To access services provided by the new component. In case of jBPM, it is represented by various services provided by jBPM, for example, the process runtime provision for managing the life cycle of a business process. JBPM exposes these services as APIs of its core engine.
To enable jBPM to access the services provided by other components in the application architecture. The extension points that JBPM provides for integration with external components are the workitem handlers. We can create handlers and write the logic for accessing the external components.
The following figure depicts this context: