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C# gRPC file streaming, original file smaller than the streamed one

I am having some problems with setting up a request-stream type gRPC architecture. The code below is just for testing purposes and it is missing various validation checks, but the main issue is that the original file is always smaller than the received one.
Could the cause here be encoding? It doesn't matter what the file type is, the end result is always that the file sizes are different.
Protobuf inteface:
syntax = "proto3";
package FileTransfer;
option csharp_namespace = "FileTransferProto";
service FileTransferService {
rpc DownloadFile(FileRequest) returns (stream ChunkMsg);
}
message ChunkMsg {
string FileName = 1;
int64 FileSize = 2;
bytes Chunk = 3;
}
message FileRequest {
string FilePath = 1;
}
Server side (sending):
public override async Task DownloadFile(FileRequest request, IServerStreamWriter<ChunkMsg> responseStream, ServerCallContext context)
{
string filePath = request.FilePath;
if (!File.Exists(filePath)) { return; }
FileInfo fileInfo = new FileInfo(filePath);
ChunkMsg chunk = new ChunkMsg();
chunk.FileName = Path.GetFileName(filePath);
chunk.FileSize = fileInfo.Length;
int fileChunkSize = 64 * 1024;
byte[] fileByteArray = File.ReadAllBytes(filePath);
byte[] fileChunk = new byte[fileChunkSize];
int fileOffset = 0;
while (fileOffset < fileByteArray.Length && !context.CancellationToken.IsCancellationRequested)
{
int length = Math.Min(fileChunkSize, fileByteArray.Length - fileOffset);
Buffer.BlockCopy(fileByteArray, fileOffset, fileChunk, 0, length);
fileOffset += length;
ByteString byteString = ByteString.CopyFrom(fileChunk);
chunk.Chunk = byteString;
await responseStream.WriteAsync(chunk).ConfigureAwait(false);
}
}
Client side (receiving):
public static async Task GetFile(string filePath)
{
var channel = Grpc.Net.Client.GrpcChannel.ForAddress("https://localhost:5001/", new GrpcChannelOptions
{
MaxReceiveMessageSize = 5 * 1024 * 1024, // 5 MB
MaxSendMessageSize = 5 * 1024 * 1024, // 5 MB
});
var client = new FileTransferProto.FileTransferService.FileTransferServiceClient(channel);
var request = new FileRequest { FilePath = filePath };
string tempFileName = $"temp_{DateTime.UtcNow.ToString("yyyyMMdd_HHmmss")}.tmp";
string finalFileName = tempFileName;
using (var call = client.DownloadFile(request))
{
await using (Stream fs = File.OpenWrite(tempFileName))
{
await foreach (ChunkMsg chunkMsg in call.ResponseStream.ReadAllAsync().ConfigureAwait(false))
{
Int64 totalSize = chunkMsg.FileSize;
string tempFinalFilePath = chunkMsg.FileName;
if (!string.IsNullOrEmpty(tempFinalFilePath))
{
finalFileName = chunkMsg.FileName;
}
fs.Write(chunkMsg.Chunk.ToByteArray());
}
}
}
if (finalFileName != tempFileName)
{
File.Move(tempFileName, finalFileName);
}
}

To add to Marc's answer, I feel like you can simplify your code a little bit.
using var fs = File.Open(filePath, System.IO.FileMode.Open);
int bytesRead;
var buffer = new byte[fileChunkSize];
while ((bytesRead = await fs.ReadAsync(buffer)) > 0)
{
await call.RequestStream.WriteAsync(new ChunkMsg
{
// Here the correct number of bytes must be sent which is starting from
// index 0 up to the number of read bytes from the file stream.
// If you solely pass 'buffer' here, the same bug would be present.
Chunk = ByteString.CopyFrom(buffer[0..bytesRead]),
});
}
I've used the array range operator from C# 8.0 which makes this cleaner or you can also use the overload of ByteString.CopyFrom which takes in an offset and count of how many bytes to include.

In your write loop, the chunk you actually send is for the oversized buffer, not accounting for length. This means that the last segment includes some garbage and is oversized. The received payload will be oversized by this same amount. So: make sure you account for length when constructing the chunk to send.

