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 methods throws 404 exception

I want to download one image from url using console application.
I have used following code:
string sourceUrl = "http://i.ytimg.com/vi/pvBnYBsUi9A/default.jpg"; // Not Found
//string sourceUrl = "http://i.ytimg.com/vi/OrxZAN1FZUY/default.jpg"; // Found
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(sourceUrl);
HttpWebResponse response = null;
try
{
response = (HttpWebResponse)request.GetResponse();
}
catch (Exception)
{
}
Above code throws exception in line "response = (HttpWebResponse)request.GetResponse();"
but when I am accessing "http://i.ytimg.com/vi/pvBnYBsUi9A/default.jpg" url in my browser then image will be display.
What I am missing here?

I tried that url "http://i.ytimg.com/vi/pvBnYBsUi9A/default.jpg" in Chrome
developer tools. It also receives a 404, but the response includes the image, which displays.
Your code is not the cause of the exception. The site is returning a 404 and your code gets an exception.
You could write logic to look at the response even if you get a 404 and decide whether to take it anyway, as the browser does.
It looks like you can get the response returned by the site if you catch WebException, which allows you to see the http request status and the response, per the documentation.
Example from the .Net 4.5 doc...
try
{
// Creates an HttpWebRequest for the specified URL.
HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(url);
// Sends the HttpWebRequest and waits for a response.
HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse();
if (myHttpWebResponse.StatusCode == HttpStatusCode.OK)
Console.WriteLine("\r\nResponse Status Code is OK and StatusDescription is: {0}",
myHttpWebResponse.StatusDescription);
// Releases the resources of the response.
myHttpWebResponse.Close();
}
catch(WebException e)
{
Console.WriteLine("\r\nWebException Raised. The following error occured : {0}",e.Status);
}
catch(Exception e)
{
Console.WriteLine("\nThe following Exception was raised : {0}",e.Message);
WebException has Response and Status properties. So it looks like the .Net way to deal with this is to catch WebException and determine how to handle based on the status and response content (if necessary).

Posting to a REST webservice from .NET?

I was trying to hit a web service using the instructions here:
http://help.seeclickfix.com/kb/api/creating-an-issue
I came up with the code below:
string paramContent = "api_key=afs684eas3ef86saef78s68aef68sae&issue[summary]=abeTest&issue[lat]=39.26252982783172&issue[lng]=-121.01738691329956&issue[address]=111 Abe St., Nevada City, CA";
byte[] paramBytes = Encoding.UTF8.GetBytes(paramContent);
HttpWebRequest req = (HttpWebRequest)WebRequest.Create("http://seeclickfix.com/api/issues.xml");
req.Method = "POST";
req.ContentLength = paramBytes.Length;
//req.ContentType = "application/x-www-form-urlencoded";
using (Stream reqStream = req.GetRequestStream())
{
reqStream.Write(paramBytes, 0, paramBytes.Length);
}
using (HttpWebResponse resp = (HttpWebResponse)req.GetResponse()) //HERE!
{
if (resp.StatusCode != HttpStatusCode.OK)
{
string message = String.Format("POST failed. Received HTTP {0}", resp.StatusCode);
throw new ApplicationException(message);
}
StreamReader sr = new StreamReader(resp.GetResponseStream());
string response = sr.ReadToEnd();
Console.WriteLine(response + System.Environment.NewLine);
}
But at the line with the HERE! comment it throws the error:
The remote server returned an error: (500) Internal Server Error.
Can anyone see any problems with the way I am trying to implement this?

The 500 error you are getting indicates a problem on the server, not necessarily a problem with your code. You are successfully sending a request and receiving a response.
The problem could be a bug in the server, or a problem with the content of your request that the server can't handle. (Either way the server is failing to provide a valid error message like their documentation suggests it would)
You should start by making sure the content of your request is valid. See the example on the seeclickfix url you posted. Try directly posting with curl like they show, but use the content of your own message like so:
curl -v -d 'api_key=afs684eas3ef86saef78s68aef68sae&issue[summary]=abeTest&issue[lat]=39.26252982783172&issue[lng]=-121.01738691329956&issue[address]=111 Abe St., Nevada City, CA' http://seeclickfix.com/api/issues.xml
I expect you'll still get a 500 error (I just tried it and I got a 500 error).
Bottom line, it looks like their api is broken, not your logic.

You didn't do anything wrong. I tried making the request using Fiddler and it returned the same 500 status code.
If there was something wrong with the data you passed then they should have returned a 4XX response code.

C# Check url exist?

How can I check whether a page exists at a given URL?
I have this code:
private void check(string path)
{
try
{
Uri uri = new Uri(path);
WebRequest request = WebRequest.Create(uri);
request.Timeout = 3000;
WebResponse response;
response = request.GetResponse();
}
catch(Exception loi) { MessageBox.Show(loi.Message); }
}
But that gives an error message about the proxy. :(

First, you need to understand that your question is at least twofold,
you must first check if the server is responsive, using ping for example - that's the first check, while doing this, consider timeout, for which timeout you will consider a page as not existing?
second, try retrieving the page using many methods which are available on google, again, you need to consider the timeout, if the server taking long to replay, the page might still "be there" but the server is just under tons of pressure.

If the proxy needs to authenticate you with your Windows credentials (e.g. you are in a corporate network) use:
WebRequest request=WebRequest.Create(url);
request.UseDefaultCredentials=true;
request.Proxy.Credentials=request.Credentials;

try
{
Uri uri = new Uri(path);
HttpWebRequest request = HttpWebRequest.Create(uri);
request.Timeout = 3000;
HttpWebResponse response;
response = request.GetResponse();
if (response.StatusCode.Equals(200))
{
// great - something is there
}
}
catch (Exception loi)
{
MessageBox.Show(loi.Message);
}
You can check the content-type and length, see MSDN HTTPWebResponse.

At a guess, without knowing the specific error message or path, you could try casting the WebRequest to a HttpWebRequest and then setting the WebProxy.
See MSDN: HttpWebRequest - Proxy Property

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.