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SoapHttpClientProtocol.Invoke Method

Invokes an XML Web service method synchronously using SOAP.

Namespace:  System.Web.Services.Protocols
Assembly:  System.Web.Services (in System.Web.Services.dll)

'Declaration
Protected Function Invoke ( _
	methodName As String, _
	parameters As Object() _
) As Object()

Parameters

methodName
Type: System.String

The name of the XML Web service method.

parameters
Type: System.Object()

An array of objects that contains the parameters to pass to the XML Web service. The order of the values in the array corresponds to the order of the parameters in the calling method of the derived class.

Return Value

Type: System.Object()
An array of objects that contains the return value and any reference or out parameters of the derived class method.

ExceptionCondition
SoapException

The request reached the server computer, but was not processed successfully.

InvalidOperationException

The request was not valid for the object's current state.

WebException

An error occurred while accessing the network.

Typically, you do not call the Invoke method directly, unless you are building your own proxy class for an XML Web service.

A proxy class generated by the Web Services Description Language tool (Wsdl.exe) for an XML Web service exposes the XML Web service methods as names off of the proxy class. The proxy class calls the Invoke method to invoke an XML Web service method call. For example, if an XML Web service exposes an XML Web service method named Add, the proxy class also contains a method named Add. Within the code for the Add method in the proxy class, a synchronous call is made to the XML Web service method through the Invoke method and then the results are placed into the expected return type for Add.

The methodName parameter is used to find the custom attributes that may have been added to the method, such as SoapDocumentMethodAttribute. SoapDocumentMethodAttribute provides additional information on the derived method which is required for the SOAP protocol.

The following code example is a proxy class generated by Wsdl.exe for the Math XML Web service. Within the Add method of the proxy class, the Invoke method is calling the Add XML Web service method.

Option Strict On 
Option Explicit On 

Imports System
Imports System.Diagnostics
Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.Xml.Serialization

Namespace MyMath

    <System.Web.Services.WebServiceBindingAttribute(Name:="MyMathSoap", [Namespace]:="http://www.contoso.com/")>  _
    Public Class MyMath
        Inherits System.Web.Services.Protocols.SoapHttpClientProtocol

        <System.Diagnostics.DebuggerStepThroughAttribute()>  _
        Public Sub New()
            MyBase.New 
            Me.Url = "http://www.contoso.com/math.asmx" 
        End Sub

        <System.Diagnostics.DebuggerStepThroughAttribute(),  _
         System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://www.contoso.com/Add", RequestNamespace:="http://www.contoso.com/", ResponseNamespace:="http://www.contoso.com/", Use:=System.Web.Services.Description.SoapBindingUse.Literal, ParameterStyle:=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)>  _
        Public Function Add(ByVal num1 As Integer, ByVal num2 As Integer) As Integer 
            Dim results() As Object = Me.Invoke("Add", New Object() {num1, num2})
            Return CType(results(0),Integer)
        End Function

        <System.Diagnostics.DebuggerStepThroughAttribute()>  _
        Public Function BeginAdd(ByVal num1 As Integer, ByVal num2 As Integer, ByVal callback As System.AsyncCallback, ByVal asyncState As Object) As System.IAsyncResult
            Return Me.BeginInvoke("Add", New Object() {num1, num2}, callback, asyncState)
        End Function

        <System.Diagnostics.DebuggerStepThroughAttribute()>  _
        Public Function EndAdd(ByVal asyncResult As System.IAsyncResult) As Integer 
            Dim results() As Object = Me.EndInvoke(asyncResult)
            Return CType(results(0),Integer)
        End Function 
    End Class 
End Namespace

The following code example is the Math XML Web service, from which the preceding proxy class was created.

<%@ WebService Language="VB" Class="MyMath"%>
Imports System.Web.Services
Imports System

<WebService(Namespace:="http://www.contoso.com/")> _
Public Class MyMath
    <WebMethod()> _
    Public Function Add(num1 As Integer, num2 As Integer) As Integer
        Return num1 + num2
    End Function 'Add
End Class 'Math

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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