Sys.Net.WebRequest Class

  • Article

Provides client script functionality to make a Web request.

Namespace: Sys.Net

Inherits: None

var wRequest = new Sys.Net.WebRequest();

Constructors

Name

Description

Sys.Net.WebRequest webRequest Constructor

Initializes a new instance of the WebRequest class.

Members

Name

Description

Sys.Net.WebRequest add_completed Method

Registers an event handler to associate with the Web request instance.

Sys.Net.WebRequest completed Method

Raises the completed event for the associated Sys.Net.WebRequest instance.

Sys.Net.WebRequest.getResolvedUrl Method

Gets the resolved URL of the Web request instance.

Sys.Net.WebRequest invoke Method

Issues a network call for the Web request instance.

Sys.Net.WebRequest remove_completed Method

Removes the event handler associated with the Web request instance.

Sys.Net.WebRequest body Property

Gets or sets the HTTP body of the Web request.

Sys.Net.WebRequest executor Property

Gets or sets the executor of the associated Web request instance.

Sys.Net.WebRequest headers Property

Gets the HTTP headers for the Web request.

Sys.Net.WebRequest httpVerb Property

Gets or sets the Web request HTTP verb used to issue the Web request.

Sys.Net.WebRequest timeout Property

Gets or sets the time-out value for the Web request instance.

Sys.Net.WebRequest url Property

Gets or sets the URL of the Web request instance.

Sys.Net.WebRequest userContext Property

Gets or sets the user context associated with the Web request instance.

Remarks

The WebRequest class is used by asynchronous communication layer classes to make a Web request. You typically do not use this type directly in your applications. Instead, from the browser you call Web service methods or static page methods by using proxy methods. For more information, see Exposing Web Services to Clients.

However, you can create and use a WebRequest instance for the following scenarios:

  • When you want to make network requests that are not simple Web service method calls.

  • When you want to set HTTP request properties directly.

  • When you are using a custom executor that is based on the Sys.Net.WebRequestExecutor class.

Example

The following example shows how to create an instance of the WebRequest class to make a GET Web request. The example shows a Web page and the client script used to interact with the WebRequest class.

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">


<html xmlns="https://www.w3.org/1999/xhtml" >
    <head id="Head1" runat="server">

        <title> Using WebRequest </title>

        <style type="text/css">
            body {  font: 11pt Trebuchet MS;
                    font-color: #000000;
                    padding-top: 72px;
                    text-align: center }

            .text { font: 8pt Trebuchet MS }
        </style>


     </head>

   <body>

    <h2>Using WebRequest</h2>

         <form id="form1" runat="server">
            <asp:ScriptManager runat="server" ID="ScriptManagerId">
                <Scripts>
                    <asp:ScriptReference Path="WebRequest.js" />
                </Scripts>
            </asp:ScriptManager>
        </form>










        <table>
            <tr align="left">
                <td>Make GET Request:</td>
                <td>
                    <button id="Button1"  
                        onclick="GetWebRequest()">GET</button>
                </td>
            </tr>
            <tr align="left">  
                <td>Request Body:</td>
                <td>
                    <button id="Button2"  
                        onclick="PostWebRequest()">Body</button>
                </td>
            </tr>
            <tr align="left">
                <td>Request Timeout:</td>
                <td>
                    <button id="Button3"  
                        onclick="WebRequestTimeout()">Timeout</button>
                </td>
            </tr> 
            <tr align="left">
                <td>Request Completed Handler:</td>
                <td>
                    <button id="Button4"  
                        onclick="WebRequestCompleted()">Completed Handler</button>
                </td>
            </tr>
            <tr align="left">
                <td>Resolved Url:</td>
                <td>
                    <button id="Button5"  
                        onclick="GetWebRequestResolvedUrl()">Resolved Url</button>
                </td>
            </tr>
            <tr align="left">
                <td>Request Executor:</td>
                <td>
                    <button id="Button6"  
                        onclick="WebRequestExecutor()">Executor</button>
                </td>
            </tr>
            <tr align="left">
                <td>Request Header:</td>
                <td>
                    <button id="Button7"  
                        onclick="WebRequestHeader()">Header</button>
                </td>
            </tr>
        </table>



        <hr />

        <div id="ResultId" style="background-color:Aqua;"></div>



    </body>

</html>

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">


<html xmlns="https://www.w3.org/1999/xhtml" >
    <head id="Head1" runat="server">

        <title> Using WebRequest </title>

        <style type="text/css">
            body {  font: 11pt Trebuchet MS;
                    font-color: #000000;
                    padding-top: 72px;
                    text-align: center }

