RE: Bob's letter on V5R4 RPG stuff

Interesting stuff.  I specifically was interested in the XML added value!
It is very interesting to me that this got added as a language feature over
the hundreds of other things that could have been done (I would have loved
having overloading of sub procedures first, and then the ability to define
custom ON-ERROR types :-)

Can anybody elaborate on the path=xmlnode/name feature of the %XML bif?  It
is mentioned that SAX is being used, but the path feature leads me to
believe that there is DOM functionality involved also which wasn't directly
mentioned (not that it needs to be I guess). DOM leans toward the entire
document being loaded into memory and the programmer picks what values it
wants out of the document when they want them vs. doing the SAX event driven
model with call-backs.

While the DOM approach is much more appealing to the ease of programming, I
don't know how well it would scale in a large XML capacity environment
(which is what IBM's SOA initiative is calling for).  When I started out
parsing XML I leaned heavily towards DOM because I didn't understand
call-backs and the events that took place during the parsing of a XML
document, but now that I know how they work I feel it is a much better
approach for performance sake.  Thoughts?

The other thing that would be interesting to know is how they go the DOM
route with repeating structures.  When I wrote my first interface over IBM's
XML4PR400 API set I made the programmer accept a pointer return value when
they wanted to access a list of entries (i.e. /Order/LineItemList) and then
they would use that pointer to get each iteration of the items within
"LineItemList".  The only way I envisioned being able to easily access
repeating structures with the DOM approach would be to have something
similar to he following:

/free
count = DOM_getNodeCount(parserObject: '/Order/LineItemList/Item');
for i=1 to count by 1;
  itemConent = DOM_getNodeValue(parserObject: '/Order/LineItemList/Item(i)':
i);
endfor;
/end-free

.. And then what happens if you have multiple structures repeating within
structures. Then you could code something like this:

/free
count1 = DOM_getNodeCount(parserObject: '/Order/LineItemList/Item');
count2 = DOM_getNodeCount(parserObject: '/Order/LineItemList/Item/Price');
for i=1 to count1 by 1;
  itemConent[i] = DOM_getNodeValue(parserObject:
'/Order/LineItemList/Item(i)': i);

  for x=1 to count2 by 1;
    priceConent[x] = DOM_getNodeValue(parserObject:
'/Order/LineItemList/Item(i)/Price(x)': i: x);
  endfor;
endfor;
/end-free

The other thing I am wondering about is how these allow for SOAP processing
and getting the encoded content into XML form so it can be parsed. This is
important because 90% (a very guestimate number) of .NET and Java web
services are going to pump out SOAP web services or expect to consume SOAP
web services. That is just a guess based on my dealings with .NET and Java
programmers in the past year or so.

Very exciting to say the least!!

Aaron Bartell
http://mowyourlawn.com/blog


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of rob@xxxxxxxxx
Sent: Wednesday, February 01, 2006 8:19 AM
To: rpg400-l@xxxxxxxxxxxx
Subject: Bob's letter on V5R4 RPG stuff

Just in case it's bad form for him to post his own newsletter link...
http://www.mcpressonline.com/mc/.6b33a18a

Rob Berendt
--
Group Dekko Services, LLC
Dept 01.073
PO Box 2000
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com

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