I am working on an ASP.NET framework 2.0 application. On a particular page I am providing a link to user. By clicking on this link a window opens with another aspx page. This page actually sends http request to a third-party url which points to a file(like - mirror urls to download file from cloud). The http response is sent back to user on the very first page using response.write from where user click the link.
Now, the problem I am facing is if the file size is low then it works fine. But, if the file is large (i.e., more than 1 GB), then my application waits until whole file is downloaded from the URL. I have tried using response.flush() to send chunk by chunk data to user, but still user is unable to use application because the worker process is busy getting streams of data from third party URL.
Is there any way by which large files can be downloaded asynchronously so that my pop-up window finishes its execution(download will be in progress) and also user can do other activities on application parallely.
Thanks,
Suvodeep
Use WebClient to read the remote file. Instead of downloading you can take the Stream from the WebClient. Put that in while() loop and push the bytes from the WebClient stream in the Response stream. On this way, you will be async downloading and uploading at the same time.
HttpRequest example:
private void WriteFileInDownloadDirectly()
{
//Create a stream for the file
Stream stream = null;
//This controls how many bytes to read at a time and send to the client
int bytesToRead = 10000;
// Buffer to read bytes in chunk size specified above
byte[] buffer = new byte[bytesToRead];
// The number of bytes read
try
{
//Create a WebRequest to get the file
HttpWebRequest fileReq = (HttpWebRequest)HttpWebRequest.Create("Remote File URL");
//Create a response for this request
HttpWebResponse fileResp = (HttpWebResponse)fileReq.GetResponse();
if (fileReq.ContentLength > 0)
fileResp.ContentLength = fileReq.ContentLength;
//Get the Stream returned from the response
stream = fileResp.GetResponseStream();
// prepare the response to the client. resp is the client Response
var resp = HttpContext.Current.Response;
//Indicate the type of data being sent
resp.ContentType = "application/octet-stream";
//Name the file
resp.AddHeader("Content-Disposition", $"attachment; filename=\"{ Path.GetFileName("Local File Path - can be fake") }\"");
resp.AddHeader("Content-Length", fileResp.ContentLength.ToString());
int length;
do
{
// Verify that the client is connected.
if (resp.IsClientConnected)
{
// Read data into the buffer.
length = stream.Read(buffer, 0, bytesToRead);
// and write it out to the response's output stream
resp.OutputStream.Write(buffer, 0, length);
// Flush the data
resp.Flush();
//Clear the buffer
buffer = new byte[bytesToRead];
}
else
{
// cancel the download if client has disconnected
length = -1;
}
} while (length > 0); //Repeat until no data is read
}
finally
{
if (stream != null)
{
//Close the input stream
stream.Close();
}
}
}
WebClient Stream reading:
using (WebClient client = new WebClient())
{
Stream largeFileStream = client.OpenRead("My Address");
}
Related
I'm trying to play in Chrome Browser video with source from Web Api
<video id="TestVideo" class="dtm-video-element" controls="">
<source src="https://localhost:44305/Api/FilesController/Stream/Get" id="TestSource" type="video/mp4" />
</video>
In order to implement progressive downloading I'm using PushStreamContent in server response
httpResponce.Content = new PushStreamContent((Action<Stream, HttpContent, TransportContext>)new StreamService(fileName,httpResponce).WriteContentToStream);
public async void WriteContentToStream(Stream outputStream, HttpContent content, TransportContext transportContext)
{
//here set the size of buffer
int bufferSize = 1024;
byte[] buffer = new byte[bufferSize];
//here we re using stream to read file from db server
using (var fileStream = IOC.Container.Resolve<IMongoCommonService>().GridRecordFiles.GetFileAsStream(_fileName))
{
int totalSize = (int)fileStream.Length;
/*here we are saying read bytes from file as long as total size of file
is greater then 0*/
_response.Content.Headers.Add("Content-Length", fileStream.Length.ToString());
// _response.Content.Headers.Add("Content-Range", "bytes 0-"+ totalSize.ToString()+"/"+ fileStream.Length);
while (totalSize > 0)
{
int count = totalSize > bufferSize ? bufferSize : totalSize;
//here we are reading the buffer from orginal file
int sizeOfReadedBuffer = fileStream.Read(buffer, 0, count);
//here we are writing the readed buffer to output//
await outputStream.WriteAsync(buffer, 0, sizeOfReadedBuffer);
//and finally after writing to output stream decrementing it to total size of file.
totalSize -= sizeOfReadedBuffer;
}
}
}
After I load page video start to play immediately, but I can not seek for previous (already played) seconds of video or rewind it as well in Google Chrome browser. When I try to do this, video goes back to the beggining.
