The OCFA inter process messaging library

The message library offers the facilities to communicate simple short messages between processes within the open computer forensics architecture. In a normal configuration any normal module including those within OcfaArch is configured as a messaging client, and the anycast relay is configured as a messaging server. Basically all clients connect to a single server that acts as a relay between addressable nodes (module instances). Messages sent between the processes can be of the following types:

Unicast messages : messages directed at a specific module instance.
Broadcast messages: messages directed at all connected modules.
Anycast messages: messages directed at 'any' instances of a specific module type.
Multicast messages: messages directed at all modules that are subscribes to a specific channel.

Normal modules will use Anycast messaging to communicate evidence data and metadata with other modules. Special messages like ocfahalt will be sent using Broadcast or Multicast. A special process called the anycast relay is able to turn anycast messages into unicast messages for specific module instances. By using anycasts, a distributed environment can be built where multiple instances of a particular module can be run on different computers. The anycast will take care of the load balancing, buffering and addresses the reliability.