Develop Reference

Http Post for Windows Phone 8

I am new to C# so I was wondering if someone can help me out on this. I am trying to send HttpPost from Windows Phone 8 to the server. I found two examples that I would like to combine.
The first one is an example of sending Http Post (http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.begingetrequeststream.aspx). The problem with this one is that it is not support by Windows Phone 8.
The second example is using the BeginGetResponse (http://msdn.microsoft.com/en-us/library/windowsphone/develop/system.net.httpwebrequest(v=vs.105).aspx). This supports windows phone 8.
I need to convert the second example into a BeginGetRequestStream() like the first example. I will try to figure out this myself, but I am posting online if someone already knows how to do this. I am sure this will be helpful for other WP8 developers.
Update
I am now trying to get response from the server. I have started a new question. Please follow this link (Http Post Get Response Error for Windows Phone 8)

I am also currently working on a Windows Phone 8 project and here is how I am posting to a server. Windows Phone 8 sort of has limited access to the full .NET capabilities and most guide I read say you need to be using the async versions of all the functions.
// server to POST to
string url = "myserver.com/path/to/my/post";
// HTTP web request
var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
httpWebRequest.ContentType = "text/plain; charset=utf-8";
httpWebRequest.Method = "POST";
// Write the request Asynchronously
using (var stream = await Task.Factory.FromAsync<Stream>(httpWebRequest.BeginGetRequestStream,
httpWebRequest.EndGetRequestStream, null))
{
//create some json string
string json = "{ \"my\" : \"json\" }";
// convert json to byte array
byte[] jsonAsBytes = Encoding.UTF8.GetBytes(json);
// Write the bytes to the stream
await stream.WriteAsync(jsonAsBytes, 0, jsonAsBytes.Length);
}

I propose a more generic asynchronous approach supporting success and error callbacks here:
//Our generic success callback accepts a stream - to read whatever got sent back from server
public delegate void RESTSuccessCallback(Stream stream);
//the generic fail callback accepts a string - possible dynamic /hardcoded error/exception message from client side
public delegate void RESTErrorCallback(String reason);
public void post(Uri uri, Dictionary<String, String> post_params, Dictionary<String, String> extra_headers, RESTSuccessCallback success_callback, RESTErrorCallback error_callback)
{
HttpWebRequest request = WebRequest.CreateHttp(uri);
//we could move the content-type into a function argument too.
request.ContentType = "application/x-www-form-urlencoded";
request.Method = "POST";
//this might be helpful for APIs that require setting custom headers...
if (extra_headers != null)
foreach (String header in extra_headers.Keys)
try
{
request.Headers[header] = extra_headers[header];
}
catch (Exception) { }
//we first obtain an input stream to which to write the body of the HTTP POST
request.BeginGetRequestStream((IAsyncResult result) =>
{
HttpWebRequest preq = result.AsyncState as HttpWebRequest;
if (preq != null)
{
Stream postStream = preq.EndGetRequestStream(result);
//allow for dynamic spec of post body
StringBuilder postParamBuilder = new StringBuilder();
if (post_params != null)
foreach (String key in post_params.Keys)
postParamBuilder.Append(String.Format("{0}={1}&", key, post_params[key]));
Byte[] byteArray = Encoding.UTF8.GetBytes(postParamBuilder.ToString());
//guess one could just accept a byte[] [via function argument] for arbitrary data types - images, audio,...
postStream.Write(byteArray, 0, byteArray.Length);
postStream.Close();
//we can then finalize the request...
preq.BeginGetResponse((IAsyncResult final_result) =>
{
HttpWebRequest req = final_result.AsyncState as HttpWebRequest;
if (req != null)
{
try
{
//we call the success callback as long as we get a response stream
WebResponse response = req.EndGetResponse(final_result);
success_callback(response.GetResponseStream());
}
catch (WebException e)
{
//otherwise call the error/failure callback
error_callback(e.Message);
return;
}
}
}, preq);
}
}, request);
}

HTTPS web request failing

When I run the program contained below the first HTTPS request succeeds, but the second request fails. Both url's are valid and both can be accessed successfully in a browser. Any suggestions as to what needs to be done to access the second url successfully?
using System;
using System.IO;
using System.Net;
public class Program
{
private static void Main(string[] args)
{
var content = "";
bool status;
var url1 = "https://mail.google.com";
var url2 = "https://my.ooma.com";
status = DoHttpRequest(url1, out content);
OutputStatus(url1, status, content);
status = DoHttpRequest(url2, out content);
OutputStatus(url2, status, content);
Console.ReadLine();
}
private static void OutputStatus(string url, bool status, string content)
{
if (status) Console.WriteLine("Url={0}, Status=Success, content length = {1}", url, content.Length);
else Console.WriteLine("Url={0}, Status=Fail, ErrorMessage={1}", url, content);
}
private static bool DoHttpRequest(string url, out string content)
{
content = "";
var request = (HttpWebRequest) WebRequest.Create(url);
try
{
request.Method = "GET";
request.CookieContainer = null;
request.Timeout = 25000; // 25 seconds
var response = (HttpWebResponse) request.GetResponse();
var streamReader = new StreamReader(response.GetResponseStream());
content = streamReader.ReadToEnd();
return true;
}
catch (WebException ex)
{
content = ex.Message;
return false;
}
}
}

