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NG an evolution of or a departure from HTTP?

From: Scott Lawrence <lawrence@agranat.com>
Date: Tue, 28 Jul 1998 21:21:08 +0000
Message-ID: <35BE40C4.DE666F6@agranat.com>
To: NG Comments <www-http-ng-comments@w3.org>
To quote from the 'Short and Long Term Goals' [1] of the W3C HTTP-NG
  Activity [2]:

     The goal of the HTTP-NG project is to test the hypothesis that
     the current HTTP/1.X approach to web protocol design can be
     replaced with one in which the Web is expressed as a particular
     set of interfaces on top of a generic distributed object system
     designed with Internet constraints in mind. We expect that a
     layered approach would bring many benefits to the Web,
     including easier evolution of the protocol standard, interface
     technology that would facilitate Web automation, easier
     application building, and so on.

  First, I think that the more interesting question is whether or not
  the current approach to web protocols _should_ (as opposed to 'can'
  above) be "replaced with one in which the Web is ... a generic
  distributed object system".

  It _may_ be true that a generic distributed object system would
  provide a better foundation for some kinds of distributed
  applications.  However, I think that it is usefull to examine
  whether or not this is true for the Web as a whole and for future
  versions of HTTP in particular.

  I believe that the explosive growth of the Web can in large part be
  traced to the loose coupling between servers and clients.  The
  structure (I hesitate to call it an 'architecture') of the Web to
  this point has specifically _not_ been that of a distributed
  application, but a set of applications communicating in a simple
  way, passing content that each is free to interpret (or
  misinterpret) according to its own capabilities.  Servers in general
  have only a vague notion of the capabilities of clients, and clients
  only a very simple set of interactions with servers.  While a
  problem if viewed as building a distributed application, this has
  contributed to making it easy to experiment with new capabilities.
  This easy experimentation, even on a large scale, has caused
  capabilities to undergo a 'selection of the most popular'.  Server
  operators are often faced with the decision of whether or not to use
  a particular technology that may not be deployed widely enough to
  meet thier needs, and have generally found good ways to deal with
  the tradeoffs (links to pluggins or alternate versions of a page),
  but as a particular technology becomes available that provides
  attractive new capabilities, users tend to adopt them quickly and
  servers can use them with increasing confidence (eg. inline images,
  animated GIFs, RealAudio, frames, Javascript).

  With the exception of the MUX layer, the rest of the architecture
  examined by the HTTP-NG project represents more a radical departure
  from HTTP than an evolution of it.  It abandons not only loose
  server/client coupling, but also the fact that HTTP is human
  readable - a factor that has contributed to making HTTP interactions
  easy to debug, and which follows in the footsteps of the most widely
  deployed protocols above TCP in the Internet protocol family (SMTP,
  NNTP).

  Distributed object oriented frameworks may be a good way to build
  some kinds of distributed systems, but I don't believe that anyone
  can cite an example of any distributed system that has seen anything
  like the rapid evolution and acceptance of the loosely coupled
  components that make up the Web; let us not abandon them lightly.

  If the existing distributed object frameworks have shortcomings as
  enhancements to existing Web technologies, those should be addressed
  either by evolving them or by replacing them (perhaps with something
  like the framework HTTP-NG examined).  I don't think, however that
  this should be viewed as a replacement for the loosely coupled
  approach of HTTP; it should instead be considered as a new protocol
  complementry to HTTP and unencumbered by the necessity of any sort
  of backward compatibility with it.  The whole discussion of how one
  might implement HTTP/1.x using HTTP-NG becomes moot, and whatever it
  is called (OTIP - Object Transport Interaction Protocol) is free to
  be designed to meet the needs of a different class of problems for
  which HTTP is ill suited.  HTTP/X need not be the only protocol in
  the Web (it isn't even now); let us not try to build a single hammer
  than can drive everything from carpet tacks to bridge pilings.


-- 
Scott Lawrence            Consulting Engineer        <lawrence@agranat.com>
Agranat Systems, Inc.   Embedded Web Technology     http://www.agranat.com/
Received on Tuesday, 28 July 1998 17:20:40 EDT

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