I
don't believe having many clients is the real reason. All enterprise-level
systems handle multiple clients and most of them deal with instance specific
(session) state information. What makes a web service different is that it
is platform independent and expected to be 100% interoperable. Now,
interoperability is ensured by specifying your service using standard wsdl
and there is no standard way to define state information in wsdl. In other
words, you cannot build a web service which is stateful and at the same time
interoperable.
Also,
many service implementations do not support state
management.
Yet
another point is, in an architectural view web services are mostly SOA
implementations and they use stateless protocols such as http, jms etc. An
ideal web service performs one or more business functions to accomplish a
logical business 'service'. Client state does not come into the picture in any
of these and it just doesn't look natural.
Jai
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Thursday, December 23, 2004 5:50 AM
To: [EMAIL PROTECTED]
Subject: RE: Web Service with state
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Thursday, December 23, 2004 5:50 AM
To: [EMAIL PROTECTED]
Subject: RE: Web Service with state
Each web service instance could, potentially, process requests from many different clients. I'm sure that this is the reason for the stateless requirement. Static state is not an issue, only instance state, where the service stores information from previous requests to process future requests, is prohibited. State can be stored in a session, if necessary.
Tony
"Rajdeep Dua" <[EMAIL PROTECTED]> wrote on 23/12/2004 10:08:03:
> I had asked this question yesterday also.
> Wanted to know why the J2EE and JAX-RPC specs talk
> about web service to be represented using stateles
> components when there can be several instances of
> usage for a stateful usage
> --- Merten Schumann <[EMAIL PROTECTED]> wrote:
>
> > Yes, in fact in J2EE 1.4 only stateless session
> > beans (not statefull
> > ones) can expose their interface as web service.
> > But, the quotation was
> > not that implementation specific, it was "web
> > service has to be
> > state-less" and this is not true IMHO. I do maintain
> > "global state" in
> > my web service (just static variables right now)
> > which could be accessed
> > by any SLSB instance within the same JVM. Works for
> > EJB way (SLSB) and
> > JAX-RPC way.
> >
> > cu
> > Merten
> >
> >
> > ________________________________
> >
> > From: Peter Smith
> > [mailto:[EMAIL PROTECTED]
> > Sent: Thursday, December 23, 2004 5:11 AM
> > To: [EMAIL PROTECTED]
> > Subject: Re: Web Service with state
> >
> >
> >
> >
> >
> > Have read that web service has to be state-less.
> > Why is that?
> >
> >
> >
> > Where did you read that?
> > Maybe it's a hint which should be followed if
> > possible,
> > but nothing more
> > IMHO.
> >
> >
> >
> > From J2EE1.4 web services point of view this is not
> > a "hint" at
> > all....
> >
> > See "Web Services for J2EE, Version 1.0" (aka
> > JSR-109 for
> > J2EE1.4) [ref
> > http://www.jcp.org/en/jsr/detail?id=109]
> >
> > [section 5.3.2.1 EJB Container programming model] A
> > Service
> > implementation bean *must* be a stateless object
> >
> > [section 5.3.2.2 Web Container programming model] A
> > Service
> > implementation *must* be a stateless object
> >
> > and [section 1.4 document conventions] "MUST"
> > meaning is from
> > RFC 2119 [ref http://www.faqs.org/rfcs/rfc2119.html]
> > meaning "absolute
> > requirement of the specification"
> >
> > Peter.
> >
> >
> >
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>
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