Re: [Libvir] RFC [1/3]: Re-factor QEMU daemon protocol to use XDR

First off we have the XDR definition file. This is basically a translation of the original qemud/protocol.h into the XDR format. The important changes are that - Instead of a single enum of message types there are now two enums - enum qemud_packet_client_data_type lists valid packets (ie method calls) that a client can make - enum qemud_packet_server_data_type lists valie packets (ie method replies) that a server can make There are two reasons for this split - This lets us add in more server packets which are not neccessaril method replies. ie async notifications ('domain foo start') - We use the enum to discriminate two unions later and there is actually already one type that's used by the server only QEMU_SERVER_PACKET_FAILURE to indicate a method which failed. - The big union qemud_packet_data is now split up - The inline per-message type structs are now all represented at the top level as fully named structs. - There is a qemud_packet_client_data union which is the union of all structs relevant to method calls - There is a qemud_packet_server_data union which is the union of all structs relevant to method replies - Introduce the idea of serial numbers. A serial number allows a client to track the incoming packet from the server which corresponds to a message it just sent. This is because in the future a server may be sending async notifications mixed inbetween method replies. So we have - A qemud_packet_client struct which contains a serial number & a qemud_packet_client_data struct. - A qemud_packet_server struct which contains a serial number, a replyto serial number & a qemud_packet_server_data struct. - Finally there is a qemud_packet_header which contains a magic 4 byte sequence and a length field. This is basically to make pulling the variable length XDR payloads off the wire easier to deal with. The header is always followed by a qemud_packet_client or qemud_packet_server XDR payload. The header length field gives the size of the payload. The magic byte sequence is just a sanity check, which is also useful in debugging. $ diffstat libvirt-qemu-xdr-protocol.patch Makefile.am | 15 + protocol.h | 329 -------------------------------- protocol.x | 608 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 620 insertions(+), 332 deletions(-) Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|