                        }
                    } else if ("unlisten".equals(type)) {
                        Map<MessageAvailableConsumer, String> consumerIdMap = client.getIdMap();
                        Map<MessageAvailableConsumer, String> consumerDestinationNameMap = client.getDestinationNameMap();
                        MessageAvailableConsumer consumer = (MessageAvailableConsumer)client.getConsumer(destination, request.getHeader(WebClient.selectorName));


                        consumer.setAvailableListener(null);
                        consumerIdMap.remove(consumer);
                        consumerDestinationNameMap.remove(consumer);
                        client.closeConsumer(destination);
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Unsubscribed: " + consumer);

View Full Code Here

        }


        synchronized (client) {


            List<MessageConsumer> consumers = client.getConsumers();
            MessageAvailableConsumer consumer = null;
            if( undelivered_message != null ) {
                consumer = (MessageAvailableConsumer)undelivered_message.getConsumer();
            }


            if (message == null) {
                // Look for a message that is ready to go
                for (int i = 0; message == null && i < consumers.size(); i++) {
                    consumer = (MessageAvailableConsumer)consumers.get(i);
                    if (consumer.getAvailableListener() == null) {
                        continue;
                    }


                    // Look for any available messages
                    message = consumer.receive(10);
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("received " + message + " from " + consumer);
                    }
                }
            }


            // prepare the response
            response.setContentType("text/xml");
            response.setHeader("Cache-Control", "no-cache");


            if (message == null && client.getListener().getUndeliveredMessages().size() == 0) {
                Continuation continuation = ContinuationSupport.getContinuation(request);


                // Add a listener to the continuation to make sure it actually
                // will expire (seems like a bug in Jetty Servlet 3 continuations,
                // see https://issues.apache.org/jira/browse/AMQ-3447
                continuation.addContinuationListener(new ContinuationListener() {
                    @Override
                    public void onTimeout(Continuation cont) {
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Continuation " + cont.toString() + " expired.");
                        }
                    }


                    @Override
                    public void onComplete(Continuation cont) {
                        if (LOG.isDebugEnabled()) {
                           LOG.debug("Continuation " + cont.toString() + " completed.");
                        }
                    }
                });


                if (continuation.isExpired()) {
                    response.setStatus(HttpServletResponse.SC_OK);
                    StringWriter swriter = new StringWriter();
                    PrintWriter writer = new PrintWriter(swriter);
                    writer.println("<ajax-response>");
                    writer.print("</ajax-response>");


                    writer.flush();
                    String m = swriter.toString();
                    response.getWriter().println(m);


                    return;
                }


                continuation.setTimeout(timeout);
                continuation.suspend();
                LOG.debug( "Suspending continuation " + continuation );


                // Fetch the listeners
                AjaxListener listener = client.getListener();
                listener.access();


                // register this continuation with our listener.
                listener.setContinuation(continuation);


                return;
            }


            StringWriter swriter = new StringWriter();
            PrintWriter writer = new PrintWriter(swriter);


            Map<MessageAvailableConsumer, String> consumerIdMap = client.getIdMap();
            Map<MessageAvailableConsumer, String> consumerDestinationNameMap = client.getDestinationNameMap();
            response.setStatus(HttpServletResponse.SC_OK);
            writer.println("<ajax-response>");


            // Send any message we already have
            if (message != null) {
                String id = consumerIdMap.get(consumer);
                String destinationName = consumerDestinationNameMap.get(consumer);
                LOG.debug( "sending pre-existing message" );
                writeMessageResponse(writer, message, id, destinationName);


                messages++;
            }


            // send messages buffered while continuation was unavailable.
            LinkedList<UndeliveredAjaxMessage> undeliveredMessages = ((AjaxListener)consumer.getAvailableListener()).getUndeliveredMessages();
            LOG.debug("Send " + undeliveredMessages.size() + " unconsumed messages");
            synchronized( undeliveredMessages ) {
                for (Iterator<UndeliveredAjaxMessage> it = undeliveredMessages.iterator(); it.hasNext();) {
                    messages++;
                    UndeliveredAjaxMessage undelivered = it.next();
                    Message msg = undelivered.getMessage();
                    consumer = (MessageAvailableConsumer)undelivered.getConsumer();
                    String id = consumerIdMap.get(consumer);
                    String destinationName = consumerDestinationNameMap.get(consumer);
                    LOG.debug( "sending undelivered/buffered messages" );
                    LOG.debug( "msg:" +msg+ ", id:" +id+ ", destinationName:" +destinationName);
                    writeMessageResponse(writer, msg, id, destinationName);
                    it.remove();
                    if (messages >= maximumMessages) {
                        break;
                    }
                }
            }


