How to create a workflow programmatically?

James,

You say that the sample "shows how to dynamiclly update a workflow instance", but this is not what I need; I need to create/modify a workflow definition, not the instance of a running workflow.

Alek

Using the designer assumes using an ActiveX control in the browser (assuming Web app). This is a valid -- and probably preferred -- approach for some scenarions, but unfortunately we cannot require this (what if a customer runs Linux?). So, considering not using the designer, there must be a way to define a workflow programmatically (and generate XOML definition, which we can then store in a database), at least this is what we were told at the TAP event, but I cannot find any samples or information how to do this. Actually, we have several teams looking for this feature, so we're a little stuck at this point.

Mark,

Thanks for the feedback. I checked the Simple Sequential Workflow sample, and if other samples use the same approach, this is not quite what I'm looking for. The sample contains the already programmed custom workflow class, and I am looking for a way to "create" a custom workflow class on the fly. Maybe I am not expressing myself correctly, but for some reason all the responses address the questions I did not ask. Just out of curiosity (so that I understand what I am saying wrong), why do you point to the explanation ot the serialization of the running workflow? I thought I mentioned several times that I do not care about changing workflow instances, I need to change the workflow definitions. Am I not using the right terminology? Should I phrase the question differently?

Regards,

Alek

Alek,
This post from Mark Schmidt might be of help somehow ?

Alek Davis:

It sounds like you want to build your own workflow authoring tool that doesn't use the Visual Workflow Designer control. Here's a code example that shows how to programmatically define a new Sequential Workflow with a single Delay activity and then saves it to a .xoml file. Then you can compile the .xoml file using the WorkflowCompiler class. Dharma Shukla posted an example of using the WorkflowCompiler class on his blog here.

// Create a new Sequentail Workflow SequentialWorkflow wf = new SequentialWorkflow(); wf.ID = "SequentialWorkflow1"; // Create a new Delay activity Delay delay1 = new Delay(); delay1.ID = "delay1"; delay1.TimeoutDuration = new TimeSpan(0, 0, 20); // Add the Delay activity to the workflow wf.Activities.Add(delay1); // Serialize the workflow to an XML file using the WorkflowMarkupSerializer System.IO.StreamWriter writer = new System.IO.StreamWriter(@"c:\temp\sequentialworkflow1.xml"); WorkflowMarkupSerializer serializer = new WorkflowMarkupSerializer(); serializer.Serialize(wf, writer); writer.Close();

I hope that helps.
James Conard
Architect Evangelist - Windows Workflow Foundation
http://www.WindowsWorkflow.net
http://blogs.msdn.com/jamescon

Hi Alek,

There indeed is a way to achieve what you are trying to do. You can create a workflow programmatically by using the workflow object model (which is the code that the VS designer generates in the .Designer.cs file in the background).

You can then save the workflow to a file as markup, and even compile the workflow programmatically. Our hands on labs(http://msdn.microsoft.com/workflow), specifically Lab 12 has an example of how to serialize a workflow as markup to a file. Check out the loader.cs file found in the completed lab. Here's a snippet showing the use of the markup serializer we provide:

StreamWriter writer = new StreamWriter(workflowMarkupFile);
try
{
WorkflowMarkupSerializer workflowMarkupSerializer = new WorkflowMarkupSerializer();
workflowMarkupSerializer.Serialize(workflow, writer);
}
finally
{
writer.Close();
}

Hope this helps!
Angel Azcarraga

Hi Alek,

I think I can clarify several things for you. So anytime you create an activity or a workflow through code, as in one of the examples above:

// Create a new Sequentail Workflow
SequentialWorkflow wf = new SequentialWorkflow();
wf.ID = "SequentialWorkflow1";

// Create a new Delay activity
Delay delay1 = new Delay();
delay1.ID = "delay1";
delay1.TimeoutDuration = new TimeSpan(0, 0, 20);

// Add the Delay activity to the workflow
wf.Activities.Add(delay1);

you're using the object model. If you're wondering how you specify order (left to right, up and down, etc.), it's basically like any other DOM (e.g. XML DOM). If you had children a,b,c to the children collection of an activity in the order b,c,a, then this is the order in which they will execute. The same case for activities with branches, etc. You are basically defining the structure with the order in which you add objects, and the parent/child relationships you give them.

If you want to see a good example of what the OM code looks like for a complex workflow, open the VS designer and create a workflow of your choice. Then open the .Designer.cs file and check out the code generated inside the InitializeComponent() method. This is precisely the code you want to create to define your workflow.

Please let me know if you need further details on this.

Thanks!
Angel