conductor-oss--conductor/docs/documentation/advanced/extend.md

description

description
Extend Conductor with custom persistence backends, queue implementations, and workflow status listeners for this open source workflow orchestration engine.

Extending Conductor

Backend

Conductor provides a pluggable backend. Supported implementations include Redis, PostgreSQL, MySQL, Cassandra, and SQLite.

There are 4 interfaces that need to be implemented for each backend:

//Store for workflow and task definitions
com.netflix.conductor.dao.MetadataDAO

//Store for workflow executions
com.netflix.conductor.dao.ExecutionDAO

//Index for workflow executions
com.netflix.conductor.dao.IndexDAO

//Queue provider for tasks
com.netflix.conductor.dao.QueueDAO

It is possible to mix and match different implementations for each of these.
For example, SQS for queueing and a relational store for others.

System Tasks

To create system tasks follow the steps below:

• Extend com.netflix.conductor.core.execution.tasks.WorkflowSystemTask
• Instantiate the new class as part of the startup (eager singleton)
• Implement the TaskMapper interface

Workflow Status Listener

To provide a notification mechanism upon completion/termination of workflows:

• Implement the WorkflowStatusListener interface
• This can be configured to plugin custom notification/eventing upon workflows reaching a terminal state.

Event Handling

Provide the implementation of EventQueueProvider.

E.g. SQS Queue Provider: SQSEventQueueProvider.java