Newsgroups: comp.parallel.pvm
From: Jonathan King <jking@cv.hp.com>
Subject: Re: [Q] sending empty messages
Organization: Hewlett-Packard Co.
Date: Fri, 02 Aug 1996 11:36:00 -0700
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Message-ID: <32024A90.1EE8@cv.hp.com>

Axel Spohr wrote:
> 
> I hope one of you can help me on the following:
> Can I send empty messages with pvm ? The receiving task only
> needs to know the message tag of the incoming message. Will pvm
> complain or just drop the empty buffer ?
> 
> An example would look like:
> 
>         call pvmfinitsend(encoding,buffer)
>         call pvmfsend(tid,messagetag,info)
> 
> where messagetag contains an integer value needed by the task
> identified with tid.
> Any ideas ?
> TIA

Yes, this is possible.  However, it may just be easier (coding wise) to
pack an integer... otherwise you have to receive any message and then
get the buffer info to figure out what tag the message had.  If you want
to receive only a subset of messages from that host, you can't do it. 
You're paying the overhead for communication anyway, the price to pack,
send, and unpack another int is negligible.  If anyone knows a faster
way to figure out what the tag was, will you let me know?  Thanks.

Jon

-- 
#######################################################
# Jonathan B. King        kingjo@research.cs.orst.edu #
# M.S. Student in C.S.    jking@cv.hp.com             #
#                                                     # 
#   My opinions are my own and do not represent the   #
#      views of either Hewlett Packard *or* OSU.      #
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