I am running a very simple Web application (Asp.Net MVC3) on Win 7 IIS.
I have a very simple HTTP GET API which returns hello world.
Calling:
http://localhost/helloworld
Returns:
Hello World!
This works perfectly over a browser.
But when I write an app which tries to pull this URL using a webclient, I get the following error:
{"Unable to read data from the transport connection: The connection was closed."}
My Code is as follows
WebClient web = new WebClient();
var response = web.DownloadString("http://localhost/helloworld");
My IIS Settings are as follows
What should I be looking at? I have been at this for hours and I have run out of options to try! Any help will be really appreciated!
Thanks.
I suspect it's because WebClient does not send some of the HTTP headers:
A WebClient instance does not send optional HTTP headers by default. If your request requires an optional header, you must add the header to the Headers collection. For example, to retain queries in the response, you must add a user-agent header. Also, servers may return 500 (Internal Server Error) if the user agent header is missing. http://msdn.microsoft.com/en-us/library/system.net.webclient(v=vs.80).aspx
Try using HttpWebRequest instead. http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.aspx
I finally figured out what the issue was and instead of it being an IIS specific issue - which I was leaning towards, it turned out to be an issue with the code that I wrote.
Adding details here incase someone else runs into a similar problem.
I had the following method in my code which I was using to send the response of the request as a JSON object.
private void sendJsonResult(string result) {
Response.StatusCode = 200;
Response.Headers.Add("Content-Type", "application/json; charset=utf-8");
Response.Flush();
Response.Write(result);
Response.End();
Response.Close(); // <-- This is the problem statement
}
On digging around a bit, I found out that we should not be doing a Response.Close().
A better explanation of this is here.
Once I removed that line, it started working perfectly - both in my consuming app as well as the web browser, etc.
If you will read the link above, you will clearly understand why we should not be using a Response.Close() - so I will not go into that description. Learnt a new thing today.
Related
I am sending http request to sandbox api which sometimes returns positive response but sometimes it returns bad request with same request data and headers. So I want to debug this request using fiddler during I run the .net core code hitting that api.
But I am not able to find any way to that. Can any one please help me out for the same. I have tried following code to do this:
var requestMessage = GenerateRequestMessage(HttpMethod.Put, uri, query);
requestMessage.Content = new ObjectContent<T>(value, new JsonMediaTypeFormatter(), (MediaTypeHeaderValue)null);
IWebProxy proxy = new WebProxy("127.0.0.1", 8888);
HttpClient.DefaultProxy = proxy;
return _httpClient.SendAsync(requestMessage);
but fiddler is not capturing this api request.
EDIT: I fixed the problem, see links in the answer.
I'm using the XMLHttpRequest AJAX API to send data from different websites to our server in PythonAnywhere.
Something odd happens: depending on the website, either we send successfully or we get this error
POST https://canecto.pythonanywhere.com/api/ 500 (Internal Server Error)
even though the same code is loaded.
I tried to manually open the request and send data via JavaScript console in Chrome but nothing changes.
Here is how the snippet looks like:
var url = "https://canecto.pythonanywhere.com/api/";
var xmlHttpPost = new XMLHttpRequest();
xmlHttpPost.open("POST", url, true);
xmlHttpPost.setRequestHeader("Content-type", "application/json");
var postData = {
page_url: window.location.href,
time_on_page: activeTime,
cookie: cookie,
/* some variables */
};
xmlHttpPost.onreadystatechange = function() {
if (xmlHttpPost.readyState == 4 && XMLHttpRequest.DONE) {
console.log('');
}
};
/* send data */
xmlHttpPost.send(JSON.stringify(postData));
I read here that the problem should not be the client-side JavaScript.
If I inspect on the server side, for the line requests.get(page_url, headers=HEADER, timeout=10)(where I try to access the page) I get this log:
I read on the Python request library that it may be something related to the SSL verification, but I have very little clue about it. I tried to check other similar questions but I have not found the answer.
Has anybody experienced anything similar and successfully solved it?
To whom it still uses Python < 2.7.9: this answer worked for me. SNI is not supported in Python 2, that means you should follow such answer and these requirements to make requests work with SSL certificate verification.
I'm not receiving the expected Response Content on the client when the resource returns BadRequest.
