peterson@SW.MCC.COM (James Peterson) (09/13/88)
At the Protocol level, I can generate Requests which expect replies. A Reply identifies the request that it is a reply to by its sequence number. I can generate many requests before waiting for the replies. Since the format of a reply depends upon the type of request that was made, I must keep a list of all outstanding requests, their sequence numbers and the type of the reply. If a Request generates an Error, the Error identifies the Request by its sequence number. Is it always the case that if a Request expects a Reply, and an Error is received for the sequence number of that Request, then there will be no Reply? That is, I can remove the sequence number from my list of pending replies if I get either the expected reply or an Error. Also, I notice that Events have sequence numbers, but can find nothing in the Protocol document explaining what they are for. jim
swick@ATHENA.MIT.EDU (Ralph R. Swick) (09/13/88)
Date: Mon, 12 Sep 88 12:17:12 CDT
From: James Peterson <peterson%sw.MCC.COM@mcc.com>
Is it always the case that if a Request expects a Reply, and an
Error is received for the sequence number of that Request, then
there will be no Reply?
Yes. Section 5. Errors:
"In general, when a request terminates with an error, the request has
no side effects (that is, there is no partial execution). The only
requests for which this is not true are [a list of requests, none of
which generate replies]."