Sun Java System Messaging Server 6.3 Administration Guide

22.1 JMQ Notification Overview

The Messaging Server notification plug-in allows you to deliver notification messages to a messaging service or event service. The messaging service sends the notifications to consumers (client interfaces), which filter and deliver the messages to specified users.

For example, when new email arrives in a user's mailbox, the notification plug-in delivers a notification message to the messaging service. The message consumer, a component of the messaging service, receives the notification and sends it to the user's email client (such as Communications Express or Mozilla mail). The email client can then display a pop-up on the user's computer screen: “You have received a new message.”

Another example: if a user's mailbox exceeds its quota, the notification plug-in produces an over-quota notification message. The message consumer sends a warning to the user and to an administrator who needs to be informed of the event.

22.1.1 Two Notification Messaging Services

You can configure Messaging Server to deliver notifications to two different messaging services:

The Message Queue service implements the Java Messaging Service (JMS) specification, providing a message broker, interfaces to create clients that produce or consume messages, and administrative services and control. Message Queue follows the JMS standard for routing and delivery functions, protocols, and message formats.

The Event Notification Service is a component bundled with Messaging Server and Sun Java System Calendar Server. It is a proprietary service that uses a publish/subscribe architecture for sending and receiving event notifications.

You can configure a notification producer for Message Queue, for the Event Notification Service, or for both services.

Note –

This chapter describes how to configure notifications for Message Queue only.

For information about the Event Notification Service, see the Sun Java System Communications Suite Event Notification Service Guide.

22.1.2 Notification Plug-ins

To enable Messaging Server to produce notifications to Message Queue or the Event Notification Service, you must configure a plug-in for that service:

For information on how to load the iBiff plug-in and configure the Event Notification Service, see “Appendix B: Administering Event Notification Service in Messaging Server,” in the Sun Java System Messaging Server Administration Guide.

22.1.3 Benefits of Using JMQ Notification

The JMQ notification plug-in, with Message Queue, provides the following benefits: Publishing to a Topic or a Queue

A topic and queue use different messaging delivery patterns; each one can be configured in a Message Queue service.

Topic. When a message producer sends a message to a topic, a publish/subscribe architecture is used. In this broadcast pattern, a producer sends a message to a topic destination. Any number of consumers can be subscribed to this topic destination. Each consumer subscribed to the topic gets its own copy of the message. If no consumers are subscribed to the topic, the message is discarded.

The Event Notification Service also uses a publish/subscribe architecture; it is similar to the topic pattern defined in Message Queue.

Queue. When a message producer sends a message to a queue, a point-to-point architecture is used. In this pattern, a producer sends a message to a queue destination from which only one consumer can receive it. If several consumers are waiting for messages from the queue, only one subscriber will receive the message. If no consumers are waiting, the message is held until either the message times out, or a consumer expresses an interest in the queue.

Producing messages to a queue allows you to spread the message load across multiple consumers. Using Multiple JMQ Notification Plug-ins

You can configure from one to five notification plug-ins.

Messaging Server provides a plug-in library at the following default location:


You use the configutil utility to specify parameters for a plug-in and to point the plug-in to the library of executable code.

If you specify more than one plug-in, each plug-in produces notification messages independently of the others. For example, if two plug-ins are configured with a delete-message parameter, and a message is deleted from a user's mailbox, both plug-ins will produce a notification message.

By configuring multiple plug-ins, you can take advantage of different message-distribution patterns for different purposes. For example, you could configure three different plug-ins to produce messages Configuring Parameters for a Notification Plug-in

For each plug-in you configure, you must define a separate set of configutil parameters.

The parameters determine two kinds of information:

For instructions on how to configure a plug-in, see To Configure a JMQ Notification Plug-in.