Re: Web Service Description and stateful services

+1

Christopher Ferris
STSM, Emerging e-business Industry Architecture
email: chrisfer@us.ibm.com
phone: +1 508 234 3624

www-ws-arch-request@w3.org wrote on 06/24/2003 04:07:03 AM:

> 
> * Cutler, Roger (RogerCutler) <RogerCutler@chevrontexaco.com> 
[2003-06-23 10:43-0500]
> > Well put, Eric.  It seems to me that you could dress this up just a 
bit
> > and come up with some candidate verbiage for the document ...  Hint,
> > hint ...
> [..]
> 
> Since we are talking about verbiage for the document...
> 
> > -----Original Message-----
> > From: Newcomer, Eric [mailto:Eric.Newcomer@iona.com] 
> > Sent: Sunday, June 22, 2003 12:21 PM
> > To: Assaf Arkin
> > Cc: Ugo Corda; www-ws-arch@w3.org
> > Subject: RE: Web Service Description and stateful services - (on the
> > 'www-ws@w3.org' list) Debating on a) Stateful Web Service Instances b)
> > Stateful Interaction - OGSI
> > 
> > 
> > 
> > As Roger pointed out, we are often talking on this list about the same
> > things using different terms, and about different things using the 
same
> > terms.  The normal case, I guess, without an agreed architecture...
> > 
> > Anyway, I wanted to clarify a point in the discussion.  There are at
> > least two kinds of state mentioned in this thread - application state
> > and transport state. 
> > 
> > It's very true that a majority of Web sites manage some application
> > state.  But HTTP does not include stateful sessions - meaning HTTP 
does
> > not define a way to maintain a connection beyond what's necessary to
> > execute a single HTTP method.  Many other communication protocols do
> > support the notion of connections that live beyond a single method
> > invocation (including those used in TP monitors whose applications are
> > stateless), but of course that type of connection state requires
> > resources impractical if not impossible to allocate over the WAN which
> > is the Web.
> 
> This is not completely true. HTTP/1.1 does allow you to keep a TCP
> connection to a server open that you could use to maintain some state:
> 
>    http://www.w3.org/Protocols/rfc2616/rfc2616-sec8.html
> 
> A few comments though:
> - using a proxy would probably make this method fail: the persistent
>   connection is hop-to-hop, and the proxy may use its connection to a
>   server for 2 of its clients.
> - in practice, HTTP connections are not maintained for a long time in
>   most servers (something like 30 seconds for Apache whereas Jigsaw
>   doesn't close the connection until it's forced to) and firewalls
>   often terminate stale TCP after some time.
> - using this persistent connection to maintain state is not RESTful
>   since the subsequent HTTP requests would not have all the
>   information necessary (statelessness).
> 
> So I would probably just drop "meaning HTTP does [..] execute a single
> HTTP method."
> 
> Regards,
> 
> Hugo
> 
> -- 
> Hugo Haas - W3C
> mailto:hugo@w3.org - http://www.w3.org/People/Hugo/
>

Received on Thursday, 26 June 2003 03:25:44 UTC