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Connections support concurrent use, enabling multiple threads to access the object simultaneously.
The following table describes the Connection subclasses.
To learn how to use the Connection class within an application, see Chapter 5,
Developing a Basic JMS Application, or the javax.jms.Connection Javadoc at
http:java.sun.comjavaee5docsapijavaxjmsConnection.html .
2.4.3 Session
A Session object defines a serial order for the messages produced and consumed, and can create multiple message producers and message consumers. The same thread can
be used for producing and consuming messages. If an application wants to have a separate thread for producing and consuming messages, the application should create
a separate session for each function.
A Session is created by a Connection see Section 2.4.2, Connection
.
2.4.3.1 WebLogic JMS Session Guidelines
The JMS 1.1 Specification, at http:java.sun.comproductsjmsdocs.html
, allows for a generic session to have a MessageConsumer for any type of Destination
object. However, WebLogic JMS does not support having both types of MessageConsumer QueueConsumer and TopicSubscriber for a single session. In
addition, having multiple consumers for a single session is not a common practice. The following commonly-used scenarios are supported, however:
■
Using a single session with both a QueueSender and a TopicSubscriber and vice-versa: QueueConsumer and TopicPublisher.
■
Multiple MessageProducers of any type.
2.4.3.2 Session Subclasses
The following table describes the Session subclasses.
Note: For this release, you can use the JMS Version 1.1 specification
connection objects or you can choose to use the subclasses.
Table 2–5 Connection Subclasses
Subclass. . . In Messaging
Model. . .
Is Used to Create. . .
QueueConnection PTP
QueueSessions, and consists of a connection to a JMS PTP provider created by
QueueConnectionFactory. TopicConnection
Pubsub TopicSessions, and consists of a connection to a
JMS pubsub provider created by TopicConnectionFactory.
Note: A session and its message producers and consumers can only
be accessed by one thread at a time. Their behavior is undefined if multiple threads access them simultaneously.
Understanding WebLogic JMS 2-11
To learn how to use the Session class within an application, see Chapter 5, Developing
a Basic JMS Application, or the javax.jms.Session, at
http:java.sun.comjavaee5docsapijavaxjmsSession.html , and
weblogic.jms.extensions.WLSession javadocs.
2.4.3.3 Non-Transacted Session
In a non-transacted session, the application creating the session selects one of the five acknowledge modes defined in the following table.
Table 2–6 Session Subclasses
Subclass. . . In Messaging Model. . .
Provides a Context for. . .
QueueSession PTP
Producing and consuming messages for a JMS PTP provider. Created by QueueConnection.
TopicSession Pubsub
Producing and consuming messages for a JMS pubsub provider. Created by TopicConnection.
Table 2–7 Acknowledge Modes Used for Non-Transacted Sessions
Acknowledge Mode Description
AUTO_ACKNOWLEDGE The Session object acknowledges receipt of a message once
the receiving application method has returned from processing it.
CLIENT_ACKNOWLEDGE The Session object relies on the application to call an
acknowledge method on a received message. Once the method is called, the session acknowledges all messages
received since the last acknowledge.
This mode allows an application to receive, process, and acknowledge a batch of messages with one call.
Note: In the Administration Console, if the Acknowledge
Policy attribute on the connection factory is set to Previous, but you want to acknowledge all received messages for a
given session, then use the last message to invoke the acknowledge method.
For more information on the Acknowledge Policy attribute, see JMS Connection Factory: Configuration: General in the
Oracle WebLogic Server Administration Console Help. DUPS_OK_ACKNOWLEDGE
The Session object acknowledges receipt of a message once the receiving application method has returned from
processing it; duplicate acknowledges are permitted. This mode is most efficient in terms of resource usage.
Note: You should avoid using this mode if your application
cannot handle duplicate messages. Duplicate messages may be sent if an initial attempt to deliver a message fails.
2-12 Programming JMS for Oracle WebLogic Server
2.4.3.4 Transacted Session
