[Rets-dev] 2.0 overhead redux

[Matt Lavallee]

Thanks, Eron, good points all.

 

I think the bandwidth overhead grants some consideration to the judicious use of
attributes… just for example, for all numeric values.  The biggest content
limitation with attributes is the “no angle bracket (<)” rule… which precludes
CDATA, although permits encoded text of arbitrary length.

 

As far as extensibility goes… in my opinion, there’s very little one might
extend in the common subset of fields and, further, any change to the basic
schema at the server level will break a compliant client regardless.  In other
words, we’d have to revise the DTD anyway if we were to add a nested element to
an existing leaf node… so why not be skinny until that day comes?

 

Elements with multiple child elements are all well and good, but I only see them
used as collections in our DTD, and even then only at very high levels not at
the actual object definitions that matter.

 

-Matt

 

 

From: Eron Wright [mailto:ewright at point2.com] 
Sent: Wednesday, April 25, 2007 3:25 PM
To: Matt Lavallee; rets-dev at rets.org
Subject: RE: [Rets-dev] 2.0 overhead redux

 

I was not involved in the original discussions, but a few things that come to
mind are:

1.	Attributes have different whitespacing and encoding rules.  For large
bodies of text, elements are more efficient and do a better job at preserving
whitespace.  For small values and codes, attributes make good sense.

2.	There might be concerns in terms of schema extensibility.

3.	Elements can be multi-valued.

The benefits of XML are so widely acknowledged that I suspect it's "worth it"
despite the apparent inefficiency.  One interesting thing to note is that the
"web services" frameworks are moving to become agnostic to XML vs JSON, etc.
The .NET Framework's Windows Communication Foundation, for example, allows you
to define a web service that can be exposed simultaneously over SOAP, JSON,
ATOM, RSS, and binary formats.   A good example can be found here (start reading
at "JSON / AJAX Support"):
http://blogs.msdn.com/mwinkle/archive/2007/02/28/wcf-and-wf-in-quot-orcas-quot.a
spx

Hope this helps,

Eron Wright

Chief Architect

Point2

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