I experienced some strange issue while reading stream from HttpWebResponse. In case of successful response (200 status code) I get exception when access to Length property of stream. But in case of WebException when server returns some error (e.g. BadRequest) everything is perfect, Length works ok. I can get ContentLength directly from HttpWebResponse but want to know the reason of such behavior.
Here is debug screenshot of both cases
try
{
var request = (HttpWebRequest) WebRequest.Create(uriString);
request.Method = HttpMethod.Get.Method;
request.ContentType = "application/json";
response = (HttpWebResponse) request.GetResponse();
statusCode = response.StatusCode;
responseString = DecodeResponse(response);
}
catch (WebException ex)
{
response = (HttpWebResponse) ex.Response;
responseString = DecodeResponse(response);
statusCode = response.StatusCode;
}
private static string DecodeResponse(HttpWebResponse response)
{
byte[] data;
using (Stream stream = response.GetResponseStream())
{
data = new byte[stream.Length];
stream.Read(data, 0, data.Length);
}
return Encoding.UTF8.GetString(data);
}
The stream (ConnectStream) which is being created internally as part of the response does not support the Length property. Different streams support different properties depending on their implementation.
You could use a different way to read from the stream as in this post:
C# How do i convert System.Net.ConnectStream to a byte[] (array)
Related
I have this hardware from Patlite,
This hardware has an HTTP command control function, for example, if I copy the url "http://192.168.10.1/api/control?alert=101002" to chrome in my computer, it will activate the hardware as needed.
I want to send the command from my code.
I tried this code with no luck:
System.Net.ServicePointManager.Expect100Continue = false;
WebRequest request = WebRequest.Create("http://10.0.22.222/api/control");
request.Method = "post";
request.ContentType = "application/x-www-form-urlencoded";
string postData = "alert=101002";
byte[] byteArray = Encoding.UTF8.GetBytes(postData);
request.ContentLength = byteArray.Length;
// Get the request stream.
Stream dataStream = request.GetRequestStream();
// Write the data to the request stream.
dataStream.Write(byteArray, 0, byteArray.Length);
// Close the Stream object.
dataStream.Close();
WebResponse response = request.GetResponse();
There is a picture from the manual:
Thanks
You need to create a webrequest instance for this.
WebRequest request = WebRequest.Create("http://192.168.10.1/api/control?alert=101002");
WebResponse response = request.GetResponse();
You may need to set some properties as request method and credentials for this to work.
See this:
https://msdn.microsoft.com/en-us/library/456dfw4f(v=vs.100).aspx
public static string Get(string url, Encoding encoding)
{
try
{
var wc = new WebClient { Encoding = encoding };
var readStream = wc.OpenRead(url);
using (var sr = new StreamReader(readStream, encoding))
{
var result = sr.ReadToEnd();
return result;
}
}
catch (Exception e)
{
//throw e;
return e.Message;
}
}
like this code use the url "http://192.168.10.1/api/control?alert=101002" to send get request.Good luck!
I have read other similar questions and tried the solutions from those questions, but since that did not work, hence I am posting this here.
When I send POST request below, it fails with the following error message:
System.Net.ProtocolViolationException: You must write ContentLength bytes to the request stream before calling [Begin]GetResponse.
at System.Net.HttpWebRequest.GetResponse()
....
....
My GET requests for other URL end points are working fine, I am only having this issue while issuing a POST request. Also, I have already set the ContentLength in the code appropriately. I am still unable to send the POST request. Thoughts?
public void TestSubmitJobWithParams1()
{
const string RestActionPath = "URL_GOES_HERE";
// if you have multipe parameters seperate them with teh '&' delimeter.
