Introduction to Execution Plans

The event processor performs complex event processing and wraps the Siddhi engine. It uses multiple processing configurations called execution plans. An execution plan is an instance of the complex event processing runtime, which is responsible for the actual processing of events. A typical execution plan consists of a set of related query expressions and relevant input and output configurations. Each execution plan wraps a Siddhi engine inside to perform the complex event processing.

The event processor allows users to configure multiple execution plans, providing multiple isolated processing environments for different purposes. An execution plan consists of the following:

Siddhi runtime configurations

Configuration parameters that are specific to the underlying Siddhi runtime. The parameters currently supported are as follows:

• Snapshot interval : The time interval in which periodic snapshots of the state is taken. Use 0 disables snapshots. This parameter enables the application to recover from server crashes.
• Distributed processing : Enable this to enable distributed processing

Imported streams

Contains mappings of imported (input) streams received from the event builder to the Siddhi runtime streams (defined inside query expressions). The parameters are as follows:

• StreamId : The stream id received from the event builder
• As : The name to be used when feeding the stream to the Siddhi engine. This can contain only alphabetical characters, numerics and underscore (_). 

Query expressions

This is where you can insert the queries written using Siddhi query language. You can define more than one query here, each ending with a semi colon. 

Exported streams

Defines how to map the streams exposed by the Siddhi runtime as outputs to the event formatter. The parameters are as follows:

• ValueOf : The name of the stream exposed by the Siddhi runtime. This can contain only alphabetical characters, numerics, '.' and underscore (_).
• StreamId : The name to use when exposing this stream to the event formatter. StreamId is of the format streamName:streamVersion. It can contain only alphabetical characters, numerics, and underscore (_). The stream version is of the format number.number.number (e.g., 1.0.0).