I tested the code and modified it to transfer the correct size.
The complete code is available at the following URL: https://github.com/lisa3907/grpc.fileTransfer
server-side-code
while (_offset < _file_bytes.Length)
{
if (context.CancellationToken.IsCancellationRequested)
break;
var _length = Math.Min(_chunk_size, _file_bytes.Length - _offset);
Buffer.BlockCopy(_file_bytes, _offset, _file_chunk, 0, _length);
_offset += _length;
_chunk.ChunkSize = _length;
_chunk.Chunk = ByteString.CopyFrom(_file_chunk);
await responseStream.WriteAsync(_chunk).ConfigureAwait(false);
}
client-side-code
await foreach (var _chunk in _call.ResponseStream.ReadAllAsync().ConfigureAwait(false))
{
var _total_size = _chunk.FileSize;
if (!String.IsNullOrEmpty(_chunk.FileName))
{
_final_file = _chunk.FileName;
}
if (_chunk.Chunk.Length == _chunk.ChunkSize)
_fs.Write(_chunk.Chunk.ToByteArray());
else
{
_fs.Write(_chunk.Chunk.ToByteArray(), 0, _chunk.ChunkSize);
Console.WriteLine($"final chunk size: {_chunk.ChunkSize}");
}
}

stream video in asp.net web api from database

i want to stream video from database through asp.net web api controller. i have done it from static file in my server(below code), but i can't accomplish the database mode.
here is my code (which i got from searching through web)
public class VideosController : ApiController
{
// GET api/values
public HttpResponseMessage Get(string filename)
{
var filePath = HttpContext.Current.Server.MapPath("~") + filename;
if (!File.Exists(filePath))
return new HttpResponseMessage(HttpStatusCode.NotFound);
var response = Request.CreateResponse();
response.Headers.AcceptRanges.Add("bytes");
var streamer = new FileStreamer();
streamer.FileInfo = new FileInfo(filePath);
response.Content = new PushStreamContent(streamer.WriteToStream, "video/mp4");
RangeHeaderValue rangeHeader = Request.Headers.Range;
if (rangeHeader != null)
{
long totalLength = streamer.FileInfo.Length;
var range = rangeHeader.Ranges.First();
streamer.Start = range.From ?? 0;
streamer.End = range.To ?? totalLength - 1;
response.Content.Headers.ContentLength = streamer.End - streamer.Start + 1;
response.Content.Headers.ContentRange = new ContentRangeHeaderValue(streamer.Start, streamer.End,
totalLength);
response.StatusCode = HttpStatusCode.PartialContent;
}
else
{
response.StatusCode = HttpStatusCode.OK;
}
return response;
}
class FileStreamer
{
public FileInfo FileInfo { get; set; }
public long Start { get; set; }
public long End { get; set; }
public async Task WriteToStream(Stream outputStream, HttpContent content, TransportContext context)
{
try
{
var buffer = new byte[65536];
using (var video = FileInfo.OpenRead())
{
if (End == -1)
{
End = video.Length;
}
var position = Start;
var bytesLeft = End - Start + 1;
video.Position = Start;
while (position <= End)
{
// what should i do here?
var bytesRead = video.Read(buffer, 0, (int)Math.Min(bytesLeft, buffer.Length));
await outputStream.WriteAsync(buffer, 0, bytesRead);
position += bytesRead;
bytesLeft = End - position + 1;
}
}
}
catch (Exception ex)
{
// fail silently
}
finally
{
outputStream.Close();
}
}
}
}
this is my HTML code:
<video width="640" height="480" controls="controls">
<source src="/api/Videos/?filename=sample.mp4" type="video/mp4">
</video>
there is a method ready for me (written by someone else) to get a range of file from engine (database) and its code is like this :
public byte[] Engine.DownloadStreamFile(Guid fileId, long from, long length)
i tried to read from this method and write on response output stream, but i couldn't. it seems i can't handle From and To receiving from google chrome. Any thoughts?

Based on the information you've provided, and assuming the method in your Engine class does what one would assume it does by name and signature, you should try replacing the file system stuff with your Engine.DownloadStreamFile method:
// what should i do here?
var bytesRead = video.Read(buffer, 0, (int)Math.Min(bytesLeft, buffer.Length));
// becomes
var bytesRead = Engine.DownloadStreamFile(this.fileId, this.Start, this.End);
You will obviously need to add a fileId field/property to your class instead of the FileInfo you have today.