var postData = HttpUtility.UrlEncode("MaxNumberOfRowsPerSFSTask") + "=" + HttpUtility.UrlEncode("3000");
var request = (HttpWebRequest)WebRequest.Create(RestActionPath);
request.Method = "POST";
request.Credentials = CredentialCache.DefaultCredentials;
request.PreAuthenticate = true;
request.ContentLength = 0;
request.Timeout = 150000;
request.CachePolicy = new RequestCachePolicy(RequestCacheLevel.BypassCache);
request.ContentType = "application/x-www-form-urlencoded";
byte[] bytes = Encoding.ASCII.GetBytes(postData);
request.ContentLength = bytes.Length;
Stream newStream = request.GetRequestStream();
newStream.Write(bytes, 0, bytes.Length);
string output = string.Empty;
try
{
using (var response = request.GetResponse())
{
using (var stream = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding(1252)))
{
output = stream.ReadToEnd();
}
}
}
catch (WebException ex)
{
if (ex.Status == WebExceptionStatus.ProtocolError)
{
using (var stream = new StreamReader(ex.Response.GetResponseStream()))
{
output = stream.ReadToEnd();
}
}
else if (ex.Status == WebExceptionStatus.Timeout)
{
output = "Request timeout is expired.";
}
}
catch (ProtocolViolationException e)
{
Console.WriteLine(e);
}
Console.WriteLine(output);
Console.ReadLine();
}
A few things:
Firstly, you don't need to set ContentLength directly - just leave it out (defaults to -1). You're actually calling it twice, so remove both calls.
Also, you need to call Close() on the stream before calling GetResponse()
Stream newStream = request.GetRequestStream();
newStream.Write(bytes, 0, bytes.Length);
newStream.Close();
Alternatively, you could have it within a using statement, which handles the closing and disposal for you):
using (var newStream = request.GetRequestStream())
{
newStream.Write(bytes, 0, bytes.Length);
}
You also don't technically need to use HttpUtility.UrlEncode() for the postData since there's nothing in your string that would violate a Url's integrity. Just do:
string postData = "MaxNumberOfRowsPerSFSTask=3000");
Let me know if that solves it for you.
For a more thorough rundown, check this out: http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.getresponse.aspx
Specifically, the section about ProtocolViolationException and also where it says:
When using the POST method, you must get the request stream, write the data to be posted, and close the stream. This method blocks waiting for content to post; if there is no time-out set and you do not provide content, the calling thread blocks indefinitely.
So I have a function like so:
private String SendRequest(String jsonRequest)
{
WebRequest webRequest = WebRequest.Create(_url);
byte[] paramBytes = Encoding.UTF8.GetBytes(jsonRequest);
byte[] responseBytes;
webRequest.Method = "POST";
webRequest.ContentType = "application/json";
webRequest.ContentLength = paramBytes.Length;
webRequest.Headers.Add("X-Transmission-Session-Id", _sessionId);
using (Stream oStream = webRequest.GetRequestStream())
{
oStream.Write(paramBytes, 0, paramBytes.Length);
}
WebResponse webResponse = webRequest.GetResponse();
using (Stream iStream = webResponse.GetResponseStream())
{
responseBytes = new byte[webResponse.ContentLength];
iStream.Read(responseBytes, 0, (int) webResponse.ContentLength);
}
return Encoding.UTF8.GetString(responseBytes);
}
The problem is, at the iStream.Read() stage, some of the bytes are lost. Using wireshark reveals all the bytes are sent to this machine, however .Net is loosing them somewhere along the way. In my current debugging session, for example, where webResponse.ContentLength = 4746 byte[3949] to byte[4745] are all 0's, but they should be populated. As a result, the UTF8 JSON string cuts off early and I can't deserialise my JSON.
I thought the code was pretty clear cut, I can't see where it's going wrong to loose those bytes.
Thanks for any help!
When reading from the stream you can get less bytes than requested.
http://msdn.microsoft.com/en-us/library/system.io.stream.read.aspx
The total number of bytes read into the buffer. This can be less than
the number of bytes requested if that many bytes are not currently
available, or zero (0) if the end of the stream has been reached.
msdn example for WebResponse.GetResponseStream():
http://msdn.microsoft.com/en-us/library/system.net.webresponse.getresponsestream.aspx
I fixed it by using StreamReader instead :)
private String SendRequest(String jsonRequest)
{
WebRequest webRequest = WebRequest.Create(_url);
byte[] paramBytes = Encoding.UTF8.GetBytes(jsonRequest);
String jsonResponse;
webRequest.Method = "POST";
webRequest.ContentType = "application/json";
webRequest.ContentLength = paramBytes.Length;
webRequest.Headers.Add("X-Transmission-Session-Id", _sessionId);
using (Stream oStream = webRequest.GetRequestStream())
{
oStream.Write(paramBytes, 0, paramBytes.Length);
oStream.Close();
}
WebResponse webResponse = webRequest.GetResponse();
using (Stream iStream = webResponse.GetResponseStream())
{
StreamReader reader = new StreamReader(iStream, Encoding.UTF8);
jsonResponse = reader.ReadToEnd();
reader.Close();
iStream.Close();
}
return jsonResponse;
}
I'm trying to solve an issue that I Mostly (70%) have (30% is succesfull).
