Stream pdfs from url and add it to Zip - pdf

Question

I have a mvc 4.5 application where I show a grid. The first column of the grid is a document name. The document name is an hyper link to the actual document that is hosted on our site and is available via a url. The documents can be pdf or doc or ppt. I can access these documents only via url and I do not have access to the actual physical document on our server.
I am providing users an option to select one or many of these documents from the grid and then they can download them. What I am trying to achieve is read each of the selected documents via the url and write it to a zip file and make the zip file downloadable. So users will be downloading one file instead of multiple files.
I have tried to stream the documents via url in memory and then add it to the zip file using ZipArchive Library from Microsoft. This is not working for me.
I was able to add documents that was on disk to zip file using Zip Archive and it works great. But I do not have access to the physical document as I can access the documents only through URL. My next option is to download each of these documents into a temp location on server and then add it to zip file using Zip Archive.But I am trying to avoid downloading files into a temp location
Please suggest how I can achieve reading documents via url in memory and adding each of these document to zip file and make zip file downloadable.
Any help will be appreciated.

Answer 1

Thank you Cbroe for commenting. I figured the answer. The problem was I was reading the pdf from the url and convert it to a memory stream and then was trying to add the memory stream to ZipArchive which was not working but instead I extracted the byte array out of the memory stream and then added it to the zip archive and it worked.
Here is the code snippet that might be useful for some one. My first contribution to Stack OverFlow.
public FileResult DownloadZip()
{
MemoryStream memoryStream = new MemoryStream();
using (var archive = new ZipArchive(memoryStream, ZipArchiveMode.Create, true))
{
var demoFile = archive.CreateEntry("Pdf123.pdf");
var convertedStream = ConvertTobyte("http://www.example.com/Pdf123.pdf");
using (var entryStream = demoFile.Open())
{
entryStream.Write(convertedStream, 0, convertedStream.Length);
}
demoFile = archive.CreateEntry("Pdf456.pdf");
convertedStream = ConvertTobyte("http://www.example.com/Pdf456.pdf");
using (var entryStream = demoFile.Open())
{
entryStream.Write(convertedStream, 0, convertedStream.Length);
}
}
//This option is to write the zip to your local disk
using (var fileStream = new FileStream(#"C:\Temp\test.zip", FileMode.Create))
{
memoryStream.Seek(0, SeekOrigin.Begin);
memoryStream.CopyTo(fileStream);
}
//This option is to donload the zip via browser
memoryStream.Seek(0, SeekOrigin.Begin);
return new FileStreamResult(memoryStream, "application/zip")
{
FileDownloadName = "Archive.zip"
};
}
private static byte[] ConvertTobyte(string fileUrl)
{
byte[] imageData = null;
using (var wc = new System.Net.WebClient())
imageData = wc.DownloadData(fileUrl);
return imageData;
}