Re: Server to Client Design Approaches

[Jim Blizard <jblizard@xxxxxxxxxxxxxxxx>]

A Java applet (or Adobe Flex 2 application) with an IP connection to the 
server and and a DB2 trigger when a row is updated/inserted should do 
the trick.

Jim Blizard

Paul Holm wrote:
> Hello, (I also posted on RPG list since it involves both languages)
>
> 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
>
>