I’ll get straight to the point:
I was wondering if there is a common pattern to use portable areas as a components of a plugin-like architecture.

Example:
We’ve got 3 plugins (portable areas) packaged and distributed via NuGet feed.
Each of them is following the standard MVC structure (has it own Models, Views and Controllers). Lets say login form, header and footer.

What I was wondering if there is a way to make them communicate.
For example: when user logs on, login plugin executes it own logic, logs the user and then it updates the state of the header plugin with changes it state accordingly.

Edit: Dealing with client side calls
Another thing that I did not mention in the original post is that I wanted to expose the plugin features via controllers to be consumed via JavaScript as well.
Lets say I have all architecture in place and all plugins registered themselves with the system properly (routes, dependencies …etc)
For example if I click the “Change color” feature of one “Colors picker” plugin it calls action method of another plugin (Image plugin lets say) and loads image of requested color. Of course everything should be done via Ajax without resubmitting the entire page that hosts the components.

You think it is a doable scenario in the solutions you’ve proposed here?

Thanks in advance for all the answers.