Module Architecture
As the figure shows, the framework consists of several units: the ZMFCore, which encapsulates the main functionality of the framework such as starting and stopping of modules. Also it provides an interface that modules can use for accessing the framework and for connecting to other modules through it. These modules are always derived from the AbstractModule-class.
Furthermore, the ZMFCore controls the execution of two more essential services that are started and stopped with an instance of the ZMF. The first is called the PeerDiscoveryService which subscribes to a multicast group in the network to which all other ZMF instances also subscribe. The service frequently sends out so called heartbeats in form of udp-multicast messages. This way every instance of the ZMF knows about all other module instances that are available at this time and what state the currently have.
The ZMQMessagingService provides functionality to modules that can be used for sending direct ZMQ request messages to other modules and for receiving their replies in the same way. It can also be used to publish ZMQ messages to a certain topic or to receive messages from other modules through a preceding subscription to this topic.
Module applications call the run method of the ZMF framework (eg. from the main method) to start the ZMF instance.
For further information about ZMF see ZMF Wiki.