To step through the code of a custom pipeline component in real time in the Visual Studio debugger, simply do the following:
- Compile the component as Debug. Make sure you've got breakpoints appropriately set.
- Place both the DLL and the PDB file in the Pipeline Components folder (as with all pipeline components, you don't need to GAC anything).
- Configure a receive location/send port with a pipeline that uses the custom component.
- Open the component solution in Visual Studio, and in the Debug menu, select Attach to Process. Attach to the process that represents the host instance your port is running on (BizTalk services are named BTSNTSvc.exe. I don't know of any way to identify which one represents the host instance you want, if you have more than one running).
- Once attached, trigger the component by running a file through BizTalk.