Historically, most problems of this description that I've seen occur when you forget to call .Close() on the object returned from GetResponseStream(). The problem exists because when you forget to close the first request, the second request deadlocks waiting for a free connection.
Typically this hang happens on the 3rd request, not the second.
Update: Looking at your repro, this has nothing to do with the order of the requests. You're hitting a problem because this site is sending a TLS Warning at the beginning of the HTTPS handshake, and .NET will timeout when that occurs. See http://blogs.msdn.com/b/fiddler/archive/2012/03/29/https-request-hangs-.net-application-connection-on-tls-server-name-indicator-warning.aspx. The problem only repros on Windows Vista and later, because the warning is related to a TLS extension that doesn't exist in the HTTPS stack on WinXP.

Increse your request TimeOut.
request.Timeout = 60000; //60 second.
May be your network connection is a bit slow. I run with 25 seconds, okay. (Yeah, the second url is a bit longer to get response, than the first one.)

NullReferenceException reading from an asynchronous HttpWebRequest stream

I'm programming an application for Windows Phone 7. This application firstly sends, and then receives data from a server via HttpWebRequest. Most times it works fine, but sometimes, after receiving a portion of the data properly, I get a NullReferenceException in Stream.Read() function.
The communication starts when the user presses a button. Then I create the HttpWebRequest:
HttpWebRequest request = (HttpWebRequest) WebRequest.Create(sUri);
request.Method = "POST";
request.BeginGetRequestStream(GetRequestStreamCallback, request);
The request callback method:
private void GetRequestStreamCallback(IAsyncResult asynchronousResult)
{
HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
postStream = request.EndGetRequestStream(asynchronousResult);
this.bSyncOK = Send(); //This is my method to send data to the server
postStream.Close();
if (this.bSyncOK)
request.BeginGetResponse(GetResponseCallback, request);
else
manualEventWait.Set(); //This ManualResetEvent notify a thread the end of the communication, then a progressbar must be hidden
}
The response callback method:
private void GetResponseCallback(IAsyncResult asynchronousResult)
{
HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
using (HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult) )
{
using (streamResponse = new StreamReader(response.GetResponseStream() ) )
{
this.bSyncOK = Recv(); //This is my generic method to receive the data
streamResponse.Close();
}
response.Close();
}
manualEventWait.Set(); //This ManualResetEvent notify a thread the end of the communication, then a progressbar must be hidden
}
And finally, this is the code where I get the exception reading the stream data:
int iBytesLeidos;
byte[] byteArrayUTF8 = new byte[8];
iBytesLeidos = streamResponse.BaseStream.Read(byteArrayUTF8, 0, 8); //NullReferenceException!!! -Server always send 8 bytes here-
When the application starts, I create a background thread that frequently sends info to the server. Background and Manual communications can run simultaneously. Could this be a problem?
Thanks.

If streamResponse is global variable, it can cause the problem in a case of an access from another thread. Pass your Stream to the Recv as a parameter
using (StreamReader streamResponse = new StreamReader(response.GetResponseStream() ) )
{
this.bSyncOK = Recv(streamResponse); //This is my generic method to receive the data
streamResponse.Close();
}

Where is your streamResponse declared in latter snippet? Is it the same object as in 3d snippet? Maybe you just use another variable, instead of actual stream.

in the second snippet, try to delete "postStream.Close();".

