I have the following C# class which initiates an HTTP request from a Windows Phone to a server:
public class Request
{
public string data;
public string result;
public Request()
{
}
public void doRequest(string parameters, string URL)
{
data = parameters;
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(URL);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.BeginGetRequestStream(new AsyncCallback(GetRequestStreamCallback), request);
}
public void GetRequestStreamCallback(IAsyncResult callbackResult)
{
HttpWebRequest myRequest = (HttpWebRequest)callbackResult.AsyncState;
Stream postStream = myRequest.EndGetRequestStream(callbackResult);
byte[] byteArray = Encoding.UTF8.GetBytes(data);
postStream.Write(byteArray, 0, byteArray.Length);
postStream.Close();
myRequest.BeginGetResponse(new AsyncCallback(GetResponsetStreamCallback), myRequest);
}
public void GetResponsetStreamCallback(IAsyncResult callbackResult)
{
HttpWebRequest request = (HttpWebRequest)callbackResult.AsyncState;
HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(callbackResult);
StreamReader httpWebStreamReader = new StreamReader(response.GetResponseStream());
result = httpWebStreamReader.ReadToEnd();
}
Now, in my main class, I call the doRequest method to do an HTTP request from the Windows Phone:
Request req = new Request();
req.doRequest("function=LogIn&username=" + username + "&password=" + password, "http://localhost:4000/Handler.ashx");
When calling this method, how can I get the result (the result variable) from the server since it is received in the GetResponsetStreamCallback method and not in the doRequest method?
You have several possibilities. One would be to define property to make the result accessible outside. Define
public class Request
{
public string Result
{
get{
if(result != null && !string.IsNullOrEmpty(result))
return result;
return null;
}
}
...
}
You might create an event and have objects subscribe to it, so you can notice them when the asynchronous request has ended. Or make your calls synchronous, which is a little easier to do, as you don't have synchronize your calls and the requests from other objects.
Related
I am writing a Windows Phone 8 app that is supposed to send an GET+POST request to a server and parse the answer.
The code I am using to send the request and to get a response back is the following (it is written in a separate static class):
// server to POST to
string url = "http://myserver.com/?page=hello¶m2=val2";
// HTTP web request
var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
httpWebRequest.ContentType = "application/x-www-form-urlencoded";
httpWebRequest.Method = "POST";
// Write the request Asynchronously
using (var stream = await Task.Factory.FromAsync<Stream>(httpWebRequest.BeginGetRequestStream,
httpWebRequest.EndGetRequestStream, null))
{
// Create the post data
string postData = "pseudo=pseudo&titre=test&texte=\"Contenu du message\"";
byte[] byteArray = Encoding.UTF8.GetBytes(postData);
// Write the bytes to the stream
await stream.WriteAsync(byteArray, 0, byteArray.Length);
stream.Close();
IAsyncResult ar = httpWebRequest.BeginGetResponse(new AsyncCallback(GetResponsetStreamCallback), httpWebRequest);
}
}
private static void GetResponsetStreamCallback(IAsyncResult callbackResult)
{
HttpWebRequest request = (HttpWebRequest)callbackResult.AsyncState;
HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(callbackResult);
using (StreamReader httpWebStreamReader = new StreamReader(response.GetResponseStream()))
{
string result = httpWebStreamReader.ReadToEnd();
//For debug: show results
System.Diagnostics.Debug.WriteLine(result);
}
My problem is : I have no idea how to get this answer (the string result) back in my behind-code in my app (or any other method in my app to be honest).
How could I do that?