Serial Ports - There is an error in XML document (5, 3870)

Here I have a class I've created for the purpose of sending text-files and images over a serial port:
public class SendItem
{
private byte[] bytes;
private string _fileName;
private string _extension;
private int bytesSin;
public string Extension
{
get { return _extension; }
set { _extension = value; }
}
public string FileName
{
get { return _fileName; }
set { _fileName = value; }
}
public byte[] Bytes
{
get { return bytes; }
set { bytes = value; }
}
public SendItem()
{
}
public void SendFile(SerialPort serialPort1)
{
if (serialPort1.IsOpen)
{
OpenFileDialog OFDialog = new OpenFileDialog();
OFDialog.Title = "Open File";
OFDialog.Filter = "Text Files (*.txt)" + "|*.txt|All files (*.*)|*.*";
OFDialog.InitialDirectory = #"C:\";
bool? userClickedOK = OFDialog.ShowDialog();
if (userClickedOK == true)
{
serialPort1.DiscardInBuffer();
string chosenFile = OFDialog.FileName;
string ext = Path.GetExtension(OFDialog.FileName);
_extension = ext;
byte[] data = File.ReadAllBytes(chosenFile);
SendItem newSendItem = new SendItem();
newSendItem._extension = ext;
newSendItem._fileName = System.IO.Path.GetFileNameWithoutExtension(chosenFile);
newSendItem.bytes = data;
byte[] view = newSendItem.Serialize();
string test = Convert.ToBase64String(data);
serialPort1.Write(newSendItem.Serialize(), 0, newSendItem.Serialize().Length);
//serialPort1.Write(data, 0, data.Length);
}
}
}
public override string ToString()
{
return string.Format("File: {0}{1}",_fileName, _extension);
}
}
There is quite a few redundant things in the SendFile method, but I ask that it would be ignored in favour of the following issue I keep on having.
Whenever I send a text file or just plain chat text from a textbox, the following block of code is executed without triggering the catch:
void _sPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
SerialPort sp = (SerialPort)sender;
byte[] data = new byte[sp.BytesToRead];
string message = string.Empty;
sp.Read(data, 0, data.Length);
try
{
SendItem receivedObject = data.Deserialize<SendItem>();
File.WriteAllBytes(#"d:\" + receivedObject.FileName + receivedObject.Extension, receivedObject.Bytes);
message = "File has been recieved.";
sp.Write("File sent.");
}
catch (Exception exp)
{
errors = exp.Message;
message = Encoding.UTF8.GetString(data);
}
App.Current.Dispatcher.Invoke(new Action(() => _response.Add("Friend: " + message)));
}
The problem comes in when I try to send an image... It trigger the catch and gives the exception There is an error in XML document (5, 3870).
My serializer and deserializer I've written is as follow:
public static byte[] Serialize<T>(this T source)
{
XmlSerializer serializer = new XmlSerializer(typeof(T));
MemoryStream stream = new MemoryStream();
serializer.Serialize(stream, source);
byte[] buffer = stream.GetBuffer();
stream.Close();
return buffer;
}
public static T Deserialize<T>(this byte[] source)
{
XmlSerializer serializer = new XmlSerializer(typeof(T));
MemoryStream stream = new MemoryStream(source);
T result = (T)serializer.Deserialize(stream);
stream.Close();
return result;
}
Can anyone point out where I'm making my mistake? I've been debugging it for ages and I can't wrap my head around it.
**EDIT:
I am also including the serialised data for an image I tried to send, after looking at it, it appears my Byte might be too big for the serial port - is there any way to adjust this or allow the serial port to take all of the data sent over?
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

It may or may not be the whole problem, but this is definitely a problem:
byte[] buffer = stream.GetBuffer();
That's quite possibly returning more data than you want - because it's not limiting itself to the length of the stream. MemoryStream has the handy MemoryStream.ToArray method to simplify this:
public static byte[] Serialize<T>(this T source)
{
XmlSerializer serializer = new XmlSerializer(typeof(T));
MemoryStream stream = new MemoryStream();
serializer.Serialize(stream, source);
return stream.ToArray();
}
(There's no benefit from closing a MemoryStream that you've created like this - and if you did feel you needed to, you should use a using statement.)
Likewise your Deserialize method can be simplified to:
public static T Deserialize<T>(this byte[] source)
{
XmlSerializer serializer = new XmlSerializer(typeof(T));
return (T) serializer.Deserialize(new MemoryStream(source));
}
Given that you were effectively trying to deserialize "the XML document - and then probably a load of "blank" data, that may well be the issue.
EDIT: Now there's a second problem:
byte[] data = new byte[sp.BytesToRead];
string message = string.Empty;
sp.Read(data, 0, data.Length);
You're assuming that all of the data is ready to read in a single go. That won't be true if there's more data than the buffer size of the serial port. Instead, if you're trying to put multiple "messages" onto what is effectively a stream, you'll need to either indicate the end of a message (and keep reading until you find that) or write the length of the message before the message itself - then when reading, read that length and then make sure you read that many bytes.
This is a standard issue when you try to use a stream-oriented protocol as a message-oriented protocol.

