使用asp.net和C＃从JavaScript在外部服务器上调用Web服务

Question

I'm trying to test web service calls using an ASP.NET page that creates a form with username and password fields and a "Submit" button. (Both jQuery and the .js file I'm using are included in script tags in the head element.)

The "Submit" button calls a function created in the C# code behind file that makes a call to a separate JavaScript file.

protected void mSubmit_Click(object sender, EventArgs eventArgs)
{
    String authenticate = String.Format("Authentication(\"{0}\",\"{1}\");", this.mUsername.Text,this.mPassword.Text);
    Page.ClientScript.RegisterStartupScript(this.GetType(), "ClientScript", authenticate, true);
}

The JavaScript function, Authenticate , makes web service call, using jQuery and Ajax, to a different server, sending JSON parameters and expecting back JSON in response.

function Authentication(uname, pwd) {

    //gets search parameters and puts them in json format
    var params = '{"Header":{"AuthToken":null,"ProductID":"NOR","SessToken":null,"Version":1},"ReturnAuthentication":true,"Password":"' + pwd + '","Username":"' + uname + '",”ReturnCredentials”:false }';

    var xmlhttp = $.ajax({
        async: false,
        type: "POST",
        url: 'https://myHost.com/V1/Identity/Authenticate',
        data: params,
        contentType: 'application/json'
    });

    alert(xmlhttp.statusText);
    alert(xmlhttp.responseText);

    return;
}

However, because the web service I'm calling is on a different server than the ASP.NET, C# and JavaScript files, I'm not getting a statusText or responseText alert.

Somehow, nothing is being sent to the web service and I'm not getting anything back, not even an error. I tried putting a function in the beforeSend attribute, but that didn't fire. Is there a special way I need to handle calling an off-server web service?

At the advice of jjnguy, Janie and Nathan, I'm now trying a server side call to the web service using HttpWebRequest. Using some of jjnguy's code as well as code from this question , I've come up with this.

public static void Authenticate(string pwd, string uname)
{
    string ret = null;

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://myhost.com/V1/Identity/Authenticate");
    request.ContentType = "application/json";
    request.Method = "POST";

    string data = "{\"Header\":{\"AuthToken\":null,\"ProductID\":\"NOR\",\"SessToken\":null,\"Version\":1},\"ReturnAuthentication\":true,\"Password\":\"" + pwd + "\",\"Username\":\"" + uname + "\",\"ReturnCredentials\":false }'";

    byte[] byteData = UTF8Encoding.UTF8.GetBytes(data);
    request.ContentLength = byteData.Length;

    using (Stream postStream = request.GetRequestStream()) 
    {
        postStream.Write(byteData, 0, byteData.Length);
    }

    HttpWebResponse response = (HttpWebResponse)request.GetResponse();

    using (response)
    {
        // Get the response stream  
        StreamReader reader = new StreamReader(response.GetResponseStream());

        // Console application output  
        ret = reader.ReadToEnd();
    }

    Console.WriteLine(ret);
}

However, I'm getting a (400) Bad Request error from the remote server when I try to get the response from my HttpWebRequest. The value of the Response property of the exception says {System.Net.HttpWebResponse} and the value of the Status property is ProtocolError . I'm pretty sure this is because the URL is using HTTP SSL protocol. What can I do to get around that, other than having the ASP.NET page URL start with HTTPS (not an option)?

Answer 1

事实证明，我在更新中发布的代码是正确的，我只是有错字和一个错误的数据字符串设置。

    string data = "{\"Header\":{\"AuthToken\":null,\"ProductID\":\"NOR\",\"SessToken\":null,\"Version\":1},\"ReturnAuthentication\":true,\"Password\":\"" + pwd + "\",\"Username\":\"" + uname + "\",\"ReturnCredentials\":true}";

Answer 2

For simplicity's sake, why don't you write the call to the webservice in C# on the Server Side?

You have the same abilities to send requests and get responses in C# as you do with Javascript.

Here is a crack at your function in C#:

public static string Authenticate(string pwd, string uname)
{
    HttpWebRequest requestFile = (HttpWebRequest)WebRequest.Create("https://myHost.com/V1/Identity/Authenticate");
    requestFile.ContentType = "application/json";
    requestFile.Method = "POST";
    StreamWriter postBody = new StreamWriter(requestFile.GetRequestStream())
    using (postBody) {
        postBody.Write("{\"Header\":{\"AuthToken\":null,\"ProductID\":\"NOR\",\"SessToken\":null,\"Version\":1},\"ReturnAuthentication\":true,\"Password\":\"" + pwd + "\",\"Username\":\"" + uname + "\",\"ReturnCredentials\":false }'");
    }
    HttpWebResponse serverResponse = (HttpWebResponse)requestFile.GetResponse();
    if (HttpStatusCode.OK != serverResponse.StatusCode)
        throw new Exception("Url request failed.  Connection to the server inturrupted");
    StreamReader responseStream = new StreamReader(serverResponse.GetResponseStream());
    string ret = null;
    using (responseStream) {
        ret = responseStream.ReadLine();
    }
    return ret;
}

Disclaimer This has not been tested.

Answer 3

Instead of using the client script to make the request from the server; use server side code to make the request

EDIT to expand answer:

From your web project in visual studio, click add web reference, and point to the service you were originally accessing via your client script: (I believe it was ' https://myHost.com/V1/Identity/Authenticate )

You can now talk to the service using c# code instead of js (and pass in the users provided credentials.)

Also, since the request against the service is coming from a server, rather than a browser; you bypass the cross-domain restrictions that apply.

FURTHER EDIT to show additional technique:

If you don't like the idea of using Visual Studio to generate a service proxy for you, then you can handcraft the request yourself using WebClient or HttpRequest

WebClient: http://msdn.microsoft.com/en-us/library/system.net.webclient(VS.80).aspx

HttpWebRequest: http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest(VS.80).aspx

Answer 4

Seems like you're running into the same origin policy

http://en.wikipedia.org/wiki/Same_origin_policy

I believe there are ways to circumvent it, but I think the other posters are right. On the server, write methods that use a HttpWebRequest to call the web service, and then use JavaScriptSerializer to parse out the JSON. I spent most of the afternoon researching this cause I'll have to write something similar myself.

>>>>  Nathan

PS I like @Janie's plan better... Can you do that with a web service that returns JSON as well as one that would pass back XML?