You can try the following code,
string url = "http://myserver.com/?page=hello¶m2=val2";
// HTTP web request
var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
httpWebRequest.ContentType = "application/x-www-form-urlencoded";
httpWebRequest.Method = "POST";
httpWebRequest.BeginGetRequestStream(new AsyncCallback(GetRequestStreamCallback), webRequest);
}
private void GetRequestStreamCallback(IAsyncResult asynchronousResult)
{
HttpWebRequest webRequest = (HttpWebRequest)asynchronousResult.AsyncState;
using (var postStream = webRequest.EndGetRequestStream(asynchronousResult))
{
//send yoour data here
}
webRequest.BeginGetResponse(new AsyncCallback(GetResponseCallback), webRequest);
}
void GetResponseCallback(IAsyncResult asynchronousResult)
{
try
{
HttpWebRequest myrequest = (HttpWebRequest)asynchronousResult.AsyncState;
using (HttpWebResponse response = (HttpWebResponse)myrequest.EndGetResponse(asynchronousResult))
{
System.IO.Stream responseStream = response.GetResponseStream();
using (var reader = new System.IO.StreamReader(responseStream))
{
data = reader.ReadToEnd();
}
responseStream.Close();
}
}
catch (Exception e)
{
//Handle Exception
}
else
throw;
}
}
public static string GetPageAsString(Uri address)
{
string result = "";
// Create the web request
HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;
// Get response
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
// Get the response stream
StreamReader reader = new StreamReader(response.GetResponseStream(), Constants.EncodingType);
// Read the whole contents and return as a string
result = reader.ReadToEnd();
}
return result;
}
Does it have to be a static class? Because if you have a new webrequest object for each request, then each response will come back into it's own object.v
You need to put the result somewhere that you can access it from the place you want to use it.
e.g. if you put it into another public static variable member then you can read it off where you need to. But you probably need to signal the UI to action it, or bind it to the UI.
If you use a static place to store it, then you will only have one active at a time. Unless you add it to a static list of items or results that you are working with
See also: http://blogs.msdn.com/b/devfish/archive/2011/04/07/httpwebrequest-fundamentals-windows-phone-services-consumption-part-2.aspx
You can: make a global variable in App.xaml.cs:
public string result;
In code use it as
(App.Current as App).result = httpWebStreamReader.ReadToEnd();
If you will need to get notified in your current active page when the result is updated - use delegates after you get the response which will signal to your page.
Hello I have this code below in which I connected through webservice cz.mfcr.adisrws (pictured) and I need to get some of these values according to what was called in CreateSoapEnvelope()
with this code:
namespace spolehlivost_platce
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
CallWebService();
}
private void Form1_Load(object sender, EventArgs e)
{
}
public static XmlDocument CreateSoapEnvelope()
{
XmlDocument soapEnvelop = new XmlDocument();
soapEnvelop.LoadXml
(#"<soapenv:Envelope xmlns:soapenv=""http://schemas.xmlsoap.org/soap/envelope/""><soapenv:Body><StatusNespolehlivyPlatceRequest xmlns=""http://adis.mfcr.cz/rozhraniCRPDPH/""><dic>28156609</dic></StatusNespolehlivyPlatceRequest></soapenv:Body></soapenv:Envelope>");
return soapEnvelop;
}
protected virtual WebRequest CreateRequest(ISoapMessage soapMessage)
{
var wr = WebRequest.Create(soapMessage.Uri);
wr.ContentType = "text/xml;charset=utf-8";
wr.ContentLength = soapMessage.ContentXml.Length;
wr.Headers.Add("SOAPAction", soapMessage.SoapAction);
wr.Credentials = soapMessage.Credentials;
wr.Method = "POST";
wr.GetRequestStream().Write(Encoding.UTF8.GetBytes(soapMessage.ContentXml), 0, soapMessage.ContentXml.Length);
return wr;
}
private static HttpWebRequest CreateWebRequest(string url, string action)
{
HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(url);
webRequest.Headers.Add("SOAPAction", action);
webRequest.ContentType = "text/xml;charset=\"utf-8\"";
webRequest.Accept = "text/xml";
webRequest.Method = "POST";
return webRequest;
}
private static void InsertSoapEnvelopeIntoWebRequest(XmlDocument soapEnvelopeXml, HttpWebRequest webRequest)
{
using (Stream stream = webRequest.GetRequestStream())
{
soapEnvelopeXml.Save(stream);
}
}
public static void CallWebService()
{
var _url = "http://schemas.xmlsoap.org/soap/envelope/"; //issue
var _action = cz.mfcr.adisrws.InformaceOPlatciType(); //issue
XmlDocument soapEnvelopeXml = CreateSoapEnvelope();
HttpWebRequest webRequest = CreateWebRequest(_url,_action);
InsertSoapEnvelopeIntoWebRequest(soapEnvelopeXml, webRequest);
// begin async call to web request.
