Develop Reference

HttpWebRequest random 'request timed out' exception

I am currently developing in Unity (in particular using C#) and I'm stuck with HttpWebRequest - HttpWebResponse random timeouts.
I have some methods that send a POST request to a server I host on my local machine (XAMPP) to use various php scripts which are going to fetch informations from MySQL Database (hosted with XAMPP) and give back those info in JSON format.
Then I handle these JSON informations with my C# scripts.
The problem is that when I run the first test all is good:I can get the JSON data from my Server and show it in the Debug Console.
When I run the second test,a WebException is raised with error:
WebException - The request timed out
After that second test,if I run again and again,the problem keeps presenting in a random way.
I followed all the guidelines I found on the internet on how to setup a webrequest - webresponse properly,in particular I tried to use ServicePoint.DefaultConnectionLimit and ServicePoint.MaxServicePointIdleTime,without any result.
The general structure of my methods (regarding the web request/response part) is something like that:
public void WebMethod(){
string post_url = "http://localhost/service.php?someparam=1&someparam=2";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(post_url);
request.Method = "POST";
request.KeepAlive = false;
request.Timeout = 5000;
request.Proxy = null;
string Response = "";
try
{
using (HttpWebResponse resp = request.GetResponse() as HttpWebResponse)
{
using (Stream objStream = resp.GetResponseStream())
{
using (StreamReader objReader = new StreamReader(objStream, Encoding.UTF8))
{
Response = objReader.ReadToEnd();
objReader.Close();
}
objStream.Flush();
objStream.Close();
}
resp.Close();
}
}catch(WebException e)
{
Debug.Log(e.Message);
}
finally
{
request.Abort();
}
//tried this one after reading some related answers here on StackOverflow,without results
//GC.Collect();
Debug.Log("SERVER RESPONSE:" + Response);
//Response Handling
}
I know that it may be something related to a wrong abort on the HttpWebRequest / Response or maybe related to the HTTP 1.1 connections limit,but I can't figure out any solution at the moment.
Any help is appreciated.

HttpWebRequest .GetResponse throws WebException 'The operation has timed out'

