WebSphere WebSphere Enterprise Service Bus, Version 6.0.1 Operating Systems: AIX, HP-UX, Linux, Solaris, Windows

Planning to use the Common Event Infrastructure

The Common Event Infrastructure facilitates events.

Why and when to perform this task

The Common Event Infrastructure provides facilities for the generation, propagation, persistence, and consumption of events, but it does not define the actual events. When you plan how to use the event infrastructure in your system design, you need to understand the business concepts that are relevant, and map them to the appropriate components of your system design. You should provide the semantics of event management by defining event types and event groups, in the context of an architecture of event sources and event consumers.

Steps for this task

  1. Identify each event source. The event source is the application that creates the event. The event source passes the event object to the event infrastructure. The event infrastructure also stores the event object in a database for later retrieval. The role of the event infrastructure is to pass the event object onto any applications that express an interest in receiving it.
  2. Identify each event consumer. An event consumer is an application that can use the information that is contained in the event object. Event consumers typically process events from a number of event sources.
  3. Identify the hierarchy of the event correlation spheres and the identifiers for these spheres. Event consumers can use event correlation spheres to correlate events. The ECSEmitter class supports a hierarchy of correlation spheres by storing the current identifier and the parent identifier of the correlation spheres of an event in each event.
    Note: ECSEmitter and correlation sphere capabilities are provided through the Events service and not through the Common Event Infrastructure, itself.

    For example, a Business Process Execution Language (BPEL) activity opens a correlation sphere for the current activity that identifies the activity with the activity instance ID. The parent correlation sphere is the correlation sphere of the process instance on behalf of which the activity is run. The parent correlation sphere is identified by the process instance ID.

  4. Identify each event group. An event group defines the characteristics (property values) that all events of interest to a particular type of consumer can contain. Policies, such as access controls and distribution rules are assigned to the event groups to customize the behavior of the event infrastructure for each user group.

Example

WebSphere supplies a default event group that is defined to include all events. This event group is called Event groups list and has a Java Naming and Directory Interface (JNDI) name of com/ibm/events/configuration/event-groups/Default

The following figure shows the relationship between these objects:

Figure 1. The architecture of an event source (which creates events), an event consumer (which makes use of the event data), and an event group (which defines the characteristics and associated policies for each type of event).Diagram of the flow of events, from source to consumer.
Related tasks
Configuring the common event infrastructure
Using the Common Event Infrastructure

Task topic

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Timestamp iconLast updated: 13 Dec 2005
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