Tuesday, September 16, 2008

Metastorm BPM 7.6 and Windows Workflow part 4 - Using your own activities

My previous posts on Metastorm/WF integration have had a few comments, so I thought I'd follow up on them.

First up, it is possible to reference your own assemblies containing custom activities in the WF Composer, via the Options dialog that can be found on the main menu. For me this means the Composer could potentially be used by non-technical people, although the workflow designer may still be too difficult to hand over to non-techies (this isn't Metastorm's fault BTW, the design surface is all Microsoft's work).

But before I could check out this feature, I had a problem using the Composer. I haven't used it for a few weeks or months and when I tried to do almost anything I got the following error

Could not load file or assembly 'mscorcfg, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified. (mscorlib) 

I suspect this is down to me uninstalling Visual Studio 2005 since I installed the WF Composer which I guess uninstalled the .NET 2.0 SDK which is required by the WF Composer. It's a shame the SDK is required, as it's a 354MB download... If it's just for the one assembly then it's flipping ridiculous.

Anyway, after installing the SDK and reinstalling the Metastorm WF bits, things started working again (the re-install may not be necessary but I uninstalled before I realised what my problem was).

OK, so I thought I'd try to use some of my own activities. My first problem was that any assembly I tried to reference produced the following error

No toolbox items found in assembly!

This was easily solved by adding the following attribute to my activity class definition


My activities now appear in the toolbox but I'm unable to drag them onto the design surface. I guess I'm missing something in my activity class code but I don't know what. They work in Visual Studio and my own designer so I'm not sure why they fail here. Anyway, although the WF Composer is of passing interest, my main interest is using workflows authored in Visual Studio, so I'm not going to look at it too closely.

Part 1 - The basics

Part 2 - The database tables

Part 3 - Using Visual Studio

Part 5 - Long running workflows

Part 6 - State machines

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