Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!ucsd!ucbvax!ORCAD2.dnet.ge.com!THIER
From: THIER@ORCAD2.dnet.ge.com
Newsgroups: comp.protocols.tcp-ip
Subject: Determining Socket Status
Message-ID: <9011062135.AA01288@ge-dab.GE.COM>
Date: 6 Nov 90 21:35:47 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 26


	I am implementing a UDP/TCP/IP communication software package 
for a small network of SPARCStation 1+'s running 4.1 and Motorola
MVME147 boards running VADSWorks. Message receive tasks are to be
kicked off using the asynchronous I/O mechanism.

	My approach is to utilize SIGIO to alert the receive processing
to socket activity, and then use SELECT and the associated mask
manipulation macros to identify the active sockets. What I haven't
figured out is how to determine the cause of a given SIGIO. Sun 
documentation states that the signal is posted upon state changes to
the socket. Fair enough, but how does one go about determining
which change (e.g, connection establishment/disestablishment, data
available in receive queue, etc.) has occurred? SELECT, I assume,
flags data availability, but a look at the socket state #defines 
(SS_NODREF, etc.) tells me that I need more than that to safely 
multiplex sockets. Is there a socket (or file) status call that I'm
missing? Thanks in advance.


John Thier
GE DSD
Pittsfield MA
thier@orcad2.dnet.ge.com