            // Send the rest of the messages
            for (int i = 0; i < consumers.size() && messages < maximumMessages; i++) {
                consumer = (MessageAvailableConsumer)consumers.get(i);
                if (consumer.getAvailableListener() == null) {
                    continue;
                }


                // Look for any available messages
                while (messages < maximumMessages) {
                    message = consumer.receiveNoWait();
                    if (message == null) {
                        break;
                    }
                    messages++;
                    String id = consumerIdMap.get(consumer);

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     * @param response
     * @throws ServletException
     * @throws IOException
     */
    protected void doMessages(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        MessageAvailableConsumer consumer = null;


        try {
            WebClient client = getWebClient(request);
            Destination destination = getDestination(client, request);
            if (destination == null) {
                throw new NoDestinationSuppliedException();
            }
            consumer = (MessageAvailableConsumer) client.getConsumer(destination, request.getHeader(WebClient.selectorName));
            Continuation continuation = ContinuationSupport.getContinuation(request);


            // Don't allow concurrent use of the consumer. Do make sure to allow
            // subsequent calls on continuation to use the consumer.
            if (continuation.isInitial()) {
                synchronized (activeConsumers) {
                    if (activeConsumers.contains(consumer)) {
                        throw new ServletException("Concurrent access to consumer is not supported");
                    } else {
                        activeConsumers.add(consumer);
                    }
                }
            }


            Message message = null;


            long deadline = getReadDeadline(request);
            long timeout = deadline - System.currentTimeMillis();


            // Set the message available listener *before* calling receive to eliminate any
            // chance of a missed notification between the time receive() completes without
            // a message and the time the listener is set.
            synchronized (consumer) {
                Listener listener = (Listener) consumer.getAvailableListener();
                if (listener == null) {
                    listener = new Listener(consumer);
                    consumer.setAvailableListener(listener);
                }
            }


            if (LOG.isDebugEnabled()) {
                LOG.debug("Receiving message(s) from: " + destination + " with timeout: " + timeout);
            }


            // Look for any available messages (need a little timeout). Always
            // try at least one lookup; don't block past the deadline.
            if (timeout <= 0) {
                message = consumer.receiveNoWait();
            } else if (timeout < 10) {
                message = consumer.receive(timeout);
            } else {
                message = consumer.receive(10);
            }


            if (message == null) {
                handleContinuation(request, response, client, destination, consumer, deadline);
            } else {

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            WebClient client = getWebClient(request);
            Destination destination = getDestination(client, request);
            if (destination == null) {
                throw new NoDestinationSuppliedException();
            }
            MessageAvailableConsumer consumer = (MessageAvailableConsumer)client.getConsumer(destination, request.getHeader(WebClient.selectorName));
            Message message = null;
            message = (Message)request.getAttribute("message");
            if (message != null) {
                // we're resuming continuation,
                // so just write the message and return
                writeResponse(request, response, message);
                return;
            }
            long timeout = getReadTimeout(request);


            if (LOG.isDebugEnabled()) {
                LOG.debug("Receiving message(s) from: " + destination + " with timeout: " + timeout);
            }


            Continuation continuation = null;
            Listener listener = null;




            // Look for any available messages
            message = consumer.receive(10);


            // Get an existing Continuation or create a new one if there are
            // no events.
            if (message == null) {
                continuation = ContinuationSupport.getContinuation(request);


                if (continuation.isExpired()) {
                    response.setStatus(HttpServletResponse.SC_NO_CONTENT);
                    return;
                }


                continuation.setTimeout(timeout);
                continuation.suspend();


                // Fetch the listeners
                listener = (Listener)consumer.getAvailableListener();
                if (listener == null) {
                    listener = new Listener(consumer);
                    consumer.setAvailableListener(listener);
                }


                // register this continuation with our listener.
                listener.setContinuation(continuation);
            }

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                        AjaxListener listener = client.getListener();
                        Map<MessageAvailableConsumer, String> consumerIdMap = client.getIdMap();
                        Map<MessageAvailableConsumer, String> consumerDestinationNameMap = client.getDestinationNameMap();
                        client.closeConsumer(destination); // drop any existing
                        // consumer.
                        MessageAvailableConsumer consumer = (MessageAvailableConsumer)client.getConsumer(destination, request.getHeader(WebClient.selectorName));


