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asp.net : WSDL Generated Proxy Classes?
accessed in exactly the same way as how a normal class' methods & properties are accessed. So what for does ASP.NET generate proxy classes (using WSDL) which consume more hard disk space & resources? For e.g. consider the following code which exists in a user-defined class file: Imports System Imports System.Data Imports System.Web.Services Namespace AddNumbers Public Class Calculator : Inherits WebService <WebMethod()> Public Function Add(ByVal intA As Integer, ByVal intB As Integer) As Integer Return (intA + intB) End Function End Class End Namespace The above code spans just 11 lines but if the above code (excluding the 2 Namespace lines) is encapsulated in an ASMX file after which WSDL is used to generate a corresponding class file, the class file spans almost 100 lines (excluding the commented lines). Moreover, most part of the code in the generated class is not comprehensible to newbies like me. So why use WSDL to generate a class file? Also there definitely must be some additional overheads involved in this approach, isn't it? Thanks, Arpan
Hi,
[quoted text, click to view] Arpan wrote: > Web Services make use of proxy classes whose methods & properties are > accessed in exactly the same way as how a normal class' methods & > properties are accessed. So what for does ASP.NET generate proxy > classes (using WSDL) which consume more hard disk space & resources? <code snipped> [quoted text, click to view] > The above code spans just 11 lines but if the above code (excluding the > 2 Namespace lines) is encapsulated in an ASMX file after which WSDL is > used to generate a corresponding class file, the class file spans > almost 100 lines (excluding the commented lines). Moreover, most part > of the code in the generated class is not comprehensible to newbies > like me. So why use WSDL to generate a class file? Also there > definitely must be some additional overheads involved in this approach, > isn't it? > > Thanks, > > Arpan WSDL is Web Service Description Language. It is a standard which is used to describe what the Web Service can do. The advantage of generating a WSDL file is that each client can download the WSDL file and generate proxy "on the fly". This is what Visual Studio does when you create a WebReference to a web service, and it generates proxies. However, there are also other consumers of web services (ATLAS in JavaScript), and they also create proxies in JavaScript dynamically using the WSDL file. Since JavaScript is a very different language than C# and VB.NET, and since web services may actually be written in yet other languages, WSDL abstracts the language differences and allows different languages to communicate through this medium. It's very possible to do AJAX without SOAP and without WSDL. The code is much thinner then. But SOAP and WSDL offer an additional level of comfort for the consumer of web services. ..NET creates WSDL files automatically (just use the URL myService.asmx?WSDL), but other providers of web services (Google comes in mind) also deliver WSDL files with their web services. HTH, Laurent -- Laurent Bugnion, GalaSoft Software engineering: http://www.galasoft-LB.ch Private/Malaysia: http://mypage.bluewin.ch/lbugnion
[quoted text, click to view]
>The advantage of generating a > WSDL file is that each client can download the WSDL file and generate > proxy "on the fly". But what proxy classes do, the same can be done using business objects. In other words, the logic that a proxy class encapsulates, the same logic can be implemented using a business object i.e. both of them can be used to retrieve data dynamically but using WSDL means the client has to save the proxy file (along with the disco & results.discomap files though not necessarily) in his machine thus consuming disk space but with business objects, the client needn't save anything on his hard disk. Moreover to access the methods & properties in a proxy file, the client has to pass commands to the Web Service (which maybe preceded by first finding where the Web Service exists using DISCO) but with business objects, there isn't any need for clients to use any extra tools like WSDL.exe & DISCO.exe to access the business object's methods & properties. Both Web Services & business objects require compiled objects that are implemented in ASP.NET pages. An ASP.NET book for beginners states that the ONLY difference between Web Services & business objects is that with Web Services, the compiled object (i.e. the proxy class) can reside anywhere on the Internet. In other words, the ASP.NET page can be located on a client's home computer in New York while the Web Service resides on a server which is in Tokyo. But even business objects that reside on a server in Tokyo can be accessed by an ASP.NET page which is located in a client's machine in New York! So what's the difference between Web Services & business objects or what are the advantages of using Web Services (using WSDLs & sometimes DISCOs) over business objects? Thanks, Regards, Arpan [quoted text, click to view] Laurent Bugnion wrote:
