Editing Cfengine3 Messaging (section)

== Nodes sharing information ==
Information sharing nodes need a method that enables them to send the information they are willing to share. In the analysis use cases of types of messages have to be mapped on the basic patterns. The listeners mirror the nodes mappings.
Nodes carry different kinds of information
* Common information
* Static information
* Dynamic Information
* State Information
In the current design of CFEngine the cf-agent then has to be extended with a promise type: messages:<br/><br/>
It goes withoout saying that messaging needs authentication and autorization mechanisms.
 == Messaging and Data ==
Convergence is one of the key concepts of CFEngine and The CFEngine Roadshow is designed to convergently work towards the desired state.<br/>
=== ZMQ ===
The CFEngine Roadshow is able to apply a light weight broker less messaging system, ZeroMQ, because the information from the agent will eventually arrive. So far the Data use case only applies Asynchronous Request/Response.<br/>
Other agent in other roles are free to implement their own message exchange systems.
=== Data ===
The REQ message arrives at Data in a JSON format and Data stores the message in the feeds schema in the database, for processing, using the JSONB data type. JSON stands for JavaScript Object Notation, JSONB stands for JSON Binary.<br/>
Data runs a Python3 Object Oriented application. Data responds with a tailor made response with all the external data the host needs to configure itself.<br/>
Data delivers the data in a leveled structure:
* host 
* domain
* role
* host_role
* domain_role