The Problem Solver

Today I ran into a annoying difference between XOML and code based workflows. In a project I have created a custom activity with a public property. I add this activity to a state workflow and add an IfElseActivity below it. Now I want to use the previously added activity property in the declarative rule condition.

In a code based state workflow I can type “this.myCustomActivity1.TestValue == True” into the rule condition editor. The editor indicates the expression is valid and compiling the project succeeds.

However when I do the same in a XOML with code separation state workflow things work differently. I can still add the custom activity and the IfElseActivity. The first time I try to use the custom activity in the rule condition editor the doesn’t show the this.myCustomActivity1. Adding a condition of true and compiling the project makes this.myCustomActivity1 visible in the rule condition editor. Now I can add “this.myCustomActivity1.TestValue == True” and the rule condition editor indicates everything is correct. However when I compile the project produces errors that the field "myCustomActivity1" on type "WorkflowConsoleApplication1.Workflow2" does not exist or is not accessible.

Now this is a bit of a PITA as it means creating a public property for every condition I need to test and there is little sense in creating a public property for a local test

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I have been a little frustrated in being unable to find a good solution for the following problem. If anyone has a good suggestion the feedback would be appreciated greatly.

Suppose I have a custom activity named CustomEventActivity that implements IEventActivity. The activity is used in a state workflow. This activity receives an event containing some data and saves this data so a second activity in the same EventDrivenActivity can check on the data. Something like:

protected override ActivityExecutionStatus

Execute(ActivityExecutionContext executionContext)

{

WorkflowQueuingService wqs =

 executionContext.GetService<WorkflowQueuingService>();

WorkflowQueue queue = wqs.GetWorkflowQueue(QueueName);

MyProperty = queue.Dequeue() as string;

return ActivityExecutionStatus.Closed;

}

Now I need to check on the data saved in MyProperty in a second activity in the same EventDrivenActivity. Beecause of the spawned context I can’t just use this.myCustomActivity1.MyProperty as this just returns the template activity with an empty property.

In a CodeActivity I can do something like:

EventDrivenActivity eventDriven;

CodeActivity code = sender as Activity;

eventDriven = code.Parent;

CustomEventActivity act1 = eventDriven.GetActivityByName(myCustomActivity1.QualifiedName, true) as CustomEventActivity;

Now this is cumbersome and error prone so I don’t like it

But things get worse if you want to use the value in a Declarative Rule Condition. Now it needs to be a single expression and we are located a little further inside the activity tree. I would need to use: ((CustomEventActivity)((Activity)sender).Parent.Parent.Parent.GetActivityByName(myCustomActivity1.QualifiedName, true)).MyProperty

Big yikes

Now I could just add a single property to the workflow and bind to that but in that case I would need to define extra properties on the workflow level that really have no purpose being there. Two additional problems:

1. If I want to use XAML workflows I would need to define the properties in base class, making it unusable when users want to expand the XAML workflow in a rehosted designer.
2. It is no longer possible to use a ReplicatorActity with ExecutionType is parallel. After all each parallel executing branch would point to the same activity.