JSON Data posted by Silverlight is not reaching the server

I have a web client I'm creating in Silverlight. I am trying to get it to communicate it with my web services on my server through GET and POST requests and JSON. The GET requests work fine and I'm able to parse the JSON on the Silverlight end. The POST requests however dont seem to work. The server reads that there is a POST request, but the POST array is empty.
Ive tried two pieces of code to send the POST requests, but both are resulting in the same response - an empty array.
The first Silverlight code I tried was:
public MainPage()
{
InitializeComponent();
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(new Uri("http://www.dipzo.com/game/services.php"));
request.Method = "POST";
request.ContentType = "application/json";
request.BeginGetRequestStream(new AsyncCallback(OnGetRequestStreamCompleted), request);
}
private void OnGetRequestStreamCompleted(IAsyncResult ar)
{
HttpWebRequest request = (HttpWebRequest)ar.AsyncState;
using (StreamWriter writer = new StreamWriter(request.EndGetRequestStream(ar)))
{
writer.Write("name=david");
}
request.BeginGetResponse(new AsyncCallback(OnGetResponseCompleted), request);
}
private void OnGetResponseCompleted(IAsyncResult ar)
{
//this.GetResponseCoimpleted.Visibility = Visibility.Visible;
// Complete the Flickr request and marshal to the UI thread
using (HttpWebResponse response = (HttpWebResponse)((HttpWebRequest)ar.AsyncState).EndGetResponse(ar))
{
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
string results = reader.ReadToEnd();
}
}
}
The second piece I tried was:
private void WebClient_Click(object sender, RoutedEventArgs e)
{
Test t1 = new Test() { Name = "Civics", Marks = 100 };
DataContractJsonSerializer jsondata = new DataContractJsonSerializer(typeof(Test));
MemoryStream mem = new MemoryStream();
jsondata.WriteObject(mem, t1);
string josnserdata = Encoding.UTF8.GetString(mem.ToArray(), 0, (int)mem.Length);
WebClient cnt = new WebClient();
cnt.UploadStringCompleted += new UploadStringCompletedEventHandler(cnt_UploadStringCompleted);
cnt.Headers["Content-type"] = "application/json";
cnt.Encoding = Encoding.UTF8;
cnt.UploadStringAsync(new Uri("http://www.dipzo.com/game/services.php"), "POST", josnserdata);
}
void cnt_UploadStringCompleted(object sender, UploadStringCompletedEventArgs e)
{
var x = e;
}
The code on the server to consume the service is in PHP and is essentially:
var_dump($_POST)
This should output whatever is coming into the post array. I've tested it with a simple PHP client and it works. Just can't get it to work in silverlight. In silverlight I just keep getting an empty array.

You should change the Content-type to application/x-www-form-urlencoded and not application/json which is not a known type yet.

Not that I think anyone is still paying attention tot his old question, but I'm betting that the problem was that it actually WAS getting to the server, but that the server routed the result back to the SL application. This is the behavior I'm seeing with a similar situation from SL5 usingWebClient.UploadStringAsync.
I'm about to implement/test a technique I ran across yesterday which uses a dynamically built, "real" page post from SL; I'll report my findings shortly.
UPDATE -- THIS SOLUTION WORKS:
http://www.codeproject.com/Tips/392435/Using-HTTP-Form-POST-method-to-pass-parameters-fro
I've just tested it in my application (SL5 inside MVC) and it works just fine. Make sure you check the HttpContext.Request.Form["fieldname"] to get the value(s) that you want. I used this technique to submit JSON and was able to return a generated Word document for the user.
Once I implemented this I was able to get rid of the unnecessary WebClient that I was attempting to use before.

POST Json String to Remote PHP Script using Json.NET

I am encountering an unusually strange behavior when POSTing a Json string to a PHP webserver. I use the JsonTextWriter object to create the Json string. I then send the Json string as a POST request. Please see comments. The HTML response in the code is returning the correct output, but when viewed in a browser, the web page displays either NULL or array(0) { }.
private void HttpPost(string uri, string parameters)
{
WebRequest webRequest = WebRequest.Create(uri);
webRequest.ContentType = "application/x-www-form-urlencoded"; // <- Should this be "application/json" ?
webRequest.Method = "POST";
byte[] bytes = Encoding.UTF8.GetBytes(parameters);
string byteString = Encoding.UTF8.GetString(bytes);
Stream os = null;
try
{ // Send the Post Data
webRequest.ContentLength = bytes.Length;
os = webRequest.GetRequestStream();
os.Write(bytes, 0, bytes.Length);
Console.WriteLine(String.Format(#"{0}", byteString)); // <- This matches the Json object
}
catch (WebException ex)
{ //Handle Error }
try
{ // Get the response
WebResponse webResponse = webRequest.GetResponse();
if (webResponse == null) { return null; }
StreamReader sr = new StreamReader(webResponse.GetResponseStream());
Console.WriteLine(sr.ReadToEnd().Trim()); // <- Server returns string response (full HTML page)
}
catch (WebException ex)
{ //Handle Error }
}
Relevant PHP code on the server:
$json = json_encode($_POST); # Not 'standard way'
var_dump(json_decode($json));
Any suggestions would be greatly appreciated.
Thanks

Try using "application/json" as the content type. Also, check the request logs or maybe do a port 80 trace if you can to view what's being sent to the server in the request body.
You can also narrow the scope of the problem -- is it the C# code or the PHP code that's bad -- by writing a quick JQuery ajax function that sends some JSON to the PHP server. This isolation of the PHP code from the C# code will tell you if the PHP is at least working correctly. If it is, then the problem is in the C# code.