            .text { font: 8pt Trebuchet MS }
        </style>

   </head>

   <body>

    <h2>Using WebRequest</h2>

        <form id="form1" runat="server">
            <asp:ScriptManager runat="server" ID="ScriptManagerId">
                <Scripts>
                    <asp:ScriptReference Path="WebRequest.js" />
                </Scripts>
            </asp:ScriptManager>
        </form>









        <table>
            <tr align="left">
                <td>Make GET Request:</td>
                <td>
                    <button id="Button1"  
                        onclick="GetWebRequest()">GET</button>
                </td>
            </tr>
            <tr align="left">  
                <td>Request Body:</td>
                <td>
                    <button id="Button2"  
                        onclick="PostWebRequest()">Body</button>
                </td>
            </tr>
            <tr align="left">
                <td>Request Timeout:</td>
                <td>
                    <button id="Button3"  
                        onclick="WebRequestTimeout()">Timeout</button>
                </td>
            </tr> 
            <tr align="left">
                <td>Request Completed Handler:</td>
                <td>
                    <button id="Button4"  
                        onclick="WebRequestCompleted()">Completed Handler</button>
                </td>
            </tr>
            <tr align="left">
                <td>Resolved Url:</td>
                <td>
                    <button id="Button5"  
                        onclick="GetWebRequestResolvedUrl()">Resolved Url</button>
                </td>
            </tr>
            <tr align="left">
                <td>Request Executor:</td>
                <td>
                    <button id="Button6"  
                        onclick="WebRequestExecutor()">Executor</button>
                </td>
            </tr>
            <tr align="left">
                <td>Request Header:</td>
                <td>
                    <button id="Button7"  
                        onclick="WebRequestHeader()">Header</button>
                </td>
            </tr>
        </table>



        <hr />

        <div id="ResultId" style="background-color:Aqua;"></div>



    </body>

</html>

var getPage;
var postPage;
var displayElement;

function pageLoad()
{
    getPage = "getTarget.htm";
    postPage = "postTarget.aspx";
    displayElement = $get("ResultId");
}

// This function performs a GET Web request 
// to retrieve  information from the Url specified in 
// the query string. 
function GetWebRequest()
{
    alert("Performing Get Web request.");

    // Instantiate the WebRequest object.
    var wRequest =  new Sys.Net.WebRequest();

    // Set the request Url.  
    wRequest.set_url(getPage);  

    // Set the request verb.
    wRequest.set_httpVerb("GET");

    // Set user's context
    wRequest.set_userContext("user's context");

    // Set the web request completed event handler,
    // for processing return data.
    wRequest.add_completed(OnWebRequestCompleted);


    // Clear the results page element.
    displayElement.innerHTML = "";

    // Execute the request.
    wRequest.invoke();  

}

// This function performs a POST Web request
// to upload information to the resource 
// identified by the Url. 
function PostWebRequest()
{
    // Instantiate the WebRequest object.
    var wRequest =  new Sys.Net.WebRequest();

    // Set the request Url.  
    wRequest.set_url(postPage); 

    // Set the request verb.
    wRequest.set_httpVerb("POST");

    var body = "Message=Hello! Do you hear me?"
    wRequest.set_body(body);
    wRequest.get_headers()["Content-Length"] = body.length;


    // Set the web request completed event handler,
    // for processing return data.
    wRequest.add_completed(OnWebRequestCompleted);

    // Clear the results page element.
    displayElement.innerHTML = "";

    // Execute the request.
    wRequest.invoke();  
}

// This function adds and removes the 
// Web request completed event handler.
function WebRequestCompleted()
{
    // Instantiate the WebRequest.
    var wRequest =  new Sys.Net.WebRequest();

    // Set the request Url.  
    wRequest.set_url(getPage);  

    // Set the web request completed event handler,
    // for processing return data.
    wRequest.add_completed(OnWebRequestCompleted);   
    alert("Added Web request completed handler");

    // Remove the web request completed event handler.
    // Comment the following two lines if you want to
    // use the handler.
    wRequest.remove_completed(OnWebRequestCompleted); 
    alert("Removed handler; the Web request return is not processed.");

    // Execute the request.
    wRequest.invoke();  
}

// This function gets the resolved Url 
// of the Web request instance.
function GetWebRequestResolvedUrl()
{
    // Instantiate the WebRequest.
    var wRequest =  new Sys.Net.WebRequest();

    // Set the request Url.  
    wRequest.set_url(getPage);  

    // Get the web request completed event handler.
    var resUrl = wRequest.getResolvedUrl();   
    alert("Resolved Url: " + resUrl);

    // Set the web request completed event handler,
    // for processing return data.
    wRequest.add_completed(OnWebRequestCompleted); 

