Re: [9fans] 9p2000 query

[I RATTAN <rattan@cps.cmich.edu>]

Here is rephrasing:

server process om machine X is servicing tokens to clients (run on
other machines):

client on A sends a request (message), wsits for reply to come back
can server process pickup the request with single read operation
(assume that a connection has been set up between client and
server processes)?

scenarios possible here:
- one can use tcp from tcp/ip (it is there under Plan 9)
- one can use udp from tcp/ip (is it available under Plan 9)
- one can use 9P without worrying about the underlying protocol(s)
  as it will provide guaranteed service??

-ishwar

On Fri, 13 May 2005, andrey mirtchovski wrote:

> > or no, depending on the file server.
> > it's not really a well-formed question now that i think about it.
> >
> > devpipe preserves message boundaries.
> > il does too.
> > tcp does not.
> >
>
> "Plan 9 from Bell Labs" discusses message boundaries briefly in the
> context of 9p:
>
> "The 9P protocol must run above a reliable transport protocol with
> delimited messages.  9P has no mechanism to recover from transmission
> errors and the system assumes that each read from a communication
> channel will return a single 9P message; it does not parse the data
> stream to discover message boundaries.  Pipes and some network
> protocols already have these properties but the standard IP protocols
> do not.  TCP does not delimit messages, while UDP [RFC768] does not
> provide reliable in-order delivery."
>
> those may not be the same message boundaries Ishwar was looking for
> though.
>