My first Web Service

[Liza (archive)]

Hello,

can you guys help me out here....?

this is part of my masters degree and hence is very important to me..... my supervisor doesn't seem to be too interested in helping me and infact is on holiday as we speak.

ok here's my question.....

can a web page be a client of a web service? if so....what language would the web page be written in? can it be a normal html page, or does it have to be written in xml or maybe even a server scripting language?

assuming that a web page can interact with a web service......how would the page locate the interface of the service(assuming this had been direct publication of the interface) ? and how would it go through the interface and make sense of it in order to bind the web service so that it can then use it?

thanks for all help rendered.

Liza

 

[Dan (archive)]

the question "how do i create a web service?" is a broad question.

to answer your first question - yes...a web page can access a web serivice. The web service would be harbored in a web server for communication (you can also use ftp and smtp).

you can create the web service using any language that can talk soap - ranging from C++ to perl. Once deployed to the web server - you have some mean of connecting to the web service (i.e. URL) For an example...using JSP - you would use the SOAP API to send the request to the service. I suggest for you to grab a book - many langs support SOAP...it's up to you how complex you want to make it.

 

[Andy Dingley]

On 6 Aug 2003 10:49:08 -0700, (Liza) wrote:

can a web page be a client of a web service?

To be a client of a web service, you need a programming language, and some component / library / language feature that lets you use a suitable protocol to talk to the web service. Candidates would be SOAP, XML-RPC, or a lower level one like HTTP (you code the SOAP engine yourself) or even SMTP.

There are many candidates for such languages.

Now what's a web page ? Does it execute on the server, or on the client ?

On the server, the web server might also use another machine that offered a web service, perhaps to collect a stock ticker or quotation service that was then incorporated in a web page. You might code this in ASP, PHP, JSP or whatever your favourite is.

On the client, you can run client-side Javascript. This can't (by itself) talk to a web service, but some dialects can achieve it by various extensions. For M$oft's JScript, it can use ActiveX objects and the MSXML.XMLHTTP object to connect to one.

It's not possible to connect to a SOAP service by simple HTTP alone, as you need to set a HTTP header line (this is a dumb feature in SOAP). I know this limits some of the Perl libraries you might otherwise choose - you need the ability to add headers to the GET.

The first SOAP client I ever saw was a demo written by Aaron Skonnard for an article in MSDN magazine. It was a client-side HTML page with JScript and MSXML. Sadly it was for an old SOAP version, and I'm not sure if it's still around (although it was an easy tweak to make it work with new SOAP servers).

assuming that a web page can interact with a web service......how would the page locate the interface of the service(assuming this had been direct publication of the interface) ? and how would it go through the interface and make sense of it in order to bind the web service so that it can then use it?

WSDL gives you the low-level stuff of how to do the binding (typing etc.) Many client-authoring tools are now using this, so as to build wizard code for you.

UDDI offers a directory service, when you want to find out who is offering a quote service for the Tony Bliar futures market.

In the middle, the "how" layer, is a bit of a minefield at the moment. It's called "choreography", and all the big players are having a bunfight over who gets to write the W3C TR. Real handbags-at-dawn stuff.

It's probable that OWL (Web Ontology Language) will start to be significant here too. Manyana.

Take a look at WebSphere in particular (and WebLogic, or even BlueStone if you can find them). Their web site has some useful white-paper stuff.