I've been working on a project which makes use of an RTC API and forms authentication. I've hit a bit of bizarre behaviour and I just can't figure this one out.
The scenario that has played out to date is that I can successfully run this project locally end to end. That is, this specific piece of code can:
Contact the remote server and successfully authenticate
After authentication I'm able to pass XML to update a ticket in RTC
The problem starts when I publish to our IIS (7.5) server. All works fine right up until the last .GetResponse call which uses a PUT method to pass my XML to update the ticket in RTC. I keep getting 'The operation has timed out'.
I've spent literally days trying to figure this one out doing all manner of things but nothing has proved useful.
As a test I changed the PUT method on the second call to a GET. And it works! If I used a PUT with the .AllowAutoRedirect = false it works in that I get a response back, but then nothing happens on the RTC side so the request is clearly being ignored. I also noticed that the status being returned is marked as 'Found' instead of 'OK'.
Some people thought at this stage perhaps it was a lack of connectivity between the remote server and the web server. This wouldn't be the case as authentication works and this happens against the same server. I have also manually passed the XML / PUT call using the RESTClient on the web server which was accepted fine.
I just can't understand why it works end to end when running locally, but plays up once deployed to IIS?
I tried using log tracing and I'm not entirely sure if I'm getting anything useful from it. It might be totally unrelated but I can see this in the log that is generated on the IIS server:
<EventData>
<Data Name="ContextId">{00000000-0000-0000-12AF-0080000000F8}</Data>
<Data Name="ModuleName">ManagedPipelineHandler</Data>
<Data Name="Notification">128</Data>
<Data Name="HttpStatus">500</Data>
<Data Name="HttpReason">Internal Server Error</Data>
<Data Name="HttpSubStatus">0</Data>
<Data Name="ErrorCode">0</Data>
<Data Name="ConfigExceptionInfo"></Data>
</EventData>
As I say, I'm not sure if this is even related to the problem I'm having, but rather than ignore it I thought I'd share.
Code that forms the call (excuse the standard of coding, it's work in progress and got messy trying out different things to fix this problem)
//Setup webrequest
CookieContainer _cookies = new CookieContainer();
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(getPath);
var test44 = test4.ToString();
request.CookieContainer = _cookies;
request.ContentType = "application/rdf+xml";
request.Accept = "application/rdf+xml";
request.Method = "PUT";
request.AllowAutoRedirect = true;
request.AllowWriteStreamBuffering = true;
request.Timeout = 40000;
byte[] bytes = Encoding.ASCII.GetBytes(test44);
request.ContentLength = bytes.Length;
Stream dataStream = request.GetRequestStream();
dataStream.Write(bytes, 0, bytes.Length);
dataStream.Close();
//Pass request
logger.Info("Made it up to start of RTC request for secure document.");
using (HttpWebResponse getrespn = requestSecureDocument(request, "https://myserver:9100/jazz", "username", "pass", test44))
{
//Stream ReceiveStream = getrespn.GetResponseStream();
// Encoding encode = System.Text.Encoding.GetEncoding("utf-8");
//StreamReader readStream = new StreamReader(ReceiveStream);
//response = readStream.ReadToEnd();
getrespn.Close();
}
The segment of code which interacts with the RTC server (based on the example from: https://nkumar83.wordpress.com/2013/06/13/consuming-rtc-rational-team-concert-oslc-apis-using-c-post-1-authentication/ with my own tweaks):
public static HttpWebResponse requestSecureDocument(HttpWebRequest _requestItem, string _rtcServerURL, string _userName, string _password, string passXml)
{
try
{
//FormBasedAuth Step 1: Request the resource
HttpWebRequest _request = (HttpWebRequest)WebRequest.Create(_requestItem.RequestUri);
_request.CookieContainer = _requestItem.CookieContainer;
//store the response in _docResponse variable
HttpWebResponse _docResponse = (HttpWebResponse)_request.GetResponse();
//HttpStatusCode.OK indicates that the request succeeded
if (_docResponse.StatusCode == HttpStatusCode.OK)
{
//X-com-ibm-team... header signifies form based authentication is being used
string _rtcAuthHeader = _docResponse.Headers["X-com-ibm-team-repository-web-auth-msg"];
if ((_rtcAuthHeader != null) && _rtcAuthHeader.Equals("authrequired"))
{
_docResponse.GetResponseStream().Flush();
_docResponse.Close();
//Prepare form for authentication
HttpWebRequest _formPost = (HttpWebRequest)WebRequest.Create(_rtcServerURL + "/j_security_check");
_formPost.Method = "POST";
_formPost.Timeout = 30000;
_formPost.CookieContainer = _request.CookieContainer;
_formPost.Accept = "text/xml";
_formPost.ContentType = "application/x-www-form-urlencoded";
string _authString = "j_username=" + _userName + "&j_password=" + _password;
Byte[] _outBuffer = Encoding.UTF8.GetBytes(_authString);
_formPost.ContentLength = _outBuffer.Length;
Stream _str = _formPost.GetRequestStream();
_str.Write(_outBuffer, 0, _outBuffer.Length);
_str.Close();
//FormBasedAuth Step 2: Submit the login form and get response
HttpWebResponse _formResponse = (HttpWebResponse)_formPost.GetResponse();
_rtcAuthHeader = _formResponse.Headers["X-com.ibm-team.repository-web-auth-msg"];
//Check if auth failed
if ((_rtcAuthHeader != null) && _rtcAuthHeader.Equals("authfailed"))
{
//auth fialed
var fail = "";
}
else
{
//login successful
//FormBasedAuth Step 3: Resend the request for the protected resource
_formResponse.GetResponseStream().Flush();
_formResponse.Close();
using (HttpWebResponse getresp = (HttpWebResponse)_requestItem.GetResponse()) *** THIS IS TH LINE WHICH THROWS THE EXCEPTION ***
{
return getresp;
}
}
}
}
return _docResponse;
}
catch (WebException e)
{
var filePath = AppDomain.CurrentDomain.GetData("DataDirectory") + #"/trapA.xml";
using (StreamWriter writer = new StreamWriter(filePath, true))
{
writer.WriteLine("Message: Failed to trigger getresponse successfully: " + e);
}
}
return null;
}
Hope someone out there can help :o)

