Creating a STORM Based Distributed Execution Plan

WSO2 DAS uses storm based distributed execution plan to store the processing logic to be used in a distributed mode deployment.

Writing an execution plan

The procedure for creating an execution plan is the same as that in Creating a Standalone Execution Plan. In addition, the following annotations are used in the Siddhi queries.

Annotation	Description	Example
`@dist (parallel='<number of Storm tasks>)`	The number of storm tasks in which the query should be run parallel.	`@dist(parallel='4')`
`@dist(execGroup='name of the group')`	All the Siddhi queries in a particular execGroup will be executed in a single Siddhi bolt.	`@dist(execGroup='Filtering')`
`@Plan:dist(receiverParallelism='number of receiver spouts')`	The number of event receiver spouts to be spawned for the Storm topology.	`@Plan:dist(receiverParallelism='1')`
`@Plan:dist(receiverParallelism='number of publisher spouts')`	The number of event publisher spouts to be spawned for the Storm topology.	`@Plan:dist(publisherParallelism='4')`

The following execution plan is populated with the above mentioned annotations.

Once an execution plan is created as saved, its configuration in WSO2 Siddhi Query Language format is saved in the <DAS_HOME>/repository/deployment/server/executionplans directory.

Note:
Every Siddhi query in a particular execGroup should have the same number of tasks as shown in the execution plan above ( e.g., parallel = '4' ). If the queries need to be distributed across different siddhi bolts, the execGroup names of the queries should differ from each other.