Windows Workflow Services - What are they?

Question

I'm just beginning to learn Windows Workflow and am working through a book on the subject. I've seen several references to something called Workflow services. For example, the Model Service is one of them. What I haven't seen is a very good explanation as to what these services really are. Can someone help me with this?

Answer 1

EditingContext Services are a set of services used by workflow designer hosting environment. They can provide very usefull information and functionality of your workflow designer. You are able to inject your service implementation to change a behavior, get information or be notified about designer changes.

Some examples on services and a brief explanation of each one:

• IDesignerDebugView - Controls breakpoints, debug state, and source locations for debugging
• IExpressionEditorService - Creates expression editors that can provide intellisense on Visual Studio(using .net VB stuff) and in rehosted scenarios.
• IValidationErrorService - Used to show workflow validation messages in custom controls
• ModelService - Raise events on designer changes, get workflow root and find itens. See more here

See this link for complete list of EditingContext services:

Answer 2

A Workflow service is a WCF service implemented using a WF4 workflow. It typically starts with a Receive activity that is triggered when a SOAP message is received. When the workflow is ready to send a response to the client a SendReply activity is used. However the workflow is free to keep on running and can receive more events later on in its life.