When you author a workflow in a declarative rules-based, code-free workflow editor, such as Office SharePoint Designer 2007, you are authoring that workflow directly against, and data-binding it to, a specific list or document library in Windows SharePoint Services 3.0. You are using a predefined list of workflow activities, and are not using any code. The workflow you design is not compiled as an assembly, but is stored as source files until Windows SharePoint Services 3.0 compiles the workflow the first time it runs.

This approach provides the following advantages:

• Workflows can be developed and tested rapidly.
• Because the workflow is specific to a given list, the following are simplified:
• The deployment process
• Security issues management
• Because workflows are not compiled into assemblies, workflows created in a declarative rules-based, code-free workflow editor such as Office SharePoint Designer 2007 can be deployed to servers where administrative policy prohibits custom code assemblies.

• Workflows can be created by users with less developer experience, such as Web designers or knowledge workers.

Because you author the workflow directly against and data-bind it to a document library, workflows authored in Office SharePoint Designer 2007 differ from those created using the Visual Studio 2005 Designer for Windows Workflow Foundation in the following important ways:

• You cannot deploy a workflow authored in Office SharePoint Designer 2007 to multiple lists. It is only valid for the list for which you created it.
• Because you are authoring the workflow directly against a list, the workflow is associated with the list at design time. Therefore, there is no association stage with workflows authored in Office SharePoint Designer 2007.
• You cannot modify workflows authored in Office SharePoint Designer 2007.
• You cannot author against a content type in Office SharePoint Designer 2007.

For a detailed comparison of Office SharePoint Designer 2007 and Visual Studio 2005 Designer for Windows Workflow Foundation, see Workflow Development Tools Comparison

Running Uncompiled Workflows

Because they contain no custom code, workflows authored in a declarative rules-based, code-free workflow editor such as Office SharePoint Designer 2007 are not compiled and deployed as assemblies. They are stored as their source files within Windows SharePoint Services 3.0, and only compiled into memory when needed.

For each site, the workflows of this type are stored in a separate document library. This document library contains a folder for each workflow authored in Office SharePoint Designer 2007. The folder contains all the source files necessary for the workflow, including the following:

• The workflow markup file
• The workflow rules file
• ASPX forms for any custom workflow forms that are needed

Windows SharePoint Services 3.0 includes a just-in-time compiler to compile the source files into a workflow the first time that workflow is started on an item. Windows SharePoint Services 3.0 retains the compiled workflow in memory until it is called again, much like servers caches compiled ASPX pages to speed execution performance the next time the page is called.

Each time a workflow is started on an item, Windows SharePoint Services 3.0 determines whether the workflow was deployed as an assembly or as source files. If a workflow assembly exists, Windows SharePoint Services 3.0 calls that assembly to create the workflow instance. If the workflow was deployed as source files, Windows SharePoint Services 3.0 next determines whether or not it already has a workflow compiled from those source files in memory. If it has, then Windows SharePoint Services 3.0 calls the in-memory complied workflow to create the workflow instance. If not, Windows SharePoint Services 3.0 uses its just-in-time compiler to compile the source files into an in-memory workflow, which it then calls to create the workflow instance.