Re: ILE RPG SOCKET PROTOTYPES -- MIDRANGE-L



Hi David ,

On the server side when a socket  server is brought up ,the three initial
steps which are done are BIND(), LISTEN(), and ACCEPT() . So I thought I
will do all these three steps in the same procedure , so that the user has
to call only one procedure to get a server up . On the client side a socket
application won't need to these steps.(BIND( ) is optional on the client
side ) .

As the server accepts a client connection request it creates a new socket
descriptor for the client (in my example it is clnSd) .
This is the socket which is used to communicate with the client (send and
receive) . The original socket on which the server listens (retSd in my
example) is kept open to listen to new requests .

So if you want to spawn a new job for each client  you accept , you have to
pass the socket descriptor for that client (clnSd) to the child job . So
the main server job has to do a givedescriptor( ) and the child job has to
do a  takedescrpitor( ) .

I have a small program which does this . How it works is , while spawning a
new job (doing a SBMJOB) the main job passes the internal job identifier of
the main job as a parameter . As the child job gets active it writes its
own job identifier to a dataq on which the main job is waiting . The main
job after getting the child job's internal job identifier  does a
givedescriptor( ) to pass the socket descriptor (clnSd) . The main job has
to wait till the child job is active , because you can not give a
descriptor if the other job is not active . In the child job after writing
that entry to the dataq , the child job waits on a takedescrpitor( ) .
After it gets the socket descriptor from takedescrpitor( ) it is
independent of the main job and communicate with the client . This is not a
very efficient way to do this because , if child job takes a while to get
active , the server job is waiting on the dataq indefinitely . But we can
have a  wait time for the dataq and come back to it in intervals if we
don't get anything from it in the first read .

Hope this helps.

Thanks

-Amit







David Anderson <DaveTheWiz@worldnet.att.net> on 08/17/99 08:15:38 PM

Please respond to MIDRANGE-L@midrange.com

To:   MIDRANGE-L@midrange.com
cc:    (bcc: Amit Mukherjee/SMS)

Subject:  Re: ILE RPG SOCKET PROTOTYPES




Amit,

I read your article, and it was very helpful in learning sockets and ILE
RPG.
I'm glad you subscribe to the list, because I wanted to ask you why, in
your
article, you combined the BIND(), LISTEN(), and ACCEPT(), into 1 bind_tcp
prototype?

Say I have a Socket Server running (not literally):

     Server issues open, set socket options, bind, and listen.
     When a connection is issued against this server, doesn't it then do an
accept
to start a
     conversation with that job on a new socket from the accept?

     Once the accept is completed, do you know an easy way, or even not so
easy,
if you've already
     got the code, to go through the process of submitting a client job,
doing the
give and take descriptor
     thing to hand off the conversation, and then going back to listen on
the
original socket?

     That is also one of the things that I want to do.

What I am actually trying to do is set up sockets so that files can be sent
from
an AS/400 to:
     Other AS/400's
     RS/6000's
     SCO Unix
     IBM MVS Systems

Right now I use FTP to send the files, and it works pretty good, but what a
pain
reading through output logs to see if the
transmission completed normally.

Sorry I got a little long winded, but this is a learning process for me and
any
help is greatly appreciated.

Dave Anderson
SYSCO Food Services of Los Angeles, Inc


Amit.Mukherjee@smed.com wrote:

 > There was an aricle of mine in the News/400 June99 issue  about sockets
 > with a service program having prototypes for most of the socket
functions a
 > socket application will need . The code is available at the news400
site.
 >
 > Thanks
 >
 > -Amit
 >
 > "Nelson C. Smith" <ncsmith@gate.net> on 08/13/99 07:51:56 PM
 >
 > Please respond to MIDRANGE-L@midrange.com
 >
 > To:   MIDRANGE-L@midrange.com
 > cc:    (bcc: Amit Mukherjee/SMS)
 >
 > Subject:  Re: ILE RPG SOCKET PROTOTYPES
 >
 > -----Original Message-----
 > From: David Anderson <DaveTheWiz@worldnet.att.net>
 > To: MIDRANGE-L@midrange.com <MIDRANGE-L@midrange.com>
 > Date: Friday, August 13, 1999 2:54 AM
 > Subject: ILE RPG SOCKET PROTOTYPES
 >
 > >Does anyone have a working example of socket prototypes for
 > >    send_file and accept_and_receive.
 > >
 > >I would rather send an entire file with one API call.
 > >
 > >I've already tried to use the links in the manual OS/400 Sockets
 > >Programming V4R3, but where the tell you to go doesn't exist.  I don't
 > >mind doing it myself, so if
 > >someone could point me in the right direction I'd appreciate it.
 > >
 > >Thanks in advance,
 > >
 > >Dave Anderson
 > >Sr. Programmer/Analyst
 > >SYSCO Food Services of Los Angeles
 >
 > Why do we have to do it ourselves all over again if someone already has
it
 > working good?  That's why we need those shareware sites that have been
 > talked about here before.
 >
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