But in Firefox and Edge it's working like it should be, I can go back to already played part. I don't know how to solve this issue in Google Chrome Browser
You should use HTTP partial content. As it described here:
As it turns out, looping (or any sort of seeking, for that matter) in elements on Chrome only works if the video file was served up by a server that understands partial content requests.
So there are some articles that may help you to implement it. Try these links:
HTTP 206 Partial Content In ASP.NET Web API - Video File Streaming
How to work with HTTP Range Headers in WebAPI
Here is an implementation of responding to Range requests correctly - it reads a video from a file and returns it to the browser as a stream, so it doesnt eat up your server's ram. You get the chance to decide the security you want to apply etc in code.
[HttpGet]
public HttpResponseMessage Video(string id)
{
bool rangeMode = false;
int startByte = 0;
if (Request.Headers.Range != null)
if (Request.Headers.Range.Ranges.Any())
{
rangeMode = true;
var range = Request.Headers.Range.Ranges.First();
startByte = Convert.ToInt32(range.From ?? 0);
}
var stream = new FileStream(/* FILE NAME - convert id to file somehow */, FileMode.Open, FileAccess.Read, FileShare.ReadWrite) {Position = startByte};
if (rangeMode)
{
HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.PartialContent)
{
Content = new ByteRangeStreamContent(stream, Request.Headers.Range, MediaTypeHeaderValue.Parse(fileDetails.MimeType))
};
response.Headers.AcceptRanges.Add("bytes");
return response;
}
else
{
HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK)
{
Content = new StreamContent(stream)
};
response.Content.Headers.ContentType = MediaTypeHeaderValue.Parse(fileDetails.MimeType);
return response;
}
}
I am experiencing some strange behaviour from my code which i am using to stream files to my clients.
I have a mssql server which acts as a filestore, with files that is accessed via an UNC path.
On my webserver i have some .net code running that handles streaming the files (in this case pictures and thumbnails) to my clients.
My code works, but i am experiencing a constant delay of ~12 sec on the initial file request. When i have made the initial request it is as the server wakes up and suddenly becomes responsive only to fall back to the same behaviour some time after.
At first i thought it was my code, but from what i can see on the server activity log there is no ressource intensive code going on. My theory is that at each call to the server the path must first be mounted and that is what causes the delay. It will then unmount some time after and will have to remount.
For reference i am posting my code (maybe i just cannot see the problem):
public async static Task StreamFileAsync(HttpContext context, FileInfo fileInfo)
{
//This controls how many bytes to read at a time and send to the client
int bytesToRead = 512 * 1024; // 512KB
// Buffer to read bytes in chunk size specified above
byte[] buffer = new Byte[bytesToRead];
// Clear the current response content/headers
context.Response.Clear();
context.Response.ClearHeaders();
//Indicate the type of data being sent
context.Response.ContentType = FileTools.GetMimeType(fileInfo.Extension);
//Name the file
context.Response.AddHeader("Content-Disposition", "filename=\"" + fileInfo.Name + "\"");
context.Response.AddHeader("Content-Length", fileInfo.Length.ToString());
// Open the file
using (var stream = fileInfo.OpenRead())
{
// The number of bytes read
int length;
do
{
// Verify that the client is connected
if (context.Response.IsClientConnected)
{
// Read data into the buffer
length = await stream.ReadAsync(buffer, 0, bytesToRead);
// and write it out to the response's output stream
await context.Response.OutputStream.WriteAsync(buffer, 0, length);
try
{
// Flush the data
context.Response.Flush();
}
catch (HttpException)
{
// Cancel the download if a HttpException happens
// (ie. the client has disconnected by we tried to send some data)
length = -1;
}
//Clear the buffer
buffer = new Byte[bytesToRead];
}
else
{
// Cancel the download if client has disconnected
length = -1;
}
} while (length > 0); //Repeat until no data is read
}
// Tell the response not to send any more content to the client
context.Response.SuppressContent = true;
// Tell the application to skip to the EndRequest event in the HTTP pipeline
context.ApplicationInstance.CompleteRequest();
}
If anyone could shed some light over this problem i would be very grateful!
I am downloading file using System.Net.ConnectStream. However to support pause functionality for downloading,what I am doing is create new connection on click of start as follows:
this.InputStream = CreateLink(this.URL);
In CreateLink I check whether file is updated at server and return the corresponding stream for downloading.
I download file as chunk of bytes as:
InputStream.Read(buffer, offset, bytesToRead);
The Problem is it starts reading from beginning and not where it is paused.Also I am unable to use this.InputStream.Position = CurrentPosition; to set position of InputStream since it is nonseekable.Moreover,Stream supports 'Accept-Ranges' as 'bytes'
So, How can I begin downloading from paused position?
