HttpPostClientProtocol Class

The base class for XML Web service client proxies that use the HTTP-POST protocol.

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

public class HttpPostClientProtocol : HttpSimpleClientProtocol

When an XML Web service client uses the HTTP-POST protocol, by default parameters are encoded within the HTTP body using URL encoding rules and uses plain XML for the response. This protocol uses classes that derive from MimeFormatter to encode parameters and return values into standard MIME formats. The encoders to use are specified in the service description.

If you are building an XML Web service client using ASP.NET, then a proxy class deriving indirectly or directly from WebClientProtocol needs to be created for the XML Web service you want to call. When the XML Web service client is calling using HTTP, derive the proxy class HttpSimpleClientProtocol, which in turn derives from WebClientProtocol.

HttpGetClientProtocol and HttpPostClientProtocol derive from HttpSimpleClientProtocol, providing the support for calling an XML Web service method using HTTP-GET and HTTP-POST respectively. Clients calling an XML Web service using SOAP should derive from SoapHttpClientProtocol.

For details on building a proxy class, see [<topic://cpconcreatingwebserviceproxy>].

The following example is a proxy class generated by the Wsdl.exe utility for the Math XML Web service below. The proxy class derives from HttpPostClientProtocol, which derives from the abstract HttpSimpleClientProtocol class.

using System.Diagnostics;
using System.Xml.Serialization;
using System;
using System.Web.Services.Protocols;
using System.Web.Services;

public class MyMath : System.Web.Services.Protocols.HttpPostClientProtocol {

    public MyMath() {
        this.Url = "";

    [System.Web.Services.Protocols.HttpMethodAttribute(typeof(System.Web.Services.Protocols.XmlReturnReader), typeof(System.Web.Services.Protocols.HtmlFormParameterWriter))]
    [return: System.Xml.Serialization.XmlRootAttribute("int", Namespace="", IsNullable=false)]
    public int Add(string num1, string num2) {
        return ((int)(this.Invoke("Add", (this.Url + "/Add"), new object[] {num1,

    public System.IAsyncResult BeginAdd(string num1, string num2, System.AsyncCallback callback, object asyncState) {
        return this.BeginInvoke("Add", (this.Url + "/Add"), new object[] {num1,
                    num2}, callback, asyncState);

    public int EndAdd(System.IAsyncResult asyncResult) {
        return ((int)(this.EndInvoke(asyncResult)));
#using <mscorlib.dll>
#using <System.Web.Services.dll>
#using <System.Xml.dll>
#using <System.dll>
using namespace System::Diagnostics;
using namespace System::Xml::Serialization;
using namespace System;
using namespace System::Web::Services::Protocols;
using namespace System::Web::Services;

public __gc class MyMath : public System::Web::Services::Protocols::HttpPostClientProtocol {

    MyMath() {
        this->Url = S"";

    [returnvalue: System::Xml::Serialization::XmlRootAttribute(S"int", Namespace=S"", IsNullable=false)]
    int Add(String* num1, String* num2) {
        Object* temp2 [] = {num1, num2};
        return *dynamic_cast<__box int*>(this->Invoke(S"Add", (String::Concat( this->Url, S"/Add" )), temp2));

    System::IAsyncResult* BeginAdd(String* num1, String* num2, System::AsyncCallback* callback, Object* asyncState) {
        Object* temp3 [] = {num1, num2};
        return this->BeginInvoke(S"Add", (String::Concat( this->Url, S"/Add" )), temp3, callback, asyncState);

    int EndAdd(System::IAsyncResult* asyncResult) {
        return *dynamic_cast<__box int*>(this->EndInvoke(asyncResult));

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

<%@ WebService Language="C#" Class="Math"%>
 using System.Web.Services;
 using System;

 public class Math {
      [ WebMethod ]
      public int Add(int num1, int num2) {
          return num1+num2;

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

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