                        consumer.setAvailableListener(listener);
                        consumerIdMap.put(consumer, message);
                        consumerDestinationNameMap.put(consumer, destinationName);
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Subscribed: " + consumer + " to " + destination + " id=" + message);
                        }
                    } else if ("unlisten".equals(type)) {
                        Map<MessageAvailableConsumer, String> consumerIdMap = client.getIdMap();
                        Map<MessageAvailableConsumer, String> consumerDestinationNameMap = client.getDestinationNameMap();
                        MessageAvailableConsumer consumer = (MessageAvailableConsumer)client.getConsumer(destination, request.getHeader(WebClient.selectorName));


                        consumer.setAvailableListener(null);
                        consumerIdMap.remove(consumer);
                        consumerDestinationNameMap.remove(consumer);
                        client.closeConsumer(destination);
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Unsubscribed: " + consumer);

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        }


        synchronized (client) {


            List<MessageConsumer> consumers = client.getConsumers();
            MessageAvailableConsumer consumer = null;
            if( undelivered_message != null ) {
                consumer = (MessageAvailableConsumer)undelivered_message.getConsumer();
            }


            if (message == null) {
                // Look for a message that is ready to go
                for (int i = 0; message == null && i < consumers.size(); i++) {
                    consumer = (MessageAvailableConsumer)consumers.get(i);
                    if (consumer.getAvailableListener() == null) {
                        continue;
                    }


                    // Look for any available messages
                    message = consumer.receive(10);
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("received " + message + " from " + consumer);
                    }
                }
            }


            // prepare the response
            response.setContentType("text/xml");
            response.setHeader("Cache-Control", "no-cache");


            if (message == null && client.getListener().getUndeliveredMessages().size() == 0) {
                Continuation continuation = ContinuationSupport.getContinuation(request);


                if (continuation.isExpired()) {
                    response.setStatus(HttpServletResponse.SC_OK);
                    StringWriter swriter = new StringWriter();
                    PrintWriter writer = new PrintWriter(swriter);
                    writer.println("<ajax-response>");
                    writer.print("</ajax-response>");


                    writer.flush();
                    String m = swriter.toString();
                    response.getWriter().println(m);


                    return;
                }


                continuation.setTimeout(timeout);
                continuation.suspend();
                LOG.debug( "Suspending continuation " + continuation );


                // Fetch the listeners
                AjaxListener listener = client.getListener();
                listener.access();


                // register this continuation with our listener.
                listener.setContinuation(continuation);


                return;
            }


            StringWriter swriter = new StringWriter();
            PrintWriter writer = new PrintWriter(swriter);


            Map<MessageAvailableConsumer, String> consumerIdMap = client.getIdMap();
            Map<MessageAvailableConsumer, String> consumerDestinationNameMap = client.getDestinationNameMap();
            response.setStatus(HttpServletResponse.SC_OK);
            writer.println("<ajax-response>");


            // Send any message we already have
            if (message != null) {
                String id = consumerIdMap.get(consumer);
                String destinationName = consumerDestinationNameMap.get(consumer);
                LOG.debug( "sending pre-existing message" );
                writeMessageResponse(writer, message, id, destinationName);


                messages++;
            }


            // send messages buffered while continuation was unavailable.
            LinkedList<UndeliveredAjaxMessage> undeliveredMessages = ((AjaxListener)consumer.getAvailableListener()).getUndeliveredMessages();
            LOG.debug("Send " + undeliveredMessages.size() + " unconsumed messages");
            synchronized( undeliveredMessages ) {
                for (Iterator<UndeliveredAjaxMessage> it = undeliveredMessages.iterator(); it.hasNext(); ) {
                    messages++;
                    UndeliveredAjaxMessage undelivered = it.next();
                    Message msg = (Message)undelivered.getMessage();
                    consumer = (MessageAvailableConsumer)undelivered.getConsumer();
                    String id = consumerIdMap.get(consumer);
                    String destinationName = consumerDestinationNameMap.get(consumer);
                    LOG.debug( "sending undelivered/buffered messages" );
                    LOG.debug( "msg:" +msg+ ", id:" +id+ ", destinationName:" +destinationName);
                    writeMessageResponse(writer, msg, id, destinationName);
                    it.remove();
                    if (messages >= maximumMessages) {
                        break;
                    }
                }
            }


            // Send the rest of the messages
            for (int i = 0; i < consumers.size() && messages < maximumMessages; i++) {
                consumer = (MessageAvailableConsumer)consumers.get(i);
                if (consumer.getAvailableListener() == null) {
                    continue;
                }


                // Look for any available messages
                while (messages < maximumMessages) {
                    message = consumer.receiveNoWait();
                    if (message == null) {
                        break;
                    }
                    messages++;
                    String id = consumerIdMap.get(consumer);

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