Nondurable Subscribers and Subscriptions

<< The createDurableSubscriber Method | A Durable Subscription Example >>

Nondurable Subscribers and Subscriptions

subscription also ends. Here, create stands for a call to Session.createConsumer with a Topic
argument, and close stands for a call to MessageConsumer.close. Any messages published to
the topic between the time of the first close and the time of the second create are not
consumed by the subscriber. In

Figure 317

, the subscriber consumes messages M1, M2, M5,

and M6, but messages M3 and M4 are lost.

With a durable subscriber, the subscriber can be closed and re-created, but the subscription
continues to exist and to hold messages until the application calls the unsubscribe method. In

Figure 318

, create stands for a call to Session.createDurableSubscriber, close stands for

a call to MessageConsumer.close, and unsubscribe stands for a call to Session.unsubscribe.
Messages published while the subscriber is closed are received when the subscriber is created
again. So even though messages M2, M4, and M5 arrive while the subscriber is closed, they are
not lost.

See

"A Java EE Application That Uses the JMS API with a Session Bean" on page 964

for an

example of a Java EE application that uses durable subscriptions. See

"A Message

Acknowledgment Example" on page 938

and the next section for examples of client

applications that use durable subscriptions.

Subscriber

Subscription

create

Subscriber

Subscription

create

FIGURE 317

Nondurable Subscribers and Subscriptions

Subscriber

create

M4 M5

Subscriber

create

Subscriber

create

unsubscribe

FIGURE 318

A Durable Subscriber and Subscription

Creating Robust JMS Applications

The Java EE 5 Tutorial · September 2007

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