Re: [libvirt] [PATCH v2 01/12] Define keepalive protocol
On Fri, Sep 23, 2011 at 10:24:46AM +0200, Jiri Denemark wrote:
The keepalive program has three procedures: ADVERTISE, PING, and
PONG.
All are used only in asynchronous messages and the sender doesn't wait
for any reply. However, the party which receives PING messages is
supposed to react by sending PONG message the other party, but no
explicit binding between PING and PONG messages is made. ADVERTISE is
sent by a client to indicate it supports keepalive protocol. Server is
not allowed to send any keepalive message until it sees ADVERTISE.
I guess I'm not entirely understanding what the point of the
ADVERTISE message here is?
IIUC, the flow of messages you are describing will end up as:
1. C -> S remote_supports_feature_args (KEEPALIVE)
2. S -> C remote_supports_feature_ret (TRUE|FALSE)
3. C -> S keepalive ADVERTISE
4. C -> S keepalive PING
5. S -> C keepalive PONG
6. C -> S keepalive PING
7. S -> C keepalive PONG
...
n. C -> S keepalive PING
n+1. S -> C keepalive PONG
We need to the remote_supports_feature method to determine if the
keepalive protocol is supported, what purpose is the ADVERTISE
message serving ?
Regards,
Daniel
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