I am not sure if you were implicitly stating it or not but maybe look at
keyed data queues instead of just data queues. That way your RPG program
can listen for a specific entry (read key). That would keep you from having
to loop on the RPG end. I may not be entirely understanding the entire
scenario though.
On the Java side I am curious to know if JavaFX (
http://sun.com/javafx) or
an "invisible to the user" applet could be employed to save repetitious
polling to the server. IMO, having a non-intrusive applet is acceptable in
a controlled environment (read intranet) - I actually expect to install
ActiveX objects or Applets for business process sites. Note that I have
done zero with JavaFX except for reading about it in SD Times (which is my
new favorite mag to read on the... the... well, you know where us guys read
about computers:-)
HTH,
Aaron Bartell
http://mowyourlawn.com
-----Original Message-----
From: rpg400-l-bounces+albartell=gmail.com@xxxxxxxxxxxx
[
mailto:rpg400-l-bounces+albartell=gmail.com@xxxxxxxxxxxx] On Behalf Of Paul
Holm
Sent: Friday, July 13, 2007 2:28 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: Server Initiated Design Alternatives
Hello,
We are building an RFID i5 Java based product where RFID readers populate
DB2/400 files as products pass into and out of "read zones".
We need both a JSP/HTML application and a RPG 5250 equivalent where we want
to continuously see new records/products as they are created and read
without having to manually push a refresh (or F5) button.
Basically the UI should continuously update showing new records. My
question is on design alternatives for both Java/JSP and RPG.
Alternative 1:
I know we could implement a "client" initiated "polling" approach where the
client continuously requests data from the server. From the Java side I
could use AJAX requests in a loop and from RPG use loop to reread or check a
data queue.
My concern with this approach is scalability because of the constant queries
that would be occurring in this mode.
Alternative 2: (Server to client push)
Anyone have experience or recommendations with a server to client design
approach? I'm hoping to not use sockets based server to client because of
the complexities and firewall/port issues.
I'm thinking an approach where a database operation would result in a
triggered data queue entry that could be "waited on". Once a data queue
entry is read, RPG could update its display. On the Java side, an AJAX
request could be waiting for the server to respond.
Advice, experience, or insight is appreciated before we go off on this task.
Thanks, Paul Holm
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