[HttpGet]
[Route("Test", Name = "Test")]
public async Task<IHttpActionResult> Test()
{
var result = BadRequest("test");
return result;
}
On client (see hurl.it example below) I simply receive the string Bad Request in the body:
The response on the server seems to be fine:
It was working fine at some point (returning strings or ModelState in content) and recently we noticed this problem. I can't think of any recent change on server that could cause it.
It works neither locally nor when deployed on server.
It can be reproduced in any ApiController in the project.
return Ok("test"); works as expected.
Does anyone know what can cause this behavior?
Thank you!
It is hard to tell what goes wrong.
Things you could check:
Perhaps is your error caused by invalid authentication request
Try with a new project, if that makes difference then you know it's your project and there are no errors caused by your local IIS and server settings (highly unlikely but you never know.
Check your App_Start folder, containing the BundleConfig, RouteConfig, FilterConfig,WebApiConfig`. Perhaps some custom settings did cause to give you bad request error while it might be a not found error.
Check if it's only on Get request or also on others, could be caused by different versions of assemblies.
Check if you only have the problem with 400, or does 401, 500 gives the same problem?
Check your Web.Config file, these might contain <CustomErrors> that might redirect, or throw there own errors.
After some comments, custom erros seemed to be the problem.
I'm trying to port my WP8 application to a Windows Store App and I'm getting an HttpRequestException when performing the getStringAsync of the HttpClient.
Here is the code snippet giving me the issue:
HttpClient client = new HttpClient();
Stream stream = await client.GetStreamAsync(new Uri("http://www.psnapi.com.ar/ps3/api/psn.asmx/getPSNID?sPSNID=philippemexes", UriKind.Absolute));
and here is the complete exception message:
HttpRequestException: Response status code does not indicate success: 500 (Internal Server Error).
I have to said that the indicated URL works in the browser and the exactly same code works properly in the Windows Phone project too.
Does anyone knows which could be a possible solution to get the desired xml to a string and why is this working for Windows Phone and not for a WinRT app?
Thank you very much
Stefano
Fiddler is your friend!
Appears that service isn't too happy about being called when there's not a user-agent string passed in the request headers. Try adding:
client.DefaultRequestHeaders.Add("user-agent", "blah blah blah");
between your two lines of code. There's nothing magic in the blah blah blah part :), and it seems to work with your service, but who knows what, if any, interpretation the service is making of the UA string.
I'm getting repeated Microsoft.Http.HttpStageProcessingException timeout exceptions while trying to use the REST Starter kit's HttpClient. This has been working fine when used locally, but is failing when going remote.
The client is a c# process that runs as a windows service and uses HttpClient for making REST calls to our Java app server running in Tomcat6. When I started troubleshooting this, I came across a similar post on MSDN's forums: http://social.msdn.microsoft.com/Forums/en/wcf/thread/88487549-ce45-49d3-95e4-7ed413cbcfbc
Unfortunately, I can't isolate it to simply a Content-Length problem.
If anyone has any suggestions on how to solve this problem, I would greatly appreciate it - even if it means using HttpWebRequest directly. I understand HttpClient uses HttpWebRequest under the hood, but perhaps it's making some assumptions.
Found the solution. It turns out that the default number of outbound http connections when using the HttpClient seems to be 2. After I used the ServicePointManager static singleton to set the DefaultConnectionLimit for my client AppDomain to 10, everything worked fine.
Now, this is a little concerning, however - because I'm used to writing multi-threaded apps and using the new .NET 4 Tasks - so I really don't like having hard limits on outbound connections. Can anyone provide any links that provide details on how the low-level .NET Http handling works and what knobs control what settings?
Thanks again for the help,
Bob
NEVERMIND - found it myself, should have googled first - this MSDN blog on the Http Client protocol provides a good description of what's going on under-the-hood:
httpclient protocol blog
If it works locally or remotely via Fiddler then it is a problem with HTTP proxy. Your current configuration is not using proxy but Fiddler by default uses proxy configured for IE.
Get the same problem and solution is to Dispose method on response (maybe method named Close may be more clear) else response still occupy the socket and you have to increase the DefaultConnectionLimit to open new socket for each new request untill max limit reach (dirty and slow).
So the solution was:
HttpResponseMessage resp = this.HttpClient.Delete(uri);//or verb get/post/put
try {
//.... do what you need with response
}
finally {
resp.Dispose(); //free the socket for a new request
}