You should use ToByteArray() instead of GetBuffer().

Load File from SDCard

I integrated (this)EPUB Reader reader to my project. It is working fine. & I want to load the file from SDCard instead of Isolated storage of device
To open file from Isolated storage we have IsolatedStorageFileStream like this
IsolatedStorageFileStream isfs;
using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication())
{
try
{
isfs = isf.OpenFile([Path to file], FileMode.Open);
}
catch
{
return;
}
}
ePubView.Source = isfs;
For file in SDcard I tried like this
ExternalStorageDevice sdCard = (await ExternalStorage.GetExternalStorageDevicesAsync()).FirstOrDefault();
// If the SD card is present, get the route from the SD card.
if (sdCard != null)
{
ExternalStorageFile file = await sdCard.GetFileAsync(_sdFilePath);
// _sdFilePath is string that having file path of file in SDCard
// Create a stream for the route.
Stream file = await file.OpenForReadAsync();
// Read the route data.
ePubView.Source = file;
}
Here I am getting exception System.IO.EndOfStreamException
If You want try.. Here is my project sample link
Question : How can I give my file as source to epubView control
Is this is proper way, please give a suggestion regarding this..
Thanks

Although I've not tried your approach, and I cannot say exactly where is an error (maybe file from SD is read async and thus you get EndOfStream, and please keep in mind that as it is said at EPUB Reader Site - it's under heavy developement). Check if after copying the file to ISolatedStorage, you will be able to use it. I would try in this case first copying from SD to Memory stream like this:
ExternalStorageDevice sdCard = (await ExternalStorage.GetExternalStorageDevicesAsync()).FirstOrDefault();
if (sdCard != null)
{
MemoryStream newStream = new MemoryStream();
using (ExternalStorageFile file = await sdCard.GetFileAsync(_sdFilePath))
using (Stream SDfile = await file.OpenForReadAsync())
newStream = await ReadToMemory(SDfile);
ePubView.Source = newStream;
}
And ReadToMemory:
private async Task<MemoryStream> ReadToMemory(Stream streamToRead)
{
MemoryStream targetStream = new MemoryStream();
const int BUFFER_SIZE = 1024;
byte[] buf = new byte[BUFFER_SIZE];
int bytesread = 0;
while ((bytesread = await streamToRead.ReadAsync(buf, 0, BUFFER_SIZE)) > 0)
{
targetStream.Write(buf, 0, bytesread);
}
return targetStream;
}
Maybe it will help.

There's a bug with the stream returned from ExternalStorageFile. There's two options to get around it...
If the file is small then you can simply copy the stream to a MemoryStream:
Stream s = await file.OpenForReadAsync();
MemoryStream ms = new MemoryStream();
s.CopyTo(ms);
However, if the file is too large you'll run in to memory issues so the following stream wrapper class can be used to correct Microsoft's bug (though in future versions of Windows Phone you'll need to disable this fix once the bug has been fixed):
using System;
using System.IO;
namespace WindowsPhoneBugFix
{
/// <summary>
/// Stream wrapper to circumnavigate buggy Stream reading of stream returned by ExternalStorageFile.OpenForReadAsync()
/// </summary>
public sealed class ExternalStorageFileWrapper : Stream
{
private Stream _stream; // Underlying stream
public ExternalStorageFileWrapper(Stream stream)
{
if (stream == null)
throw new ArgumentNullException("stream");
_stream = stream;
}
// Workaround described here - http://stackoverflow.com/a/21538189/250254
public override long Seek(long offset, SeekOrigin origin)
{
ulong uoffset = (ulong)offset;
ulong fix = ((uoffset & 0xffffffffL) << 32) | ((uoffset & 0xffffffff00000000L) >> 32);
return _stream.Seek((long)fix, origin);
}
public override bool CanRead
{
get { return _stream.CanRead; }
}
public override bool CanSeek
{
get { return _stream.CanSeek; }
}
public override bool CanWrite
{
get { return _stream.CanWrite; }
}
public override void Flush()
{
_stream.Flush();
}
public override long Length
{
get { return _stream.Length; }
}
public override long Position
{
get
{
return _stream.Position;
}
set
{
_stream.Position = value;
}
}
public override int Read(byte[] buffer, int offset, int count)
{
return _stream.Read(buffer, offset, count);
}
public override void SetLength(long value)
{
_stream.SetLength(value);
}
public override void Write(byte[] buffer, int offset, int count)
{
_stream.Write(buffer, offset, count);
}
}
}
Code is available here to drop in to your project:
https://github.com/gavinharriss/ExternalStorageFileWrapper-wp8
Example of use:
ExternalStorageFile file = await device.GetFileAsync(filename); // device is an instance of ExternalStorageDevice
Stream streamOriginal = await file.OpenForReadAsync();
ExternalStorageFileWrapper streamToUse = new ExternalStorageFileWrapper(streamOriginal);

