What Is an Activity Assembly

What Is an Activity Assembly-

An activity assembly is a compiled .NET assembly (.DLL or .EXE) that contains one or more workflow activities. These activities are reusable units of work that form the building blocks of a workflow application.

 What’s Inside an Activity Assembly?

Typically, an activity assembly includes:

  • Custom activity classes: These inherit from System.Activities.Activity (WF 4.x) or System.Workflow.ComponentModel.Activity (WF 3.x).
  • Business logic for each activity (written in C#, VB.NET, etc.).
  • Metadata for tooling and design-time support (optional).
  • XAML files (in case of declarative workflows or activities).

 Use Cases-

You would create an activity assembly when:

  • You are building custom reusable workflow activities.
  • You want to separate workflow logic into modular components.
  • You’re sharing workflow components across multiple projects or teams.
  • You want to create pluggable activity libraries for your workflows.

 How It’s Used

  1. Compile the activity code into a .DLL.
  2. Reference the .DLL in a workflow project.
  3. Use the custom activity in a workflow, either in code or XAML.

 Benefits of Activity Assemblies

  • Reusability: Share custom logic across workflows.
  • Encapsulation: Keep activity logic modular and clean.
  • Maintainability: Easier to update, test, and manage.
  • Design-time support: Show up in tools like Visual Studio Designer if properly attributed.
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