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the MASP XML protocol

From: Mark Jones <jones@research.att.com>
Date: Tue, 2 May 2000 15:48:08 -0400 (EDT)
Message-Id: <200005021948.PAA15752@glad.research.att.com>
To: xml-dist-app@w3.org
Cc: tony@att.com, jones@research.att.com
Gang,

I've been a lurker in this group for a while now, but haven't had much
time to be an active participant.

I thought I should point out an XML-based protocol that I will be
presenting in the poster session at WWW9 in a couple of weeks.  We
created it about two years ago when we needed a client-server protocol
for a new Mediated Attribute Store service that I was developing as a
research prototype for some enterprise messaging applications at AT&T.
Although the Mediated Attribute Store Protocol (MASP) was developed
for this application, the ideas are suitably general to cover most
synchronous client-server applications (and probably adaptable to
asynchronous ones as well).

For simplicity, we decided to use an *entirely* XML-based structure
for the protocol.  It is not built on HTTP (firewall issues were not
paramount for our initial setting).  Literally, the client and server
sides simply open up socket connections and exchange ongoing XML
"documents".  The client-to-server connection passes the requests for
service; the server-to-client document passes the corresponding
responses.  There is error handling, a limited form of attribute
serialization, a generalized encoding metatag (EDATA), etc.  There
were some terrific side-benefits to an XML protocol in an exploratory
research project, including extensibility (easy to add new commands),
protocol tracing (readable trussing!) and server debugging (server
diagnostics as XML comments are extensible and don't break client
libraries!).

The fact that it is entirely in XML means that a client platform just
needs to have an XML parser available.  This might be good for fairly
thin clients, for example.  We have adapted James Clark's parser for a
C/C++ client API library.  Other users have used other off-the-shelf
XML parsers for MASP client libraries and applications in Java and
Perl.  One project is completing a JavaMail provider implementation
that uses MASP.  I tend to view simple XML cross-platform protocols as
a kind of "poor man's CORBA" -- with a lot less hair for relatively
straightforward applications.

A more complete paper than that found in the WWW9 poster session
can be found at http://www.research.att.com/~jones/www9paper.htm.
I will be doing demos in the poster session on Wednesday evening,
May 17, if you'd like to drop by for a look.  The paper and demo
focus on the XML protocol issues and not the MASP service concept
per se; details on MASP will be forthcoming later.

Cheers,

Mark A. Jones

AT&T Labs - Research
Shannon Laboratory
Room A201
180 Park Ave.
Florham Park, NJ  07932-0971

email: jones@research.att.com
phone: (973) 360-8326
  fax: (973) 360-8970
Received on Tuesday, 2 May 2000 15:48:18 GMT

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