Why StringWriter.ToString return `System.Byte[]` and not the data?

UnZipFile method writes the data from inputStream to outputWriter.
Why sr.ToString() returns System.Byte[] and not the data?
using (var sr = new StringWriter())
{
UnZipFile(response.GetResponseStream(), sr);
var content = sr.ToString();
}
public static void UnZipFile(Stream inputStream, TextWriter outputWriter)
{
using (var zipStream = new ZipInputStream(inputStream))
{
ZipEntry currentEntry;
if ((currentEntry = zipStream.GetNextEntry()) != null)
{
var size = 2048;
var data = new byte[size];
while (true)
{
size = zipStream.Read(data, 0, size);
if (size > 0)
{
outputWriter.Write(data);
}
else
{
break;
}
}
}
}
}

The problem is on the line:
outputWriter.Write(data);
StringWriter.Write has no overload expecting a byte[]. Therefore, Write(Object) is called instead. And according to MSDN:
Writes the text representation of an object to the text string or stream by calling the ToString method on that object.
Calling ToString on a byte array returns System.byte[], explaining how you get that string in your StringWriter.

The reason is simple:
data is of type byte[]. There is no overload for byte[] on StringWriter so it uses the overload for object. And then calls ToString() on the boxed byte array which simply prints the type.
Your code is equivalent to this:
outputWriter.Write(data.ToString());

theateist,
Looking at the other answers here, I am going to have to agree that the reason for the "ToString()" returning System.Byte[] is because that is what you are putting into it, and everything put into the StringWriter calls it's own "ToString" method when doing so. (i.e. byte[].toString() = "System.byte[]"). In fact the whole idea is that the StringWriter is only ment for writing into a string "buffer" (StringBuilder), so in theory if your file was large enough(bigger than 2048), your output would be "System.Byte[]System.Byte[]" (etc.). Try this to deflate into a memory stream and then read from that stream, may be a better understanding of what you are looking at. (Code not tested, just example).
using (Stream ms = new MemoryStream())
{
UnZipFile(response.GetResponseStream(), ms);
string content;
ms.Position = 0;
using(StreamReader s = new StreamReader(ms))
{
content = s.ReadToEnd();
}
}
public static void UnZipFile(Stream inputStream, Stream outputWriter)
{
using (var zipStream = new ZipInputStream(inputStream))
{
ZipEntry currentEntry;
if ((currentEntry = zipStream.GetNextEntry()) != null)
{
int size = 2048;
byte[] data = new byte[size];
while (true)
{
size = zipStream.Read(data, 0, size);
if (size > 0)
{
outputWriter.Write(data);
}
else
{
break;
}
}
}
}
}
Another idea would actually be to using the endcoding to get the string
public string UnZipFile(Stream inputStream)
{
string tmp;
using(Stream zipStream = new ZipInputStream(inputStream))
{
ZipEntry currentEntry;
if(currentEntry = zipStream.GetNextEntry()) != null)
{
using(Stream ms = new MemoryStream())
{
int size = 2048;
byte[] data = new byte[size];
while(true)
{
if((size = zipStream.Read(data,0,size)) > 0)
ms.Write(data);
else
break;
}
tmp = Encoding.Default.GetString(ms.ToByteArray());
}
}
}
}
return tmp;
}
Or as one last idea, you could actually change your original code to have
outputWriter.Write(Encoding.Default.GetString(data));
Instead of
outputWriter.Write(data);
By the way, please avoid the var keyword in posts, maybe just my pet peev, but code is less readable when utilizing weak types.
StringWriter.Write:MSDN
StringWriter.ToString:MSDN