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Re: What are web services ?

  • To: Chiusano Joseph <chiusano_joseph@b...>
  • Subject: Re: What are web services ?
  • From: Razvan MIHAIU <mihaiu@m...>
  • Date: Tue, 31 May 2005 10:26:48 +0300
  • Cc: Paul Downey <paul.downey@w...>, Rex Brooks <rexb@s...>, xml-dev@l..., Michael Kay <mike@s...>
  • In-reply-to: <74B14CBC0FEB9D4EB16969F09FA51F4555AD25@M...>
  • References: <74B14CBC0FEB9D4EB16969F09FA51F4555AD25@M...>
  • User-agent: Mozilla Thunderbird 1.0 (Windows/20041206)

scjp preparation
Chiusano Joseph wrote:
Although no single, authoritative definition exists for basic terms like "service" and "Web Service", here are some fundamental characteristics that some folks believe that anything described as a "Web Service" should possess:

(1) Can interact with it through the WWW;
  
    Yes, this seems to be one of the goals. I saw in many article praising web services that they can pass thru standard proxies+firewalls because they are based on HTTP (like SOAP is)
(2) Platform- and programming language-agnostic;
(3) Interface & invocation requirements are well-described;
  
    I can some up with some well-described (in my opinion) protocol but that doesn't mean that it is going to be a web service. Microsoft can some up tomorrow with some new protocol called "M-SUPER-C" that will meet the above constrains but that does not mean that this is a web service.
    So point 3 is only valid toghether with point 9.

(4) XML-encoded interaction mechanism;
  
    This is true according to W3C, but is this valid in the general sense ? Who says that a web service must be text-based and not binary ?

(5) Payload most often is XML;
  
    "Most often" cannot be part of a definition.

(6) Loose coupling between invoker and Web Service;
  
    You mean it must not have a state (like HTTP) ?
(7) Performs a specific, well-defined function;
  
    !!!? I am really tired of such high level super-generic definitions. What entity in the computing world isn't supposed to be specific and well-defined ?

(8) May invoke other Web Services;
  
    Remote invocation is not big deal. How about a self-describing feature (WSDL) ? Can a "service" be called a "web service" if it doesn't have this feature ? How about automatic discovery (UDDI) ? Is such a feature an integral part of a web service or is it just optional ?
    Of course WSDL and UDDI are just implementations. You can replace those with ASDF and YRRT or whatever.

(9) Standards-based;
(10) Has the ability to perform its functionality synchronously or asynchronously, as needed; (i.e. does not use synchronous interaction when asynchronous is best, and vice-versa);
  
    Can you please explain what you mean by this ?


-- 
Regards,
Razvan

SCJP preparation material:

http://www.mihaiu.name/2004/sun_java_scjp_310_035/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test1/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test2/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test3/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test4/index.html





Joe

Joseph Chiusano
Booz Allen Hamilton
Visit us online@ http://www.boozallen.com

  
-----Original Message-----
From: Paul Downey [mailto:paul.downey@w...] 
Sent: Tuesday, May 31, 2005 2:26 AM
To: Rex Brooks
Cc: xml-dev@l...; Michael Kay; 'Razvan MIHAIU'
Subject: Re:  What are web services ?

Rex,

I actually think Michael's answer was bang on target. You 
only have to look at the archives of the W3C Web Services 
Architecture Working Group to see the difficulties involved 
when trying to gain consensus on the definition for basic 
terms like "Service".

    
since it is almost guaranteed that the future of computing will be 
dominated by the paradigms being developed in this field.
      
How far into the future are we talking, here?
The whole of computing, guaranteed, really?

Web services do have some significant vendor backing, but 
still have some real political and technical issues and so 
much to prove. The potential to reach the 'Web'
vision for services remains, but is likely to be somewhat 
different to the tower of Babel currently being battled for.

As someone wise said recently (i wish i could remember who):
the future is often out there in the long grass, where no-one 
is watching.

