Technology Choices: XML-RPC vs SOAP

Ivan R. Judson judson at mcs.anl.gov
Fri Sep 13 08:24:06 CDT 2002


Terry was right this list can be used for all sorts of good things. I
think one discussion that might help drive our designs faster is on
basic technology.

Way back when we discussed what tools to build 2.0 with, we decided on a
list like:

Python 2.x (I think it was 2.0 then, it's probably true that we've moved
to 2.2)
wxWindows
Globus Toolkit 2.0
XML-RPC

I was a big advocate for XML-RPC when we had this discussion but I've
changed my mind about what the web services technology we should use is.
Remember at the time there were no standards for any of the SOAP, WSDL,
etc tools. Now WSDL and SOAP have been picked up by W3C to create
standards for them. They might fail, but since they have taken up the
effort it's worth thinking about.

I've laid out a set of trade-offs for XML-RPC vs SOAP:

XML-RPC						SOAP
-------						----
Community based "standard"			W3C standard
Simple to use					Not as simple
Limited Data Model				Arbitrarily Complex Data
Model
Tools available					Tools Available
Supported in Python				Supported in Python
Not supported by MS				Supported by all MS
products and tools
Not the target for Globus/OGSA		The target for Globus/OGSA

I'm sure there are other factors to consider, but they are both
available on all our platforms, in all our tools. Further, SOAP actually
allows us (because of the last two oints) to target convergence with MS
and Globus in development efforts if we choose to, XML-RPC doesn't.

The conclusion being, we should probably be targeting SOAP as our first
web services interface, for interop, tools availability, and to remain
true to our claim that "we adhere to standards" (not like the big bad
you know who).  I know this is a shift, but I know way back when, I was
also advocating building our system independent of the network interface
so we could easily adapt network interfaces (I know there's some of this
in Bob's venues stuff now), which was based on the pain of ripping corba
out of voyager. If we've done that, it shouldn't be too painful to
gracefully transition to SOAP from XML-RPC, as our primary target.

Thoughts?

--Ivan

..........
Ivan R. Judson .~. http://www.mcs.anl.gov/~judson
Futures Laboratory .~.  630 252 0920
Argonne National Laboratory .~. 630 252 6424 Fax
 




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