Creating Applications Using JMS
Questions · Jobs · Tags · Users · Badges · Ask QueueSender extends MessageProducer, and provides some additional queue-specific methods. The same relationship exists between QueueReceiver and MessageConsumer. QueueConnection, QueueSession to their XA equivalent and for that I would need to use. JMS modules contains configuration resources (such as queues, topics, and connections A queue sender (producer) sends a message to a specific queue. .. QueueSessions, and consists of a connection to a JMS PTP provider created by. Creates a QueueSender object to send messages to the specified queue. Gets the queue session associated with this XAQueueSession. . The noLocal value must be supported by destinations that are topics. .. a new sequence of messages that have no ordering relationship with the messages it has previously sent.
They represent your connection to a server and you use them to create other objects, but you don't normally do your work by using them directly. The QueueSession and TopicSession classes are also similar to JDBC connections in that you use them to create objects, but again, you don't interact with them directly to send and receive messages.
The session objects let you create the senders, receivers, queues, and topics you need to actually send and receive messages. One of the big benefits of JMS is that you can perform message operations as part of a transaction. When you create a QueueSession or a TopicSession, you can specify that the session is transactional. The reason transactions are so important for messaging is that you get into situations in which you read a message off a message queue and then try to insert the message in a database.
If the database operation fails, you can't just stick the message back on the queue. If the operation is transactional, however, when the database operation fails, your message stays in the queue. Transactions can also ensure that the messaging system delivers the messages in the order you send them. Next, you use the QueueConnection to create a QueueSession.
Next, you create the Queue although you usually look for the queue in the naming service first, in case someone has already created it.
When you create the queue, you must give it a name. Every queue must have a unique name. After you have a Queue, you're almost ready. All you need is a QueueSender to send messages on the queue and one or more Message objects.
Understanding WebLogic JMS
You use the QueueSession to create both the QueueSender and the messages. 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.
- Programming WebLogic JMS
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.
The following table describes the fields in the message headers and shows how values are defined for each field. There are two common applications for this field. The second application is to use the JMSCorrelationID field to carry any String you choose, enabling a series of messages to be linked with some application-determined value.
java - MessageConsumer/MessageProducer vs QueueSender/QueueReceiver - Stack Overflow
This field is set on the producer or as parameter sent by the application before send. When a persistent message is sent, it is stored in the WebLogic Persistent Store.
The send operation is not considered successful until delivery of the message can be guaranteed. A persistent message is guaranteed to be delivered at least once. WebLogic JMS does not store non-persistent messages in the persistent store. This mode of operation provides the lowest overhead.
They are guaranteed to be delivered at least once unless there is a system failure, in which case messages may be lost. If a connection is closed or recovered, all non-persistent messages that have not yet been acknowledged will be redelivered.
Once a non-persistent message is acknowledged, it will not be redelivered. This value is overwritten by a call to producer. The values set by the producer can be queried using the message supplied to producer.
Using Message-Driven Bean and JMS Queue with ADF
This field is set by the application before send and depends on timeToDeliver, which is set on the producer. This field can be used to sort messages in a destination and to select messages. This field is set when creating producer or as parameter sent by the application before send. When a message is received, its destination value must be equivalent to the value assigned when it was sent. This field is set by the application before send.
Depends on timeToLive, which is set on the producer or as a parameter sent by the application to send. If the application specifies time-to-live as 0, JMSExpiration is set to 0, which means the message never expires.
WebLogic JMS removes expired messages from the system to prevent their delivery. This field is set internally by send.