Paul



    
While this is true for the perpetual world of con artists and 
grifters, and those on whom they prey, and for the equally 
      
perpetual 
    
professional gadflies whose avocation appears to be to puncture the 
also perpetual puffed up human egotists who appear to be born 
"experts" on just about everything and whose love of their 
      
own voices 
    
vocally or verbally seems to know no bounds.

However, there is a growing body of standards and practices 
      
for both 
    
loosely coupled but well-bound WSDL and SOAP based web services AND 
RESTful web services based largely on structural 
      
capabilities inherent 
    
in the current and future Web Services Architecture 
      
promulgated by the 
    
W3C.

Please be aware when you toss out the makings for new 
      
assaults in this 
    
permathread that asking for or providing short answers for how to 
build, publish service descriptions, establish reliable connections 
for web service consumers and transact reliable, secure web service 
operations to deliver valuable, cost-worthy functionalities 
      
over the 
    
web is not wise and most likely to produce poor definitions 
      
and wider 
    
misinformation than we already have.

Since I have been working for three and half years in the 
      
OASIS WSRP 
    
TC and for the last few months in the newly formed SOA 
      
Reference Model 
    
TC, I can vouch for how difficult it is to develop sound, reliable 
specifications, definitions and practices for this arena, 
      
especially 
    
since it is almost guaranteed that the future of computing will be 
dominated by the paradigms being developed in this field.

Like it or lump it, you will be dealing with it, so spit 
      
into the wind 
    
at your own risk. However, it is always tremendous fun to 
      
watch while 
    
pedants and gurus expound on these topics.

My own position is to attempt to help shape this new 
      
technology into 
    
more workable pathways and learn it from the inside out while it is 
possible to do so. Three years ago it was almost pure hype 
      
with a tiny 
    
proportion of real work and a few major vendors vying to "own" this 
space. Now it is due to become, in the  world of  public 
      
perception, 
    
the province of equally perpetual gurus who have an almost 
irresistible compulsion to evangelize in these early stages of 
development and who tend to become "bleeding deacons" decrying the 
loss of true vision and purpose as what they consider their 
brainchildren develop their own lifecycles apart from the 
predilections of early adopters and true believers alike.

This opinion is based on observing similar processes over 
      
the course 
    
of the last 30 years of tech development..

Ciao,
Rex

At 10:29 AM +0100 5/30/05, Michael Kay wrote:
      
OK, here's my answer. The term "web service" means anything the 
speaker wants it to mean. Like "service oriented architecture" or 
"native XML database" or "electronic business" it's a 
        
fuzzy term that 
    
different people will define in different ways, depending on what 
they are trying to sell you.Michael Kayhttp://www.saxonica.com/
        
From: Razvan MIHAIU [mailto:mihaiu@m...]
Sent: 29 May 2005 17:43
To: xml-dev@l...
Subject: Re:  What are web services ?

     This is not that much off-topic. Please make the courage to 
answer :-(
          
Hi,


             Were can I find a good definition of this ? 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) ? Can 
    
we have web services without WSDL and UDDI ?


 Regards,
 Razvan
--
 Regards,
 Razvan

 SCJP preparation material:

http://www..mihaiu.name/2004/sun_java_scjp_310_035/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test1/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test2/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test3/
index.htmlwww.mihaiu.name/2004/sun_java_scjp_310_035_test4/
index.html
  
            
--
 Regards,
 Razvan

 SCJP preparation material:

http://www..mihaiu.name/2004/sun_java_scjp_310_035/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test1/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test2/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test3/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test4/index.html
          
--


Rex Brooks
 President, CEO
 Starbourne Communications Design
 GeoAddress: 1361-A Addison
 Berkeley, CA 94702
 Tel: 510-849-2309

      
--
http://blog.whatfettle.com


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-- 
Regards,
Razvan

SCJP preparation material:

http://www.mihaiu.name/2004/sun_java_scjp_310_035/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test1/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test2/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test3/index.html
http://www.mihaiu.name/2004/sun_java_scjp_310_035_test4/index.html



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