Adapter Components of the Oracle CEP Event Processing Network

Overview of Creating Oracle CEP Applications 1-3

1.1.1.2 Channel

A channel is a component that represents the physical conduit through which events flow. Channels connect components that send events with components that receive events. For more information, see Chapter 9, Configuring Channels .

1.1.1.3 Processor

A processor is a component that executes user-defined event processing rules against the events offered by channels. The user-defined rules are written using either of the following: ■ Oracle Continuous Query Language Oracle CQL For more information, see: – Chapter 10, Configuring Oracle CQL Processors – Oracle Complex Event Processing CQL Language Reference ■ Event Processing Language EPL For more information, see: – Chapter 11, Configuring EPL Processors – Oracle Complex Event Processing EPL Language Reference

1.1.1.4 Event Bean

An event bean is a user-coded Plain Old Java Object POJO bean managed by Oracle CEP. Event beans are analogous to Spring beans, which are managed by the Spring framework, however they support event-based features, such as the specification of a suspend and resume methods. For more information, see Chapter 15, Configuring Custom Event Beans .

1.1.1.5 Spring Bean

A spring bean is a user-coded Plain Old Java Object POJO managed by the Spring framework. These components are not managed by Oracle CEP; for example, you cannot monitor these components, record and playback of events, and so on. If you require this additional functionality for your POJO, consider creating an Oracle CEP event bean instead. For more information, see Section 16, Configuring Custom Spring Beans .

1.1.1.6 Cache

A cache is a temporary storage area for events, created exclusively to improve the overall performance of your application and to handle large amounts of historical data. For more information, see: ■ Section 10.4, Configuring an Oracle CQL Processor Cache Source Note: Oracle CQL replaces Event Processing Language EPL in Oracle CEP 11g Release 1 11.1.1. Oracle CEP supports EPL for backwards compatibility. 1-4 Oracle Complex Event Processing Developers Guide ■ Section 11.3, Configuring an EPL Processor Cache Source ■ Chapter 12, Configuring Caching .

1.1.1.7 Table

A table is a component that connects a relational database table to the EPN as an event data source. You can access a relational database table from an Oracle CQL query using: ■ table source: using a table source, you may join a stream only with a NOW window and only to a single database table. For more information, Section 10.3, Configuring an Oracle CQL Processor Table Source . ■ Oracle JDBC data cartridge: using the Oracle JDBC data cartridge, you may integrate arbitrarily complex SQL queries and multiple tables and datasources with your Oracle CQL queries. For more information, see Understanding the Oracle JDBC Data Cartridge in the Oracle Complex Event Processing CQL Language Reference. In all cases, you must define datasources in the Oracle CEP server config.xml file. For more information, see Configuring Access to a Relational Database in the Oracle Complex Event Processing Administrators Guide. Oracle CEP relational database table event sources are pull data sources: that is, Oracle CEP will periodically poll the event source.

1.1.1.8 Nested Stages

When you define a child stage within a parent stage in an EPN, the child stage is said to be nested. Only the parent stage can specify the child stage as a listener. Example 1–1 shows the EPN assembly source in which HelloWorldBean is nested within the helloworldOutputChannel. Only the parent helloworldOutputChannel may specify the nested bean as a listener.