Call a Web Service Without Adding a Web Reference

Introduction

A client requested that for some reason he cannot add a Web Reference and wanted to specify the web service URL in web.config or hardcode it. Hence, my first article:)

Background

I did create this source more than a year ago. I used the internet to get information/ideas regarding this.

I am copying from my blog.

Using the Code

1. Create a class as with "DynamicWebService" and new method "CallWebService".
2. Create an object of this class and call method "CallWebService" with web service URL and other parameters:

Imports System.CodeDom
Imports System.CodeDom.Compiler
Imports System.Security.Permissions
Imports System.Web.Services.Description
Imports System.Reflection

Public Function CallWebService(ByVal webServiceAsmxUrl As String, _
       ByVal serviceName As String, ByVal methodName As String, _
       ByVal args() As Object) As Object

    Try
    Dim client As System.Net.WebClient = New System.Net.WebClient()

    '-Connect To the web service
    Dim stream As System.IO.Stream = _
        client.OpenRead(webServiceAsmxUrl + "?wsdl")

    'Read the WSDL file describing a service.
    Dim description As ServiceDescription = ServiceDescription.Read(stream)

    'LOAD THE DOM'''''''''''''''''''''''''''

    '--Initialize a service description importer.
    Dim importer As ServiceDescriptionImporter = New ServiceDescriptionImporter()
    importer.ProtocolName = "Soap12" ' Use SOAP 1.2.
    importer.AddServiceDescription(description, Nothing, Nothing)

    '--Generate a proxy client. 

    importer.Style = ServiceDescriptionImportStyle.Client
    '--Generate properties to represent primitive values.
    importer.CodeGenerationOptions = _
         System.Xml.Serialization.CodeGenerationOptions.GenerateProperties

    'Initialize a Code-DOM tree into which we will import the service.
    Dim nmspace As CodeNamespace = New CodeNamespace()
    Dim unit1 As CodeCompileUnit = New CodeCompileUnit()
    unit1.Namespaces.Add(nmspace)

    'Import the service into the Code-DOM tree. 
    'This creates proxy code that uses the service.

    Dim warning As ServiceDescriptionImportWarnings = _
                   importer.Import(nmspace, unit1)

    If warning = 0 Then

            '--Generate the proxy code
            Dim provider1 As CodeDomProvider = _
                      CodeDomProvider.CreateProvider("VB")
            '--Compile the assembly proxy with the // appropriate references
            Dim assemblyReferences() As String
            assemblyReferences = New String() {"System.dll", _
                "System.Web.Services.dll", "System.Web.dll", _
                "System.Xml.dll", "System.Data.dll"}
        	Dim parms As CompilerParameters = New CompilerParameters(assemblyReferences)
	parms.GenerateInMemory = True '(Thanks for this line nikolas)
        	Dim results As CompilerResults = provider1.CompileAssemblyFromDom(parms, unit1)

        '-Check For Errors
        If results.Errors.Count > 0 Then

            Dim oops As CompilerError
            For Each oops In results.Errors
                System.Diagnostics.Debug.WriteLine("========Compiler error============")
                System.Diagnostics.Debug.WriteLine(oops.ErrorText)
            Next
            Throw New System.Exception("Compile Error Occurred calling webservice.")
        End If

        '--Finally, Invoke the web service method
        Dim wsvcClass As Object = results.CompiledAssembly.CreateInstance(serviceName)
        Dim mi As MethodInfo = wsvcClass.GetType().GetMethod(methodName)
        Return mi.Invoke(wsvcClass, args)

    Else
        Return Nothing
    End If

    Catch ex As Exception
    Throw ex
    End Try
End Function

Calling

Call this web service in a Webform or windows form or method, etc... as shown below:

Dim WebserviceUrl As String = _
"http://www.abc.com/lgl/test/webservice/v1_00/security.asmx"

'specify service name
Dim serviceName As String = "SecurityAndSessionManagement"

'specify method name to be called
Dim methodName As String = "Session_Start"

'Arguments passed to the method
Dim arArguments(1) As String
arArguments(0) = "abc"
arArguments(1) = "xxxx"

Dim objCallWS As New DynamicWebService
sSessionID = objCallWS.CallWebService(WebserviceUrl, serviceName, _
                                      methodName, arArguments)
MsgBox("new SessionID: " & sSessionID)

History

• 11^th September, 2009: Initial post