RE: Client/Server Applications - what to use?

["Gary R. Patterson" <midrange-l@xxxxxxxxxxxxx>]

I think the "best" way depends on data volume and number of users.  For low
volume applications where response time and throughput are not essential,
xDO is easy.  Our experience has been that as volume increases, application
performance degrades.  Maybe recent releases are better.

Data queues are pretty fast and lightweight, but not portable.

We use sockets.

Here is how we structure our applications:

1) User interface in VB.
2) Cosmetic data validation in VB (anything not requiring database access -
to save the round trip to the host system).
3) Pass request to sockets-aware host server program (ILE RPG - clients
never have the C compiler).
4) Modular host programs/procedures perform database-based validations and
encapsulate complex business logic.
5) Host programs/procedures returns results or error information to VB
client program.

Benefits:
1) Fast - Sockets perform very well.
2) Lightweight - No ODBC/xDO/JDBC/SQL overhead at either end.
3) Portable - We can create clients on any platform that supports the
sockets API.  Easy to connect from Java, C, VB.  Easy to develop web-based
clients via ASP, Java servlets, even from CGI programs.

Just FYI:  We are kicking around moving to DB2/400 trigger programs for
centralized/standardized data validation and business rules.  Our host
socket programs get simpler - they just do an add/update/delete to the
database, and trap for an error, rather than implementing data validation
themselves.  We will still do redundant cosmetic data validation at the
client for performance reasons.

Has anyone else been down this road and made a different decision?  I would
be interested.

Gary R. Patterson
NexSource, Inc.
www.nexsource.com

-----Original Message-----
From: owner-midrange-l@midrange.com
[mailto:owner-midrange-l@midrange.com]On Behalf Of Iain Clark
Sent: Wednesday, August 30, 2000 1:08 AM
To: 'MIDRANGE-L@midrange.com'
Subject: Client/Server Applications - what to use?


I have an application to write that I feel would benefit from a graphical,
ie VB5 front end. My question is - what is the best way to link the
application to the as/400....APPC, Data Queues, RDO/VDO, ODBC, etc, etc.
There would need to be a certain amount of validation to be performed on
various input fields, so constant communication between the two is
imperative.  Any ideas or pointers would be appreciated.

Regards
Iain

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