IAsyncResult asyncResult = webRequest.BeginGetResponse(null, null);
// suspend this thread until call is complete. You might want to
// do something usefull here like update your UI.
asyncResult.AsyncWaitHandle.WaitOne();
// get the response from the completed web request.
string soapResult;
using (WebResponse webResponse = webRequest.EndGetResponse(asyncResult))
{
using (StreamReader rd = new StreamReader(webResponse.GetResponseStream()))
{
soapResult = rd.ReadToEnd();
}
Console.WriteLine(soapResult);
}
}
I dont know what should be in this line:
var _url = "http://schemas.xmlsoap.org/soap/envelope/"; //issue
var _action = cz.mfcr.adisrws.InformaceOPlatciType(); //issue
May someone help me solve this out?
Thanks in advance.
I receive this exception:
The remote server returned an error: (405) Method Not Allowed
I followed this tutorial.
The _url is the URL of the service - it is the URL (the 'address') where you're hosting your service - if you're hosting it yourself, it should probably be something like:
_url = "http://localhost/MyService/MyService.asmx"
or if you're using the service that somebody else already hosted, then you have to see the URL they provided for it, and put that value in. The value you're currently using (http://schemas.xmlsoap.org/soap/envelope/) is just a layout of the schema for the data, not the actual URL, and esp. not the service itself (it's maybe confusing because of the http, but it's just a way of 'describing' data)
The _action part - that's the method on the service that you're trying to call, and that should also be a string, for example:
_action = "http://localhost/MyService/MyService.asmx?op=HelloWorld"
You have to think about what you are trying to achieve and who-does-what-and-where...
I have the following class (I take it from an example on the net, the only thing I've modified is that I use an IP address and port instead of a domain name):
public class ConnectionManager
{
private static ManualResetEvent allDone = new ManualResetEvent(false);
private string message = "foobar";
public Action MessageSent;
public Action<string> MessageReceived;
public void SendMessage()
{
// Create a new HttpWebRequest object.
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://10.1.91.48:3330/");
request.ContentType = "application/json; charset=utf-8";
request.Accept = "application/json";
// Set the Method property to 'POST' to post data to the URI.
request.Method = "POST";
// start the asynchronous operation
request.BeginGetRequestStream(new AsyncCallback(GetRequestStreamCallback), request);
MessageSent();
// Keep the main thread from continuing while the asynchronous
// operation completes. A real world application
// could do something useful such as updating its user interface.
allDone.WaitOne();
}
private void GetRequestStreamCallback(IAsyncResult asynchronousResult)
{
HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
// End the operation
Stream postStream = request.EndGetRequestStream(asynchronousResult);
// Convert the string into a byte array.
byte[] byteArray = Encoding.UTF8.GetBytes(message);
// Write to the request stream.
postStream.Write(byteArray, 0, byteArray.Length);
postStream.Close();
// Start the asynchronous operation to get the response
request.BeginGetResponse(new AsyncCallback(GetResponseCallback), request);
}
private void GetResponseCallback(IAsyncResult asynchronousResult)
{
HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
// End the operation
HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult);
Stream streamResponse = response.GetResponseStream();
StreamReader streamRead = new StreamReader(streamResponse);
string responseString = streamRead.ReadToEnd();
Console.WriteLine(responseString);
// Close the stream object
streamResponse.Close();
streamRead.Close();
// Release the HttpWebResponse
response.Close();
allDone.Set();
MessageReceived(responseString);
}
}
The code above fails to send the message. If I step, when I'm inside GetRequestStreamCallback I can see inside IAsyncResult the following error:
AsyncWaitHandle = 'asynchronousResult.AsyncWaitHandle' threw an
exception of type 'System.NotSupportedException'
What am I doing wrong? How can I fix this code?
