Using reflection to call an ASP.NET web service

Question

Say I have an ASMX web service, MyService. The service has a method, MyMethod. I could execute MyMethod on the server side as follows:

MyService service = new MyService();
service.MyMethod();

I need to do similar, with service and method not known until runtime.

I'm assuming that reflection is the way to go about that. Unfortunately, I'm having a hard time making it work. When I execute this code:

Type.GetType("MyService", true);

It throws this error:

Could not load type 'MyService' from assembly 'App_Web__ktsp_r0, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'.

Any guidance would be appreciated.

Answer 1

I'm not sure if this would be the best way to go about it. The most obvious way to me, would be to make an HTTP Request, and call the webservice using an actual HTTP GET or POST. Using your method, I'm not entirely sure how you'd set up the data you are sending to the web service. I've added some sample code in VB.Net

Dim HTTPRequest As HttpWebRequest
Dim HTTPResponse As HttpWebResponse
Dim ResponseReader As StreamReader
Dim URL AS String
Dim ResponseText As String

URL = "http://www.example.com/MyWebSerivce/MyMethod?arg1=A&arg2=B"

HTTPRequest = HttpWebRequest.Create(URL)
HTTPRequest.Method = "GET"

HTTPResponse = HTTPRequest.GetResponse()

ResponseReader = New StreamReader(HTTPResponse.GetResponseStream())
ResponseText = ResponseReader.ReadToEnd()

Answer 2

I looked back at this question and I think what you're facing is that the ASMX code will be built into a DLL with a random name as part of the dynamic compilation of your site. Your code to look up the type will, by default, only search its own assembly (another App_Code DLL, by the looks of the error you received) and core libraries. You could provide a specific assembly reference "TypeName, AssemblyName" to GetType() but that's not possible in the case of the automatically generated assemblies, which have new names after each recompile.

Solution.... I haven't done this myself before but I believe that you should be able to use something like this:

System.Web.Compilation.BuildManager.GetType("MyService", true)

as the BuildManager is aware of the DLLs it has created and knows where to look.

I guess this really doesn't have to do with Web Services but if it were your own code, Daren's right about Facade patterns.