    // Execute the request.
    wRequest.invoke();  

}


// This function gets and sets the 
// Web request time out.
function WebRequestTimeout()
{    
    // Instantiate the WebRequest.
    var wRequest =  new Sys.Net.WebRequest();

    // Set the request Url.  
    wRequest.set_url(getPage);  

    var defaultTimeout =  
        wRequest.get_timeout();

    // Set request timeout to 100 msec.
    wRequest.set_timeout(100);

    var newTimeout = 
        wRequest.get_timeout();

    alert("Default timeout: " + defaultTimeout);
    alert("New timeout: " + newTimeout);

    // Set the web request completed event handler,
    // for processing return data.
    wRequest.add_completed(OnWebRequestCompleted);   

    // Execute the request.
    wRequest.invoke();     
}


// This function sets the Web request
// executor, replacing the default one.
function WebRequestExecutor()
{    
    // Instantiate the WebRequest.
    var wRequest =  new Sys.Net.WebRequest();

    // Create the executor. In this case it is an
    // XMLHttpExecutor, equivalent to the default
    // executor. But, you can create a custom one.
    var executor = new Sys.Net.XMLHttpExecutor();

    // Set the executor, replacing the default one. 
    // In this case the executor is equivalent to the
    // default one.
    wRequest.set_executor(executor); 

    // Get the current executor       
    var executor =  
        wRequest.get_executor();

    alert("Response availabe: " + executor.get_responseAvailable())
}

 // This function sets an HTTP header for
 // the Web request.
 function WebRequestHeader() 
 {
       // Instantiate the WebRequest object.
    var wRequest =  new Sys.Net.WebRequest();

    // Set the request Url.  
    wRequest.set_url(postPage); 

    // Set the request verb.
    wRequest.set_httpVerb("POST");

    var body = "Message=Hello! Do you hear me?"
    wRequest.set_body(body);

    // Set the value of the HTTP header's "Content-Length".
    wRequest.get_headers()["Content-Length"] = body.length;

    // Set the web request completed event handler,
    // for processing return data.
    wRequest.add_completed(OnWebRequestCompletedHeader);

    // Clear the results page element.
    displayElement.innerHTML = "";

    // Execute the request.
    wRequest.invoke();  
}

// This the handler for the Web request completed event
// that is used to display return data.
function OnWebRequestCompleted(executor, eventArgs) 
{
    if(executor.get_responseAvailable()) 
    {

        // Clear the previous results. 
        displayElement.innerHTML = "";

        // Display Web request status.                  
        DisplayWebRequestStatus(executor);

        // Display Web request headers.                  
        DisplayWebRequestHeaders(executor);

        // Display Web request body.                  
        DisplayWebRequestBody(executor);

    }
    else
    {
        if (executor.get_timedOut())
            alert("Timed Out");
        else
            if (executor.get_aborted())
                alert("Aborted");
    }
}


// This the handler for the Web request completed event
// that is used to display header information.
function OnWebRequestCompletedHeader(executor, eventArgs) 
{
    if(executor.get_responseAvailable()) 
    {

        // Clear the previous results. 
         displayElement.innerHTML = "";

        // Display Web request headers.                  
        DisplayWebRequestHeaders(executor);

    }
    else
    {

        if (executor.get_timedOut())
            alert("Timed Out");

        else

            if (executor.get_aborted())
                alert("Aborted");

    }
}

// This function is used to display the Web request status.
function DisplayWebRequestStatus(executor)
{
     displayElement.innerHTML +=
     "Status: [" + 
     executor.get_statusCode() + " " + 
     executor.get_statusText() + "]" + "<br/>"
}

// This function is used to display Web request HTTP headers.
function DisplayWebRequestHeaders(executor)
{
    displayElement.innerHTML += 
        "Headers: ";
    displayElement.innerHTML += 
        executor.getAllResponseHeaders() + "<br/>";
 }

// This function is used to display the Web request body.
function DisplayWebRequestBody(executor)
{   
     displayElement.innerHTML += 
        "Body: ";
    if (document.all)
         displayElement.innerText += 
            executor.get_responseData();
    else
        // Firefox
         displayElement.textContent += 
            executor.get_responseData();
}

// This function is used to display the Web request message.
function DisplayInformation(message)
{
    // Clear the previous results.
     displayElement.innerHTML = "";
    // Display information.
    displayElement.innerHTML = "<br/>" + message;
}

if (typeof(Sys) !== "undefined") Sys.Application.notifyScriptLoaded();

See Also

Reference

Sys.Net.XMLHttpExecutor Class

Sys.Net.WebRequestManager Class