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On Tue, 31 May 2005, Razvan MIHAIU wrote:
> Paul Downey wrote:
> > On 29 May 2005, at 17:42, Razvan MIHAIU wrote:
> >>> Were can I find a good definition of this ?
> > my definition is it's a service made available using Web based
> > technologies targeted at computer, as opposed to human, agents.
> It seems that you are right (according to W3C):
> "The World Wide Web is more and more used for application to application
> communication. The programmatic interfaces made available are referred
> to as Web services."
> ... "applications to application". What this definition implies is that
> the term is very generic. Everything can be a web service:
> 1. a cgi
> 2. an ejb
> 3. a php/perl script
> the only restriction is that the above entity must communicate with a
> computer and not a human.
> However there must be other restrictions for web services. After
> reading the other definitions I came up with the following list:
> 1. interoperable between OSes (a message written on one OS should be
> easily readable on another); this seems to imply the use of XML; what
> other technology can achieve this ?
Look at ASN.1. It has been around since 1984 for interoperablity
regardless of OS, machine architecture or programming language. And by
the way, it also now has XML as one of its encoding rules.
> 2. it must be an open standard (issued by Oasis or W3C); this
> restriction should rule out any "cgi, ejb, perl/php script" as a web
> service; you could have a cgi acting as a web service but only if it
> works according to a certain open protocol (this leads us to the next
ASN.1 is an ISO/IEC International Standard and an ITU-T Recommendation.
You can download the specifications free from the ITU-T website.
> 3. it must have an open interface (e.g. it must work according to a
> certain protocol); as I read in another reply there are at least 3
> protocols to match this criteria: SOAP, REST, XML-RPC
You might want to take a look at ITU-T Rec. X.892 (Fast Web Services).
> Any other restrictions ?
> > Some attempts at definitions:
> > http://www.w3.org/2002/ws/
> > http://en.wikipedia.org/wiki/Web_services
> > http://ws-i.org/about/Default.aspx
> > http://msdn.microsoft.com/webservices/
> > Google until your blue in the face ..
> >>> A web service must be based on SOAP in order to belong in this
> >>> category ? A web service must use XML for transferring data (like
> >>> SOAP) ?
> > Web services are synonymous with SOAP, WSDL and UDDI in many
> > peoples' eyes, though they've taken so long to arrive
> > that the marketeers are busy re-branding it 'SOA', I
> > guess SOAP is now Service Oriented Architecture Protocol :-)
> >>> Can we have web services without WSDL and UDDI ?
> > Sure, why ever not? It's the service that's important, not
> > how you elect to describe, catalogue or sell them.
> Doesn't a web service imply the fact that it can be found in a
> standard way ? Or this is just an add-on to the web service definition
> that may or may not be fulfilled.
> The truth is I have yet to see a programmer that answers this
> question with a big smile. Why is the question difficult ? Perhaps
> because behind web services there are so many technologies or perhaps
> because the term has not finished evolving yet.
> SCJP preparation material:
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