Server to Client Design Approaches

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