Re: OO style Webservices or not
- From: "Jay B. Harlow [MVP - Outlook]" <Jay_Harlow_MVP@xxxxxxx>
- Date: Wed, 3 Aug 2005 11:35:14 -0500
Nicholas,
| This is a tricky subject. I think what a good number of people don't
| realize is that web services are not OO, and as a result, there is not a
lot
| of fidelity when trying to map one to the other.
I agree they are not OO per se, however I disagree about the fidelity. If
each web service binds to the same WSDL, then there should (*should*) be
high fidelity between them.
| However, you can't really define interfaces on a web service. That
| doesn't mean that you can't follow a contract (which is what interfaces
are
| all about).
Actually I understand you can define "interfaces" on web services. You use
the WebServiceBindingAttribute to indicate which "interface" this web
service/web method is binding to. By "interface" I mean which WSDL document
that defines the web service binds to/implements.
The client simply replaces which URL it refers to. Each specific web service
can "implement" the exact same WSDL.
For an introduction see:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnservice/html/service02202002.asp
Unfortunately I don't have a good example with code...
| Then, on the client side, you declare your interface. You then
generate
| web references to each of the different implementations on the server,
| creating separate web-proxies.
Based on the above. The client only needs a single web-proxy, however it
would need to change what web address it was using. Either using a Dynamic
URL or WebClientProtocol.Url.
Jay
"Nicholas Paldino [.NET/C# MVP]" <mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message news:O2vabIEmFHA.3336@xxxxxxxxxxxxxxxxxxxxxxx
| Allan,
|
| This is a tricky subject. I think what a good number of people don't
| realize is that web services are not OO, and as a result, there is not a
lot
| of fidelity when trying to map one to the other. Web services are
| inherently stateless, while OO is all about the ability to encapsulate
state
| in an object (or rather, that's a big cornerstone of it).
|
| That being said, I think that your fellow programmer is wrong. Adding
| methods with just another name on it will just make things confusing.
What
| it sounds like you want here is interfaces.
|
| However, you can't really define interfaces on a web service. That
| doesn't mean that you can't follow a contract (which is what interfaces
are
| all about). What you need to do is have each of your web services have
the
| same method declarations. Then, you place the different implementations
of
| these method declarations in different directories, so that they have
| different URLs (it also makes maintenence of the code easier).
|
| Then, on the client side, you declare your interface. You then
generate
| web references to each of the different implementations on the server,
| creating separate web-proxies.
|
| You can then extend from each of these (since you don't want to play
| with IDE-generated code) to implement the interface.
|
| Once you have that, you should have a number of classes that implement
| the interface, which you can now use a factory pattern to create
(returning
| just a reference to the interface).
|
| Hope this helps.
|
|
| --
| - Nicholas Paldino [.NET/C# MVP]
| - mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx
|
| "Allan Ebdrup" <comaeb@xxxxxxxx> wrote in message
| news:uYHYWaDmFHA.320@xxxxxxxxxxxxxxxxxxxxxxx
| >I just had a discussion with one of my fellow programmers.
| > We have a class for doing some logging and sending an email, it has 5
| > different scenarioes of loggin that are common enough to share a class
and
| > database tables.
| > In the future there might be new scenarioes that require their own
custom
| > classes and database tables.
| >
| > Now we want to expose some of our logging class's methods as webservices
| > (more a group of function calls called in one batch)
| >
| > I want to use an OO-like approach to laying out the webservice where we
| > have the methods of this one logging class in one .asmx file and create
| > other .asmx files for the future logging classes. Then we group all the
| > logging .asmx files together in the same namespace (and directory)
| >
| > He want's to bunch all the Add methods together and have a .AddClass1
| > method and a .AddClass2 method and so on in the same .asmx file
| >
| > What approach is the best? Does one not apply some OO principles to
| > webservices (I mean: they are declared as a class with webmethods) or
does
| > on simply create function libraries with some (hopefully) meaningfull
| > grouping of functions.
| >
| > I hope you have some insights to a best practice for the architecture of
| > webservices.
| >
| > Kind Regards,
| > Allan Ebdrup
| >
|
|
.
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