Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!auspex!guy
From: guy@auspex.UUCP (Guy Harris)
Newsgroups: comp.unix.questions
Subject: Re: fopen ( .., \"a\" ) --- how does the \"a\" work?
Message-ID: <2735@auspex.UUCP>
Date: 18 Dec 89 23:12:39 GMT
References: <21726@adm.BRL.MIL> <1989Dec14.045934.13669@chinet.chi.il.us>
Reply-To: guy@auspex.auspex.com (Guy Harris)
Organization: Auspex Systems, Santa Clara
Lines: 16

>Which means that it can't be guaranteed to know the current EOF position
>if there are multiple writers.

Correct.

>The server knows the EOF position, of course, but doesn't accept "append"
>requests.  With a stateless protocol the possibility would then exist for
>a request to succeed, but the ack back to the client to be lost resulting
>it a retry on the request.  If another "append" request intervened before
>the retry, the write would be duplicated in different places.

No, since the "write" request contains the position in the file at which
the "write" is to occur; instead, you run the risk of having your data
overwritten by another writer.  If the server *did* accept an "append"
request" that implicitly wrote to the end of the file, a retry would run
the risk of causing the write to be duplicated in different places.