I trying to do a webrequest (POST) with the following code:
private string HttpWebRequest(string busStopCode)
{
//XML input
string xml = "<?xml version='1.0' encoding='UTF-8' standalone='yes'?><Siri version='1.0' xmlns='http://www.siri.org.uk/'><ServiceRequest> <RequestTimestamp>2011-10-24T15:09:12Z</RequestTimestamp><RequestorRef><username></RequestorRef><StopMonitoringRequest version='1.0'> <RequestTimestamp>2011-10-24T15:09:12Z</RequestTimestamp><MessageIdentifier>12345</MessageIdentifier><MonitoringRef>"+busStopCode+"</MonitoringRef></StopMonitoringRequest></ServiceRequest></Siri>";
string responseFromServer = null;
// Create a request using a URL that can receive a post.
WebRequest request = WebRequest.Create("http://<username>:<username>#nextbus.mxdata.co.uk/nextbuses/1.0/1");
// Set the Method property of the request to POST.
request.Method = "POST";
request.Credentials = CredentialCache.DefaultNetworkCredentials;
// Create POST data and convert it to a byte array.
string postData = xml;
byte[] byteArray = Encoding.UTF8.GetBytes(postData);
// Set the ContentType property of the WebRequest.
request.ContentType = "application/x-www-form-urlencoded";
// Set the ContentLength property of the WebRequest.
request.ContentLength = byteArray.Length;
// Get the request stream.
Stream dataStream = request.GetRequestStream();
// Write the data to the request stream.
dataStream.Write(byteArray, 0, byteArray.Length);
// Close the Stream object.
dataStream.Close();
// Get the response.
WebResponse response = null;
while (response == null)
{
try
{
response = request.GetResponse();
}
catch (Exception e)
{
MessageBox.Show(e.ToString());
}
}
// Display the status.
MessageBox.Show(((HttpWebResponse)response).StatusDescription + " Completed");
// Get the stream containing content returned by the server.
dataStream = response.GetResponseStream();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader(dataStream);
// Read the content.
responseFromServer = reader.ReadToEnd();
// Clean up the streams.
reader.Close();
dataStream.Close();
response.Close();
return responseFromServer;
}
When I call this function I get mostly a messagebox of my exception with:
"System.Net.WebException: The remote Server returned an error(401) not authorized with System.Net.Http.Webrequest.GetResponse() with WindowsFormApplication1.Form1.HttpWebRequest(string BusstopCode) in <my pathfile>...."
What I'm doing wrong?
I already tried several solutions from previous threads but without success...
Thanks!
how can i upload a large string (in my case XML with BLOB) with POST without getting Timeout with GetResponse?
Changing the timeout helps, but this isn't really a solution.
If the Server is really death or the POST was interrupted i have to wait for the extrem large timeout.
Any Idea?
HttpWebRequest webRequest = null;
string response = "";
byte[] bytes = Encoding.UTF8.GetBytes(xml);
try
{
webRequest = (HttpWebRequest)WebRequest.Create("http://" + this.host + ":" + this.port);
webRequest.ContentType = "application/x-www-form-urlencoded";
webRequest.Method = "POST";
webRequest.Timeout = 5000;
webRequest.ContentLength = bytes.Length;
using (Stream requeststream = webRequest.GetRequestStream())
{
requeststream.Write(bytes, 0, bytes.Length);
requeststream.Close();
}
using (HttpWebResponse webResponse = (HttpWebResponse)webRequest.GetResponse())
{
using (StreamReader sr = new StreamReader(webResponse.GetResponseStream()))
{
response = sr.ReadToEnd().Trim();
sr.Close();
}
webResponse.Close();
}
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
return response;
Yes, this is pretty much expected http behaviour.
Options:
have a large timeout (you've already done this), and accept that it could take a long time to legitimately time out (as opposed to taking a while because of bandwidth)
maybe you can apply gzip on the request (and tell the server you're sending it compressed); I honestly don't know if this is supported automatically, but it could certainly be done by the api explicitly checking for a particular header and applying gzip decompression on the payload
change the api to perform a number of small uploads, and a completion message
live with it