Event emission and storage

Events for state changes can be generated for executing business processes, human tasks, or both.

Two infrastructures emit or store the events, such that those events can be retrieved by applications. Applications might use events to monitor business processes and to analyze the history of business processes, or human tasks, or both.

Task events, for example, can be emitted without having a business process involved. These events can be consumed by the audit trail and the Common Event Infrastructure (CEI). This applies to standalone tasks, purely human tasks, and tasks invoked by application components other than business processes.

Because the generation of events impacts system performance, you can select the infrastructure to be used to store and emit events:

Common Event Infrastructure
Events can be both stored and published to subscribing applications. To use this event infrastructure, make sure that the Common Event Infrastructure is installed and configured.

Use event emission that is based on the Common Event Infrastructure to retrieve events in the format of Common Base Events, through the application programming interface (API) of the Common Event Infrastructure. You can connect consuming applications either by subscription or by using the query-oriented interface of the Common Event Infrastructure.

Event emission that is based on the Common Event Infrastructure has considerably greater impact on system performance than have audit log events. However, it provides greater flexibility for consuming applications.

Audit trail
Events are stored as records of a table in a relational database.

This is a fast event-storing infrastructure that has little impact on performance. Consuming applications need Structured Query Language (SQL) queries to retrieve the events from the database.

You can select either, both, or neither of the infrastructures. Selecting an infrastructure does not imply that events are necessarily stored or emitted. The selection enables the infrastructure, while you can control the actual generation of events later, by additional mechanisms. However, the enablement of an infrastructure results in a basic overhead that affects system performance.

Related information
Configuring the Common Event Infrastructure

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Last updated: Tue Feb 21 17:19:16 2006

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