Develop Reference

C#- Renci.Ssh.Net- Which one gives optimized performance- WriteAllText Vs. UploadFile

I need to generate multiple XML files at SFTP location from C# code. for SFTP connectivity, I am using Renci.Ssh.net. I found there are different methods to generate files including WriteAllText() and UploadFile(). I am producing XML string runtime, currently I've used WriteAllText() method (just to avoid creating the XML file on local and thus to avoid IO operation).
using (SftpClient client = new SftpClient(host,port, sftpUser, sftpPassword))
{
client.Connect();
if (client.IsConnected)
{
client.BufferSize = 1024;
var filePath = sftpDir + fileName;
client.WriteAllText(filePath, contents);
client.Disconnect();
}
client.Dispose();
}
Will using UploadFile(), either from FileStream or MemoryStream give me better performance in long run?
The result document size will be in KB, around 60KB.
Thanks!

SftpClient.UploadFile is optimized for uploads of large amount of data.
But for 60KB, I'm pretty sure that it makes no difference whatsoever. So you can continue using the more convenient SftpClient.WriteAllText.
Though, I believe that most XML generators (like .NET XmlWriter are able to write XML to Stream (it's usually the preferred output API, rather than a string). So the use of SftpClient.UploadFile can be more convenient in the end.
See also What is the difference between SftpClient.UploadFile and SftpClient.WriteAllBytes?

Use PdfReport.Core in a WEB-API .NET CORE 2

I am looking into PdfReport.Core and have been asked to let our .NET CORE 2.0 WEB-API return a PDF to the calling client. The client would be any https caller like a ajax or mvc client.
Below is a bit of the code I am using. I am using swashbuckle to test the api, which looks like it is returning the report but when I try to open in a PDF viewer it says it is curropted. I am thinking I am not actually outputting the actual PDF to the stream, suggestions?
[HttpGet]
[Route("api/v1/pdf")]
public FileResult GetPDF()
{
var outputStream = new MemoryStream();
InMemoryPdfReport.CreateStreamingPdfReport(_hostingEnvironment.WebRootPath, outputStream);
outputStream.Position = 0;
return new FileStreamResult(outputStream, "application/pdf")
{
FileDownloadName = "report.pdf"
};
}

I'm not familiar with that particular library, but generally speaking with streams, file corruption is a result of either 1) the write not being flushed or 2) incorrect positioning within the stream.
Since, you've set the position back to zero, I'm guessing the problem is that your write isn't being flushed correctly. Essentially, when you write to a stream, the data is not necessarily "complete" in the stream. Sometimes writes are queued to more efficiently write in batches. Sometimes, there's cleanup tasks a particular stream writer needs to complete to "finalize" everything. For example, with a format like PDF, end matter may need to be appended to the bytes, particular to the format. A stream writer that is writing PDF would take care of this in a flush operation, since it cannot be completed until all writing is done.
Long and short, review the documentation of the library. In particular, look for any method/process that deals with "flushing". That's most likely what your missing.

Write the contents of Response.OutputStream also to a text file before replying back to the client

I am using
using (StreamWriter writer = new StreamWriter(Response.OutputStream, System.Text.Encoding.UTF8));
In order to directly write some lines of text and send them to the browser as an attachment.
I now though also want to save that text locally in a file, but Id rather avoid changing too much of my code. Can I write the contents of Response.OutputStream into a text file before ending the response?

I believe what you ask for is not doable. I am quite sure Response.OutpuStream is not seekable (property CanSeek yielding false), meaning you won't be able to get at its start for reading its content. It is probably not readable either (property CanRead yielding false).
Attempting any of those operations would yield a NotSupportedException.
If your needs are for some basic logging, you may work around that by enabling .Net standard network traces. Or code an IHttpModule as suggested here.
Otherwise, you may use an intermediate MemoryStream with your StreamWriter, then reset this MemoryStream to Position 0, write it to OutputStream, reset it again to Position 0, write it to your file.

