Organic groups and Workflow How can I create a separated workflow for a content type like "Article" for each organic group?

For example:


"Math Group" has the roles "Author," "Head."
"Article" nodes created by users with the "Author" role in "Math Group" will be visible only by users with the role "Head."
Users with the "Head" role will review "Article" nodes, and then publish it or send it back to "Author" for improvement.


How can I implement it with OG and Workflow?
You create a workflow state called "review" and set it so it is only accessible by Head users. Also set the states so any author can only put workflows into this "review" state - only Head users can actually change this to other workflow states. 

So, the Head role can access the Workflow summary in order to review all the article group nodes which have been created in the review state.

If the Head approves it, he can change the workflow state to published which is accessible to all.

If the Head denies, he can change the workflow state to Needs work, which will mean the content remains unpublished.

If you want this to go back to the original author you can set this up with an email using actions / triggers or use the rules module.