RE: AS/400 IP COMMUNICATION WAIT TIME

Jim,

You've got it mostly right.  Except the part about TCP being "Connection
Based".  It does not have to be that way.  Look at HTTP.  The connection is
not maintained for the duration of the session.  Only while data is being
exchanged.  Other protocols/applications are different.  Telnet is
connection based.  FTP is actually both.  The control part of the
conversation is connection based, but data is exchanged over a
connectionless conversation.  And custom applications can be how ever you
want them.

The main difference between TCP & UDP is that when you send data via TCP, it
is guaranteed to not only arrive at the destination (or cause an error) but
also in the same order you send it.

When you send with UDP, not only is the data NOT guaranteed to arrive at the
destination, but the data MIGHT be out of order.  As a result, UDP tends to
be used for "trivial" things (like ping) or broadcast where each byte of
data is not that important (streaming sound/video).

Bob

-----Original Message-----
From: owner-midrange-l@midrange.com [mailto:owner-midrange-l@midrange.com]On
Behalf Of Jim Langston
Sent: Thursday, January 06, 2000 6:13 PM
To: MIDRANGE-L@midrange.com
Subject: Re: AS/400 IP COMMUNICATION WAIT TIME

Short answer: it is not possible to disconnect without the clients
"knowing".

Long answer:
TCP is a connection scheme.  When using TCP/IP the connection
remains open.  Once the communication between the server and
the client is closed, the TCP/IP connection is closed.  UDP, on
the other hand, is a broadcast scheme.  There is no permanent
connection.

Since the majority of IP communication is TCP based (including
client access and the like) if you disconnect the cable from either
the server or the client the channel is closed, and the program
errors out, either graceful with a window saying the session has
been terminated, or ungraceful for programs not looking for this.

Once you disconnected and reconnected, the connections would
have to be re-established.

Regards,

Jim Langston

oludare wrote:

> Hi Guys, I need to know.  Is it possible to disconnect the RJ45 that
> connects all CLIENTS (PCs) to the AS/400 box, communicating over IP,
> and reconnect back without any CLIENT knowing that communication was
> interrupted.  What happen to all active interactive jobs (programs)
> from the PCs and Session Manager? Thanks for you help. Oludare

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