EnumerateResourcesActivity - the follow-up

November 16, 2009 at 10:13 PMHenrik Nilsson

A couple of months ago Joe Zamora (the CShark) was trying to solve the mysteries around the EnumerateResourcesActivity, a great activity that you could use from your own custom activities/workflows but not from the FIM workflow designer, read Joe’s post here. After a lot of work, some help from Nima in the product team and a couple of not that useful tips from me Joe got it working. See the forum post where me and Joe was trying to accomplish this here.

The EnumerateResourcesActivity is the only activity that could search for and return resources in FIM and it does so simply by you giving it an XPath query. It’s a really nice activity except it’s got limitations in that it can only contain a single child activity (actually not strange at all, the same goes for the ReplicatorActivity) and it has a got a designer that doesn’t allow for adding the child activity declaratively so you’re forced to add the single child using code. The EnumerateResourcesActivity work pretty much as the ReplicatorActivity in that it iterates bunch of values only in the case of the EnumerateResourcesActivity it finds the values (resources) before iterating them. An important aspect of workflow crafting is that an activity can’t be executed twice and that is handled by the EnumerateResourcesActivity by creating duplicates of the child activity objects (and descendant objects of the child activity) for each iteration before the iteration is started therefore you can’t use the original activity object references for getting activities within the iterations.

Joe used a CodeActivity as the single child but the solution I’m going to show you will use a SequenceActivity instead making it possible to add more than one single activity because you will probably want to do work suited for other activities like add a user to the group you have found or something like that.

I won’t go through all the stuff around activity crafting, for this you’ll have to turn to the Windows Workflow Foundation developer center , the Forefront Identity Manager 2010 Developer Reference or maybe the oracle scrapheap's named Google and Bing. First of all we need some code in the designer part of our custom Activity class (A custom activity is usually created from two partial classes when you create it in Visual Studio). In the InitializeComponent method I create a EnumerateResourcesActivity, add a SequenceActivity to it and to the SequenceActivity I add a CodeActivity but I leave for you to create more child activities to the SequenceActivity after the CodeActivity. Finally I add the EnumerateResourcesActivity to the custom activity I’m currently creating:

private void InitializeComponent()
{
    this.CanModifyActivities = true;

    // codeActivity
    this.codeActivity = new CodeActivity();
    this.codeActivity.ExecuteCode += new System.EventHandler(this.codeActivity_ExecuteCode);

    // sequenceActivity
    this.sequenceActivity = new SequenceActivity();
    this.sequenceActivity.Activities.Add(this.codeActivity);

    // enumResourcesActivity 
    this.enumResourcesActivity = new Microsoft.ResourceManagement.Workflow.Activities.EnumerateResourcesActivity();
    this.enumResourcesActivity.PageSize = 100;
    this.enumResourcesActivity.XPathFilter = "/Person";
    this.enumResourcesActivity.Activities.Add(this.sequenceActivity);
            
    // MyCustomActivity
    this.Activities.Add(this.enumResourcesActivity);
    this.Name = "MyCustomActivity";

    this.CanModifyActivities = false;
}

Did you notice the XPathFilter property of the EnumerateResourcesActivity that I’ve set to return all person objects? You might think it’s strange that I add a CodeActivity as the only child of the SequenceActivity but I use this for getting the resource for the current iteration and it also gives a method that you could use for assigning values to siblings further down the execution chain from the CodeActivity that I leave up to you to add.

Here’s how I extract the value from the EnumerateResourcesActivity:

void codeActivity_ExecuteCode(object sender, EventArgs e)
{
    SequenceActivity s = (SequenceActivity)((CodeActivity)sender).Parent;
    ResourceType resource = EnumerateResourcesActivity.GetCurrentIterationItem(s) as ResourceType;

    // Perform initialization of any sibling activities here but remember you must reference
// them as I’ve done above with the SequenceActivity
// and a good way of doing it could be for example...
// UpdateResourceActivity u = s.Activities.OfType<UpdateResourceActivity>().First();
// or other generic “queries”.
}

First of all we need to get the SequenceActivity of the current iteration and since we know it’s the parent of the CodeActivity we could get the Parent property object of the current CodeActivity object instance that we’ve got from the sender parameter. Then we call the static GetCurrentIterationItem method passing in the SequenceActivity object instance and this should return the resource for the current iteration.

Next I leave up to you to use the values of the found resources to do whatever you wish and that could be for example update the resources found, delete the resources found or maybe create new resources from whatever values the found resources contain.

Posted in: Forefront Identity Manager | Identity Management | Workflow

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