Update:
'this' refers to the instance of downloader as:
Downloader downloader = new Downloader();
HttpWebRequest request = (HttpWebRequest)GetRequest(path);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
downloader.InputStream = response.GetResponseStream();
I am referring to this article to understand file downloads using C#.
Code uses traditional method to read Stream like
((bytesSize = strResponse.Read(downBuffer, 0, downBuffer.Length)) > 0
How can I divide a file to be downloaded into multiple segments, so that I can download separate segments in parallel and merge them?
using (WebClient wcDownload = new WebClient())
{
try
{
// Create a request to the file we are downloading
webRequest = (HttpWebRequest)WebRequest.Create(txtUrl.Text);
// Set default authentication for retrieving the file
webRequest.Credentials = CredentialCache.DefaultCredentials;
// Retrieve the response from the server
webResponse = (HttpWebResponse)webRequest.GetResponse();
// Ask the server for the file size and store it
Int64 fileSize = webResponse.ContentLength;
// Open the URL for download
strResponse = wcDownload.OpenRead(txtUrl.Text);
// Create a new file stream where we will be saving the data (local drive)
strLocal = new FileStream(txtPath.Text, FileMode.Create, FileAccess.Write, FileShare.None);
// It will store the current number of bytes we retrieved from the server
int bytesSize = 0;
// A buffer for storing and writing the data retrieved from the server
byte[] downBuffer = new byte[2048];
// Loop through the buffer until the buffer is empty
while ((bytesSize = strResponse.Read(downBuffer, 0, downBuffer.Length)) > 0)
{
// Write the data from the buffer to the local hard drive
strLocal.Write(downBuffer, 0, bytesSize);
// Invoke the method that updates the form's label and progress bar
this.Invoke(new UpdateProgessCallback(this.UpdateProgress), new object[] { strLocal.Length, fileSize });
}
}
you need several threads to accomplish that.
first you start the first download thread, creating a webclient and getting the file size. then you can start several new thread, which add a download range header.
you need a logic which takes care about the downloaded parts, and creates new download parts when one finished.
http://msdn.microsoft.com/de-de/library/system.net.httpwebrequest.addrange.aspx
I noticed that the WebClient implementation has sometimes a strange behaviour, so I still recommend implementing an own HTTP client if you really want to write a "big" download program.
ps: thanks to user svick
I have tried to implement a REST WCF in order to explore difference between PUT and POST verb. I have uploded a file in a location using the service.
The service implementation is as folowing:
[OperationContract]
[WebInvoke(UriTemplate = "/UploadFile", Method = "POST")]
void UploadFile(Stream fileContents);
public void UploadFile(Stream fileContents)
{
byte[] buffer = new byte[32768];
MemoryStream ms = new MemoryStream();
int bytesRead, totalBytesRead = 0;
do
{
bytesRead = fileContents.Read(buffer, 0, buffer.Length);
totalBytesRead += bytesRead;
ms.Write(buffer, 0, bytesRead);
} while (bytesRead > 0);
using (FileStream fs = File.OpenWrite(#"C:\temp\test.txt"))
{
ms.WriteTo(fs);
}
ms.Close();
}
Client code is as following:
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("http://localhost:1922 /EMPRESTService.svc/UploadFile");
request.Method = "POST";
request.ContentType = "text/plain";
byte[] fileToSend = File.ReadAllBytes(#"C:\TEMP\log.txt"); // txtFileName contains the name of the file to upload.
request.ContentLength = fileToSend.Length;
using (Stream requestStream = request.GetRequestStream())
{
// Send the file as body request.
requestStream.Write(fileToSend, 0, fileToSend.Length);
//requestStream.Close();
}
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
Console.WriteLine("HTTP/{0} {1} {2}", response.ProtocolVersion, (int)response.StatusCode, response.StatusDescription);
Console.ReadLine();
The file is being uploaded and the response status code is being returned as "200 OK". The satus code is same in case of existance or non-existance of the file in the upload location.
I have changed the REST verb to PUT and the status code is same as above.
Could anybody explain, how I can identify the differences between the verbs in this context? I couldn't able to simulate generating continious request fron client code. If the behaviour will differ on doing so, could anybody help me in modifying the client code in ordrr to send continious request in a row ?
POST verb is used when are you creating a new resource (a file in your case) and repeated operations would create multiple resources on the server. This verb would make sense if uploading a file with the same name multiple times creates multiple files on the server.
PUT verb is used when you are updating an existing resource or creating a new resource with a predefined id. Multiple operations would recreate or update the same resource on the server. This verb would make sense if uploading a file with the same name for the second, third... time would overwrite the previously uploaded file.