Well I'm pleased to say I've finally got to the bottom of this one. Turns out the problem wasn't anything to do with IIS and does actually work when published 'if' I'm not using the RTC client to make updates to a ticket.
The short story is that our RTC client uses a custom script to post out to our web api. However the RTC client appears to put a record lock on the ticket your trying to update which is persisted until a response from our API is provided. Of course this can't happen because part of the response is to confirm if the update was successful which can't happen due to the lock made by the RTC client.
The solution was to get the call in from RTC closed as quickly as possible. So the segment of code which authenticates and calls back out to RTC to make updates is now wrapped around with some new code to create a new thread. This has allowed the connection to be closed in about 5 seconds, all the while our app continues to make the necessary calls to complete the transaction.
Thread t = new Thread(() = > {
//code here
}

Received "Request was cancelled" error when writing JSON data to HttpWebRequest

I've a iOS application written in C# using Monodevelop, and as part of the application I make a call to a web service. The web service call requires that JSON data to be written to the request. However, I receive an error the first time I attempt to write the data; all subsequent calls to the same method with the same parameters work. The following is a snippet of the relavent code:
// Start snippet
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create (_connectionSettings.Uri);
request.Timeout = 15000; // milliseconds
if (_connectionSettings.Username != "") {
request.Credentials = new NetworkCredential (_connectionSettings.Username, _connectionSettings.Password);
}
if (post) {
request.Method = "POST";
request.ContentType = "application/json";
if (jsonData != null) {
byte[] byteArray = System.Text.Encoding.UTF8.GetBytes(jsonData);
request.ContentLength = byteArray.Length;
using (Stream ds = request.GetRequestStream()) { //<--- ERROR HERE
ds.Write (byteArray, 0, byteArray.Length);
}
} else {
request.Method = "GET";
}
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse()) {
// end snippet
The error I get is as follows:
System.Net.WebException: Request was cancelled. --->
System.Exception:
Cannot close the stream until all bytes are written
--- End of inner exception stack trace --- at
System.Net.WebConnectionStream.Close ()
[0x00121] in
/Developer/MonoTouch/Source/mono/mcs/class/System/System.Net/WebConnectionStream.cs:785
at System.IO.Stream.Dispose () [0x00000] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.IO/Stream.cs:93
at
MyCustomMethod (System.String& responseString, System.String jsonData, Boolean post,
Boolean suppressAlert) [0x00101] in /Path/To/My/Class.cs:192
Any ideas what I could be doing wrong?
EDIT
Ok, apparently when stepping through the application, the method works every time. What I've noticed is that when the error is throw, the request.ContentLength is zero despite the fact that the byteArray.Length is non-zero. However when stepping through the application, the request.ContentLength keeps the expected value of the byteArray.Length.

Ok, it looks like we don't need to set the request.ContentLength at all. Removing the line:
request.ContentLength = byteArray.Length;
fixes the issue entirely. I'm still curious if this is a bug in the library as most of the code samples show setting the HttpWebRequest's ContentLength, and it works properly on subsequent tries.

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.)

C# HTTP web request keeps timing out

I am making a Http Webrequest to an available site that I can visit fine, but the HTTP Web request keeps timing out. Is there any reason why this code might allow it to timeout when it shouldn't?
I've tried upping the timeout setting, but it still continues to timeout.
Uri CameraUrl = new Uri("http://" + cfg_cameraIps[i]);
HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(CameraUrl);
myRequest.Timeout = 5000;
myRequest.Method = "HEAD";
try
{
HttpWebResponse webresponse;
webresponse = (HttpWebResponse)myRequest.GetResponse();
if (webresponse.StatusCode.ToString() == "OK")
{
continue;
}

You're not closing your web response - if you find that the first couple of requests work, but ones after that don't, then that's the problem. It's trying to reuse the existing connection to the server, but it can't because you haven't closed the response.
Change your code to:
using (HttpWebResponse webresponse = (HttpWebResponse) myRequest.GetResponse())
{
if (webresponse.StatusCode == HttpStatusCode.OK)
{
continue;
}
...
}
and see if that helps.
If it's failing on the very first request to the server, then that's something different. In that case, use Wireshark to see what's going on at the network level.
Note that in the code above I've also removed the string conversion in favour of comparing the status codes directly.