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Seetharama Rao Durbha wrote:
>
> I thought so - but then was not quite sure if a solution akin to the web
> load balancing/fail-over is a better one, or giving individual control to
> the customers is a better one.
Not sure what you're driving at here - load-balancing should be provided
if required, wherever it is required - that is, whether one is a service
provider or service consumer - or both - should not make a difference.
It's all about whether or not it is required given the load.
> The advantage with current way (of providing
> load-balancing / fail-over at the network service provider or perimeter) is
> that it is already in place, at least for those people with high content and
> visits. However, I am sure that Orgs with high-content web requests are not
> the ones who need to provide highly reliable web services (at least not
> 1-1), so others would need different solutions.
Web Services reliability is actually a different, but somtimes related,
topic that involves quality of service (QoS) requirements such as
guaranteed delivery and guaranteed message ordering (see the work that
we have been doing in OASIS WS-Reliability). An example of these being
related is where a receiving system does not have adequate load
balancing capabilities, and a response to a sent message (using
reliability features) is not received by the sender within a predefined
window - which will cause either a resend or a termination of attempts
to resend that message, depending on the number of attempts vs. some
predefined parameter on the sender side.
> And, probably, making the
> choices part of the WSDL,
If you mean the choice of using load balancing or not, then this could
be incorporated into a WSDL document in the manner described below
(multiple soap:address values). Of course, simply having multiple
addresses does not mean that load balancing is done - it just sets up
the foundation for it.
> or a dynamic retrieval of those choices from a
> UDDI repository (basically a standards-based way) would be a good idea.
Yes, one can use UDDI to dynamically retrieve a WSDL document of course.
So if this means retreiving a WSDL document that contains multiple
soap:address values, then that is on target.
> I will take a look at WSRP.
I don't believe that WSRP incorporates the notion of load balancing into
their spec (at least the last I read), because it's more of an
implementation issue. Rex will correct me if I am wrong.
Kind Regards,
Joe Chiusano
Booz Allen Hamilton
Strategy and Technology Consultants to the World
> Thanks,
> Seetharama
>
> -----Original Message-----
> From: Rex Brooks [mailto:rexb@starbourne.com]
> Sent: Monday, August 30, 2004 7:17 AM
> To: Chiusano Joseph; Seetharama Rao Durbha
> Cc: xml-dev@lists.xml.org
> Subject: Re: [xml-dev] Fault-tolerance in web services
>
> Indeed, not naive at all. Load balancing and
> scalability issues are here already in WSRP, and
> will need to be taken into account by IT
> architects as they begin to fashion portal-based
> IT solutions end to end of an enterprise.
> Although heterogeneous environments can be
> accommodated, the tier of largest companies will
> almost certainly need to rethink IT strategies in
> terms of investing in the most efficient and
> scalable systems. That is going to be more
> efficient with systems designed to scale from day
> one AND work with more heterogeneous partners.
> Not easy. Not simple.
>
> Ciao,
> Rex
>
> At 3:51 PM -0400 8/30/04, Chiusano Joseph wrote:
> >That doesn't seem at all like a naïve question, especially since your
> >additional information is right on the mark. The situation you imagine
> >is - I am certain - often done in practice, by offering a service at
> >multiple addresses.
> >
> >Kind Regards,
> >Joe Chiusano
> >Booz Allen Hamilton
> >Strategy and Technology Consultants to the World
> >
> >Seetharama Rao Durbha wrote:
> >>
> >> Just a naïve question - fault tolerance in web services - for example,
> >> providing multiple service/soap:address - should that be part of a
> WSDL/SOAP
> >> client functionality, or should that be a native support provided by the
> >> provider?
> >>
> >> I can imagine situation where services are multi-hosted and a particular
> >> provider would like to be able to explicitly identify those locations to
> the
> >> clients, in case one fails, or even for load-balancing, if that is a
> >> concern.
> >>
> >> Thanks,
> >> Seetharama Rao Durbha
> >> Cell : 510-673-1843
> >> Office : 510-742-4228
> >>
> >> -----------------------------------------------------------------
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> >>
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> >
> >--
> >Kind Regards,
> >Joseph Chiusano
> >Associate
> >Booz Allen Hamilton
> >
> >-----------------------------------------------------------------
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> >initiative of OASIS <http://www.oasis-open.org>
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>
> --
> Rex Brooks
> GeoAddress: 1361-A Addison, Berkeley, CA, 94702 USA, Earth
> W3Address: http://www.starbourne.com
> Email: rexb@starbourne.com
> Tel: 510-849-2309
> Fax: By Request
>
> -----------------------------------------------------------------
> The xml-dev list is sponsored by XML.org <http://www.xml.org>, an
> initiative of OASIS <http://www.oasis-open.org>
>
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--
Kind Regards,
Joseph Chiusano
Associate
Booz Allen Hamilton
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