This is most important for broadcasting. Associates an application with the according data server running on the same host. This request should be the first one received by a data server, and should be sent by the creator of the server. Request information, like available services, uptime, statistics etc. Request some computation on application side, and the results.
Possible parameters depend on thorn to be invoked.
Again, first get information about availability. Possible parameters depend on field type and visualization needs. This Request always refers to an ather, already handled one, and gives information about its handling. If request cannot be handled by anyone, an error has to be generated. The thorns themself have to parse the contents then, and do something according to its contents.