Dynamic Workflow Chaining (10.6.3)

For Stanford-School Of Medicine MediaFlow project we needed to chain Podcast Producer workflows dynamically,i.e. making calls to specified workflows from other workflows. This article describe how to reproduce this process (10.6.3)
Disclaimer: If you are not familiar with the command line,property lists and Podcast Producer workflows (e.g. pcastaction)you might find this article challenging, but then you probably won't have any interest for it anyway =)

Objective: Have a master_workflow.pwf call a second_workflow.pwf where second_workflow is choosen from a pool of existing workflows already uploaded in Podcast Producer Server.

A) master_workflow modifications
Edit the template.plist in the master_workflow bundle

 vi /path/to/master_workflow.pwf/Contents/Resources/template.plist 

This is the XML needed in your taskSpecification block in order to chain the workflows
caveats: --prb and --input are Apple provided Dynamic properties, be sure to understand what they point to.
Watchout for Task Dependencies (DependsOnTasks)

 taskSpecifications
		
			dynamic-submit-workflow
			
				arguments
				
					workflow
					--prb=$$GLOBAL::Library Bundle Path$$
					--input=$$Content File Name$$
					--workflow=$$workflow_1$$
					--user=PODCAST_USER
					--password=PASSWORD
				
				command
				/usr/bin/pcastaction
			
		

You also need to specify your property in the UserRequirements block. In this example it'd be:

 userRequirements
		
			workflow_1
		

Don't forget to upload/re-upload your modified master_workflow

 $ > pcast --installworkflow --path /Path/to/master_workflow.pwf [--overwrite] 

B) Generate a plist to use when submitting the file(s) to be processed by the chained workflows.
In our case we generate this file dynamically, hence the title of the article (doh!).

 vi /path/to/user_metadata.plist 

This is what you should have in your plist

  
       workflow_1
       NAME_OF_THE_WORKFLOW_AS_IT_APPEARS_IN_SERVER_ADMIN
 

Note that unlike the "podcast" command the "pcastaction workflow" command needs to be fed the podcast *name* and *not* its UUID.

C) Use the plist generated in B) to start your workflows chain with the podcast cli tool.
Note that unlike the pcastaction workflow command the podcast cli tool requires the workflow UUID.

 $ > pcast --submit --file /path/to/file/to/submit --workflow_uuid master_workflow_UUID --metadata /path/to/user_metadata.plist

Recommended Reading

Podcast Producer : Writing Actions
http://developer.apple.com/mac/articles/server/writingpodcastactions.html
Podcast Producer Administration
http://images.apple.com/server/macosx/docs/Podcast_Producer_Admin_v10.6.pdf
Notes
-We successfully chain 3 workflows but there is no reason why you shouldn't be able to chain more
-When in trouble check logs...including /Library/Logs/pcastserved/DiagnosticReports
-Watch your chained workflows progress in Xgrid Admin.
-To see the syntax and options to chain workflows

 $ > pcastaction help workflow