While it's probably not the solution to your problem, you need to get into the habit of placing your IDisposable objects into using blocks, to ensure they get cleaned up even if exceptions happen:
private void GetRequestStreamCallback(IAsyncResult asynchronousResult)
{
HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
// End the operation
using (Stream postStream = request.EndGetRequestStream(asynchronousResult))
{
byte[] byteArray = Encoding.UTF8.GetBytes(message);
// Write to the request stream.
postStream.Write(byteArray, 0, byteArray.Length);
postStream.Close();
}
// Start the asynchronous operation to get the response
request.BeginGetResponse(new AsyncCallback(GetResponseCallback), request);
}
private void GetResponseCallback(IAsyncResult asynchronousResult)
{
HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
// End the operation
string responseString;
using (HttpWebResponse response = (HttpWebResponse) request.EndGetResponse(asynchronousResult))
{
using (Stream streamResponse = response.GetResponseStream())
{
using (StreamReader streamRead = new StreamReader(streamResponse))
{
responseString = streamRead.ReadToEnd();
Console.WriteLine(responseString);
}
}
}
allDone.Set();
MessageReceived(responseString);
}
As an alternative you could be using RestSharp.
http://restsharp.org/
It makes this sort of thing a lot more trivial. You have to make some slight changes to get it to work on the Windows Phone though:
http://www.tonicodes.net/blog/async-and-restsharp-for-windows-phone-7/
Nothing too crazy.
I ended up using WebClient:
WebClient wc = new WebClient();
wc.DownloadStringCompleted += ReadServerResponse;
wc.DownloadStringAsync(new Uri(url));
Im trying to use HttpWebRequest on a WP7 application, but I have a problem. I never get a response from server :/
What am I doing wrong?
Here is the faulty code peace...
Util Class
public class RequestState
{
// This class stores the State of the request.
const int BUFFER_SIZE = 1024;
public string requestData;
public byte[] Data
{
get
{
ASCIIEncoding ascii = new ASCIIEncoding();
byte[] encodedPostData = ascii.GetBytes(this.requestData);
return encodedPostData;
}
}
public byte[] BufferRead;
public HttpWebRequest request;
public HttpWebResponse response;
public RequestState()
{
BufferRead = new byte[BUFFER_SIZE];
requestData = string.Empty;
request = null;
}
}
The method...
private static ManualResetEvent allDone = new ManualResetEvent(false);
private static string PostRequest(string service, string email, string password, string source)
{
// Prepare request.
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(clientLoginUrl);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
// Create an instance of the RequestState and assign the previous myHttpWebRequest1
// object to it's request field.
RequestState myRequestState = new RequestState();
myRequestState.request = request;
myRequestState.requestData = String.Format(postData, service, email, password, source);
// Get the response that will contain the Auth token.
try
{
request.BeginGetRequestStream(new AsyncCallback(GetRequestStreamCallback), myRequestState);
}
catch (WebException ex)
{
HttpWebResponse faultResponse = ex.Response as HttpWebResponse;
if (faultResponse != null && faultResponse.StatusCode == HttpStatusCode.Forbidden)
throw new IncorrectUsernameOrPasswordException(faultResponse.StatusCode, faultResponse.StatusDescription);
else
throw;
}
// Keep the main thread from continuing while the asynchronous
allDone.WaitOne();
if (myRequestState.response != null)
{
// Check for login failed.
if (myRequestState.response.StatusCode != HttpStatusCode.OK)
throw new LoginFailedException(myRequestState.response.StatusCode, myRequestState.response.StatusDescription);
// Read.
using (StreamReader reader = new StreamReader(myRequestState.response.GetResponseStream()))
return reader.ReadToEnd();
}
else
return string.Empty;
}
private static void GetRequestStreamCallback(IAsyncResult asynchronousResult)
{
RequestState requestState = (RequestState)asynchronousResult.AsyncState;
HttpWebRequest request = (HttpWebRequest)requestState.request;
// End the operation
Stream postStream = request.EndGetRequestStream(asynchronousResult);
// Write to the request stream.
postStream.Write(requestState.Data, 0, requestState.requestData.Length);
postStream.Close();
// Start the asynchronous operation to get the response
request.BeginGetResponse(new AsyncCallback(GetResponseCallback), requestState);
}
private static void GetResponseCallback(IAsyncResult asynchronousResult)
{
RequestState requestState = (RequestState)asynchronousResult.AsyncState;
HttpWebRequest request = (HttpWebRequest)requestState.request;
// End the operation
HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult);
requestState.response = response;
allDone.Set();
}
Have you tried do a request to several different websites without luck?