> Hi, > > Arpan wrote: > > Web Services make use of proxy classes whose methods & properties are > > accessed in exactly the same way as how a normal class' methods & > > properties are accessed. So what for does ASP.NET generate proxy > > classes (using WSDL) which consume more hard disk space & resources? > > <code snipped> > > > The above code spans just 11 lines but if the above code (excluding the > > 2 Namespace lines) is encapsulated in an ASMX file after which WSDL is > > used to generate a corresponding class file, the class file spans > > almost 100 lines (excluding the commented lines). Moreover, most part > > of the code in the generated class is not comprehensible to newbies > > like me. So why use WSDL to generate a class file? Also there > > definitely must be some additional overheads involved in this approach, > > isn't it? > > > > Thanks, > > > > Arpan > > WSDL is Web Service Description Language. It is a standard which is used > to describe what the Web Service can do. The advantage of generating a > WSDL file is that each client can download the WSDL file and generate > proxy "on the fly". This is what Visual Studio does when you create a > WebReference to a web service, and it generates proxies. However, there > are also other consumers of web services (ATLAS in JavaScript), and they > also create proxies in JavaScript dynamically using the WSDL file. Since > JavaScript is a very different language than C# and VB.NET, and since > web services may actually be written in yet other languages, WSDL > abstracts the language differences and allows different languages to > communicate through this medium. > > It's very possible to do AJAX without SOAP and without WSDL. The code is > much thinner then. But SOAP and WSDL offer an additional level of > comfort for the consumer of web services. > > .NET creates WSDL files automatically (just use the URL > myService.asmx?WSDL), but other providers of web services (Google comes > in mind) also deliver WSDL files with their web services. > > HTH, > Laurent > -- > Laurent Bugnion, GalaSoft > Software engineering: http://www.galasoft-LB.ch > Private/Malaysia: http://mypage.bluewin.ch/lbugnion > Support children in Calcutta: http://www.calcutta-espoir.ch
Hi,
[quoted text, click to view] Arpan wrote: >> The advantage of generating a >> WSDL file is that each client can download the WSDL file and generate >> proxy "on the fly". > > But what proxy classes do, the same can be done using business objects. > In other words, the logic that a proxy class encapsulates, the same > logic can be implemented using a business object i.e. both of them can > be used to retrieve data dynamically but using WSDL means the client > has to save the proxy file (along with the disco & results.discomap > files though not necessarily) in his machine thus consuming disk space > but with business objects, the client needn't save anything on his hard > disk. I think that you're missing the point that web services are not tied to a technology or an environment, and that the proxy classes can be (and often are, for example in ATLAS) generated dynamically during runtime. In that scenario, nothing is saved on the client, and a description file is needed. The .NET way of using "static" web references to consume web services is, IMHO, rather the exception. I think that everything which SOAP does can be done in other more efficient ways, for example using simpler AJAX. But SOAP offers an additional level of comfort for the user, which explains why it's "bloated" (which is the most common criticism found against SOAP based web services). HTH, Laurent [quoted text, click to view] > -- > Moreover to access the methods & properties in a proxy file, the client > has to pass commands to the Web Service (which maybe preceded by first > finding where the Web Service exists using DISCO) but with business > objects, there isn't any need for clients to use any extra tools like > WSDL.exe & DISCO.exe to access the business object's methods & > properties. > > Both Web Services & business objects require compiled objects that are > implemented in ASP.NET pages. An ASP.NET book for beginners states that > the ONLY difference between Web Services & business objects is that > with Web Services, the compiled object (i.e. the proxy class) can > reside anywhere on the Internet. In other words, the ASP.NET page can > be located on a client's home computer in New York while the Web > Service resides on a server which is in Tokyo. But even business > objects that reside on a server in Tokyo can be accessed by an ASP.NET > page which is located in a client's machine in New York! > > So what's the difference between Web Services & business objects or > what are the advantages of using Web Services (using WSDLs & sometimes > DISCOs) over business objects? > > Thanks, > > Regards, > > Arpan Laurent Bugnion, GalaSoft Software engineering: http://www.galasoft-LB.ch Private/Malaysia: http://mypage.bluewin.ch/lbugnion
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