1 Here are some elements of specification of the GRAS protocol. It is not
2 supposed to have several implementations, but once version 1 will be out,
3 all versions of GRAS are supposed to be able to communicate with previous
6 All messages have an header and a payload. Here is the header format,
7 considering it as an array of chars.
9 HEADER: Transport layer
10 msg[0...3]: the string 'GRAS'
11 msg[4]: protocol version (currently '0')
13 HEADER: Messaging layer
15 msg[5]: discriminent = Archi & msg type & Flags
16 D & 248 << 3 : archi (datasize, alignment, endianess) of message emitter
17 (32 possibles; 5 known so far)
18 D & 7 : Type of message:
20 1: method call (answer expected)
22 2: successful return (usual datatype attached as payload)
23 3: error return (payload = remoterr)
25 4..7: idem, with group communication (ask for forward)
26 list of receivers (and path for answer) placed before the
29 msg[6..8]: message serial (for answers; omitted for one-ways)
30 short in binary encoding (loop every 65536)
31 msg[9..]: message name (string in the binary encoding)
33 PAYLOAD: in the binary encoding