I had this problem as well, and that was because I missed some header options to the request.
Try download a plugin for etc Mozilla that can sniff your request from the browser to the website, and then add those headers from the request to your headers in the HttpWebRequest.
I'm a little confused. I'm trying to post to my web service in an async manner, ideally I want to start the request, show a loading spinner on the UI and then when the async request finishes process the response and either show an error if there is one, or do another operation with the result.
Here is my code, I call the request here and pass some data in.
private void SignInExecute()
{
if (Username == null || Password == null)
{
LoginOutput = "Please provide a username or password.";
}
else
{
this.webService.SendLoginRequest("http://localhost:3000/client_sessions", "username=" + Username + "&password=" + Password);
}
}
And here is the actual web request code:
public void SendLoginRequest(string url, string postdata)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.Accept = "application/json";
byte[] byteArray = Encoding.UTF8.GetBytes(postdata);
request.CookieContainer = new CookieContainer();
request.ContentLength = byteArray.Length;
Stream dataStream = request.GetRequestStream();
dataStream.Write(byteArray, 0, byteArray.Length);
dataStream.Close();
((HttpWebRequest)request).KeepAlive = false;
request.BeginGetResponse(new AsyncCallback(GetLoginResponseCallback), request);
}
private static void GetLoginResponseCallback(IAsyncResult asynchronousResult)
{
HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
// End the operation
HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult);
Stream streamResponse = response.GetResponseStream();
StreamReader streamRead = new StreamReader(streamResponse);
string responseString = streamRead.ReadToEnd();
Console.WriteLine(responseString);
// Close the stream object
streamResponse.Close();
streamRead.Close();
response.Close();
}
So to sum up. I want to be able to return the response back to the object which originally gave the call for the web request to start. Any help?
You need to tell the BeginGetResponse to go back to the same context in which it was called via SynchronizationContext.Current. Something like this (the code does not have proper error checking, so you should think about that properly) (Also, Platinum Azure is correct that you should use a using to let your streams close properly (and guaranteed):
In your SendLoginRequest:
//Box your object state with the current thread context
object[] boxedItems = new []{request, SynchronizationContext.Current};
request.BeginGetResponse(new AsyncCallback(GetLoginResponseCallback),
boxedItems);
The getresponse code:
private static void GetLoginResponseCallback(IAsyncResult asynchronousResult)
{
//MY UPDATE
//Unbox your object state with the current thread context
object[] boxedItems = asynchronousResult.AsyncState as object[];
HttpWebRequest request = boxedItems[0] as HttpWebRequest;
SynchronizationContext context = boxedItems[1] as SynchronizationContext;
// End the operation
using(HttpWebResponse response =
(HttpWebResponse)request.EndGetResponse(asynchronousResult))
{
using(Stream streamResponse = response.GetResponseStream())
{
using(StreamReader streamRead = new StreamReader(streamResponse))
{
string responseString = streamRead.ReadToEnd();
Console.WriteLine(responseString);
//MY UPDATE
//Make an asynchronous call back onto the main UI thread
//(context.Send for a synchronous call)
//Pass responseString as your method parameter
//If you have more than one object, you will have to box again
context.Post(UIMethodToCall, responseString);
}
}
}
}
To implement your UI processing
public static void UIMethodCall(object ObjectState)
{
String response = ObjectState as String;
label1.Text = String.Format("Output: {0}", response);
//Or whatever you need to do in the UI...
}
Now, I would test this out first, though. My understanding of Microsoft's implementation of event driven async was that the response was context-aware, and knew which context to return to. So, before jumping to the assumption that you are not on the same context, test it out by trying to update the UI (this will cause a thread context exception if you are not on the calling (UI) thread)