Relationship between queuesession and queuesender in jms api

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relationship between queuesession and queuesender in jms api

A sender JMS client can be a remote (standalone) client or a client residing on The SimpleClient class sends several messages to a queue. QueueSession queueSession = null; Queue queue = null; QueueSender catch ( NamingException e) { avesisland.infon("Could not create JNDI API" Finally, close connection. Once you gain an understanding of the JMS general API, the rest of the JMS API is Queue connection factory Queueconnection Queue session Queuesender. JMS is similar to JDBC in that it is a standard API for existing message Figure shows the relationship between connections, sessions, You use the QueueSession to create both the QueueSender and the messages.

Create a queue sender for queue0 and create a message. Send the "Hello" message to queue0. Close the queue connection. This will in turn close both the session and the QueueSender. The full source code for the sender application is shown below: This means that the message will be lost in case the JMS server crashes.

Instead of a QueueSender object, the receiver application creates a QueueReceiver from which messages can be received synchronously. Note that the receiver application must start the connection before any messages can be received.

Point to Point Messaging Program

The receiver application uses a non-transacted session with automatic message acknowledgement. This means that message will automatically be acknowledged by the session right before the receive method returns the message to the application.

Below is the source for the Receiver class: If a client want to temporarily stop delivery of messages, the connection can be stopped and then re-started later. A message listener is a regular Java class that implements the MessageListener interface.

relationship between queuesession and queuesender in jms api

This interface has a single onMessage method, which is called by JMS when messages arrive at a destination. As with the synchronous receiver, the AsyncReceiver class performs the same initial steps to create a QueueReceiver. Then, the setMessageListener method is called to register this as a message listener.

relationship between queuesession and queuesender in jms api

As with a synchronous receiver, messages will not be delivered until the start method is called on the connection. Since acknowledge mode is set to automatic, JMS will acknowledge messages right after calls to the onMessage method returns. Note that onMessage is not allowed to throw any exceptions. You must catch all exceptions and deal with them somehow in the onMessage method.

In the synchronous receiver, the receive method can raise an exception if the JMS provider fails. In this case, the program sends "Hello" messages over a message queue. Of course, instead of creating a QueueSender, you create a QueueReceiver. There are two different ways to receive messages.

You can call the receive method, which waits for messages, or you can create a listener object that receives messages when they become available. Notice that most of the setup is the same as in Listing You tell the QueueReceiver about your message listener and it will automatically let you know when a message comes in. Although JMS allows you to have multiple receivers on a queue, it is up to the individual implementations to decide how to handle multiple receivers.

Some might distribute the messages evenly across all receivers, and others might just send all the messages to the first receiver you create. Note Because sessions are single-threaded, you can only process one message at a time.

If you need to process multiple messages concurrently, you must create multiple sessions. Publishing Messages Although the overall concept of publish-subscribe is a bit different from point-to-point messages, the JMS calls for creating a topic and publishing messages are remarkably similar to the calls for sending queue messages. In fact, if you go through the program in Listing You must also change the createSender call to createPublisher. As with queues, each topic must have a unique name.

Unlike queues, in which you only have one receiver, you normally have many subscribers to a topic.

TIBCO Designer Tutorial - Send and Receive JMS Messages

You can also have multiple publishers. Your clients will just see more messages than they do if only one copy is running. Subscribing to Topics Subscribing to a topic is just as easy as listening on a queue. Again, you can just about convert the program in Listing The actual listener implementation for topics is identical to the one for queues.

Durable Subscriptions Most pub-sub systems you see today deal with frequently published data and tend to provide real-time monitoring and status updates.

Posting a message in JMS queue using JAVA - Stack Overflow

Pub-sub is good for these kinds of operations. Many pub-sub implementations have a peculiar limitation that makes them only suitable for applications with frequently published data-more specifically, applications in which it doesn't matter if you miss a message because there will be another one in a few minutes.

The reason pub-sub usually only works in these types of applications is that pub-sub doesn't usually have the concept of a persistent, or durable subscription. For example, suppose you are publishing flight cancellations for LaGuardia Airport.

Although it's true that they do seem to occur often enough that there will be another one in a few minutes, you really don't want to miss one. Now, suppose you have a program that makes a list of passengers who need to be rebooked for the next available flight tomorrow, next week, sometime next year, and so on.

If the program shuts down for a few minutes, it might miss three or four cancel lations! You want the message server to hold on to your messages while your program is down.

JMS supports durable subscription. After you create a durable subscription, the JMS server keeps any messages you miss while your program isn't running.