You can use the CopyTo method of the Stream object. At the end you can copy the whole OutputStream to an other one which write it to a file. (https://msdn.microsoft.com/en-us/library/dd782932(v=vs.110).aspx)

ICSharpCode.SharpZipLib.Zip example with crc variable details

I am using icsharpziplib dll for zipping sharepoint files using c# in asp.net
When i open the output.zip file, it is showing "zip file is either corrupted or damaged".
And the crc value for files in the output.zip is showing as 000000.
How do we calculate or configure crc value using icsharpziplib dll?
Can any one have the good example how to do zipping using memorystreams?

it seems you're not creating each ZipEntry.
Here's is a code that I adapted to my needs:
http://wiki.sharpdevelop.net/SharpZipLib-Zip-Samples.ashx#Create_a_Zip_fromto_a_memory_stream_or_byte_array_1
Anyway with SharpZipLib there are many ways you can work with zip file: the ZipFile class, the ZipOutputStream and the FastZip.
I'm using the ZipOutputStream to create an in-memory ZIP file, adding in-memory streams to it and finally flushing to disk, and it's working quite good. Why ZipOutputStream? Because it's the only choice available if you want to specify a compression level and use Streams.
Good luck :)

1:
You could do it manually but the ICSharpCode library will take care of it for you. Also something I've discovered: 'zip file is either corrupted or damaged' can also be a result of not adding your zip entry name correctly (such as an entry that sits in a chain of subfolders).
2:
I solved this problem by creating a compressionHelper utility. I had to dynamically compose and return zip files. Temp files were not an option as the process was to be run by a webservice.
The trick with this was a BeginZip(), AddEntry() and EndZip() methods (because I made it into a utility to be invoked. You could just use the code directly if need be).
Something I've excluded from the example are checks for initialization (like calling EndZip() first by mistake) and proper disposal code (best to implement IDisposable and close your zipfileStream and your memoryStream if applicable).
using System.IO;
using ICSharpCode.SharpZipLib.Zip;
public void BeginZipUpdate()
{
_memoryStream = new MemoryStream(200);
_zipOutputStream = new ZipOutputStream(_memoryStream);
}
public void EndZipUpdate()
{
_zipOutputStream.Finish();
_zipOutputStream.Close();
_zipOutputStream = null;
}
//Entry name could be 'somefile.txt' or 'Assemblies\MyAssembly.dll' to indicate a folder.
//Unsure where you'd be getting your file, I'm reading the data from the database.
public void AddEntry(string entryName, byte[] bytes)
{
ZipEntry entry = new ZipEntry(entryName);
entry.DateTime = DateTime.Now;
entry.Size = bytes.Length;
_zipOutputStream.PutNextEntry(entry);
_zipOutputStream.Write(bytes, 0, bytes.Length);
_zipOutputStreamEntries.Add(entryName);
}
So you're actually having the zipOutputStream write to a memoryStream. Then once _zipOutputStream is closed, you can return the contents of the memoryStream.
public byte[] GetResultingZipFile()
{
_zipOutputStream.Finish();
_zipOutputStream.Close();
_zipOutputStream = null;
return _memoryStream.ToArray();
}
Just be aware of how much you want to add to a zipfile (delay in process/IO/timeouts etc).

The process cannot access the file <filepath> because it is being used by another process

I'm upload big files dividing its on chunks(small parts) on my ASMX webservice(asmx doesn't support streaming, I not found another way):
bool UploadChunk(byte[] bytes, string path, string md5)
{
...
using (FileStream fs = new FileStream(tempPath, FileMode.Append) )
{
fs.Write( bytes, 0, bytes.Length );
}
...
return status;
}
but on some files after ~20-50 invokes I catch this error: The process cannot access the file because it is being used by another process.
I suspect that this related with Windows can't realize the file. Any idea to get rid of this boring error?
EDIT
the requests executes sequentially and synchronously
EDIT2
client code looks like:
_service.StartUpload(path);
...
do
{
..
bool status = _service.UploadChunk(buf, path, md5);
if(!status)return Status.Failed;
..
}
while(bytesRead > 0);
_service.CheckFile(path, md5);

Each request is handled independently. The process still accessing the file may be the previous request.
In general, you should use file transfer protocols to transfer files. ASMX is not good for that.
And, I presume you have a good reason to not use WCF?

Use WhoLockMe at the moment the error occurs to check who is using the file. You could put the application into debug mode and hold the break point to do this. In all probability it will be your process.
Also try adding a delay after each transfer (and before the next) to see if it helps. Maybe your transfers are too fast and the stream is still in use or being flushed when the next transfer comes in.

Option 1: Get the requirements changed so you don't have to do this using ASMX. WCF supports a streaming model that I'm about to experiment with, but it should be much more effective for what you want.
Option 2: Look into WSE 3.0. I haven't looked at it much, but I think it extends ASMX web services to support things like DIME and MTOM which are designed for transferring files so that may help.
Option 3: Set the system up so that each call writes a piece of the file into a different filename, then write code to rejoin everything at the end.

use this for creating a file
if you want to append something then add FileMode.Append
var filestreama = new FileStream(name, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);