Local Communication and Correlation Overview
Host processes can communicate with workflows by exchanging data through custom local communication services. These local communication services implement user-defined interfaces that define methods and events that will be passed between the workflow and the host process.
Host processes can also interact with a specific activity in a specific workflow instance by using a unique ID that is passed between the host process and the workflow as an event argument. This is known as correlation.
For more information about local communication and correlation, see Windows Workflow Foundation and Application Communication.