SObjectizer
It's all about in-process message dispatching!
...Since Aug 2019 the development of SObjectizer and so5extra is moved to GitHub:
https://github.com/Stiffstream/sobjectizer
https://github.com/Stiffstream/so5extra
SObjectizer is an in-process message dispatching framework with implementation of Actor Model, Publish-Subscribe Model and CSP-like channels.
SObjectizer allows the creation of a concurrent app as a set of agent-objects which interact with each other through asynchronous messages. It handles message dispatching and provides a working context for message processing. And allows to tune those things by supplying various ready-to-use dispatchers.