Java Reference
In-Depth Information
What Is the JMS API?
The Java Message Service is a Java API that allows applications to create, send, receive,
and read messages. Designed by Sun and several partner companies, the JMS API defines
a common set of interfaces and associated semantics that allow programs written in the
Java programming language to communicate with other messaging implementations.
The JMS API minimizes the set of concepts a programmer must learn in order to use mes-
saging products but provides enough features to support sophisticated messaging applica-
tions. It also strives to maximize the portability of JMS applications across JMS providers
in the same messaging domain.
The JMS API enables communication that is not only loosely coupled but also:
•
Asynchronous
: A JMS provider can deliver messages to a client as they arrive; a
client does not have to request messages in order to receive them.
•
Reliable
: The JMS API can ensure that a message is delivered once and only once.
Lower levels of reliability are available for applications that can afford to miss
messages or to receive duplicate messages.
The current version of the JMS specification is Version 1.1. You can download a copy
of the specification from the JMS web site:
http://www.oracle.com/technet-
When Can You Use the JMS API?
An enterprise application provider is likely to choose a messaging API over a tightly
coupled API, such as a remote procedure call (RPC), under the following circumstances.
• The provider wants the components not to depend on information about other com-
ponents' interfaces, so components can be easily replaced.
• The provider wants the application to run whether or not all components are up and
running simultaneously.
• The application business model allows a component to send information to another
and to continue to operate without receiving an immediate response.
For example, components of an enterprise application for an automobile manufacturer can
use the JMS API in situations like these:
• The inventory component can send a message to the factory component when the
inventory level for a product goes below a certain level so the factory can make
more cars.
• The factory component can send a message to the parts components so the factory
can assemble the parts it needs.
