[XML-SIG] XML serialization / marshalling via DTD

[george willis]

Nothing is "wrong" with SOAP, or its predessesor XML-RPC -- they are just
not object serialization mechanisms, but rather RPC mechanisms that use XML
to transport data.

To get reusable code, we must think abstract.  XML is nothing more and
nothing less than a universal standard for the representation of serialized
object models for transport between systems.  What is needed is a generic
serializer/deserializer like that found in java.

If you have ever "marshalled" objects the Microsoft way, you know what a
royal pain it is to write your own marshalling code.  If you have ever
"serialized" objects the java way, you wonder why this wasn't automated
sooner.

A mechanism which automates the serialization of objects via introspection
of the object model, and that automates deserialization of objects via
parsing the stream and creating the necessary classes/types (if not present)
and then instantiating objects that that conform to the stream, has many
uses -- persistance, rpc, distributed objects, etc.

The key to good architectures lies in the building blocks.  We have SOAP for
rpc - and it will utilize some sort of XML-Schema to refine parameters in
the rpc call.  But how does the XML-Schema get turned into objects that the
receiving system can then use to perform its function utilizing OOP?  How
does the resulting output remain independant and loosely coupled from the
plathora of standards like HTML, WML, XML, XML-Schema, XML-RD, etc., if not
through a mechanism that takes the object model that results after the rpc
call, and then serializing this to the appropriate dialect?

The process of ser/deser exists embedded and constrained in several places
such as XMLDocument,XMLWidgets, XMLObjects, etc.
WHAT WE NEED IS THIS MECHANISM, JUST AS IT IS IN JAVA XML SERIALIZATION
CODE, TO PROVIDE AUTOMATED SER/DESER USING THE EXISTING FOUNDATIONAL WORK OF
SAX, DOM, AND PLUGGABLE PARSERS, SO THAT WE MAY LEVERAGE ALL THE BENEFITS OF
OO REUSE THROUGH THE CONSUMING TECHNOLOGIES OF RPC, PERSISTANCE, ETC.

I hope this clarifies my previous post.  I thank you for taking the time to
respond and welcome any additional insights you may have.


------Original Message------
From: "Fredrik Lundh" <effbot@telia.com>
To: "george willis" <gwillis@mail.com>, <xml-sig@python.org>
Sent: May 31, 2000 4:41:30 PM GMT
Subject: Re: [XML-SIG] XML serialization /  marshalling via DTD

what's wrong with XML-RPC and/or SOAP?

george willis <gwillis@mail.com> wrote:
Goal: To provide object serialization/deserialization mechanism for python
(similar to what is provided in java) using XML, a DTD, and a generic XML
API and parser. Ultimate use will be inside the Zope environment. See
http://iceberg.sourceforge.net/ for similar concept using java.

Background: I have found several leads, pieces of code, etc. In fact, it
seems too many people have taken a stab at this without realizing the
generic functionality that would solve so many problems. There are
importers without exporters, importers to screen widgets, importers that do
there own parsing, etc.

Question: Has anyone embraced this problem to develop an architecturally
sound solution to object serialization via XML using XML-RD, XML-Schemas, or
other refinements of the DTD specification?

George Willis
gwillis@mail.com
voice: (706)206-0091
  fax: (240)337-8593 
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