Create zip in .net Core from URLS without downloading on server

Question

I have list of internet URLS I am trying to create a zip using Memorystream. The files are on s3 bucket however s3 sdk doesnt have any function to download folder as zip.

Avoiding to save it on server and delete those. The project is running on Ubuntu. I have tried getting the response as follows,

var httpClient = new HttpClient();
httpClient.DefaultRequestHeaders.UserAgent.Add(new ProductInfoHeaderValue("MyClient", "1.0"));
var result = await httpClient.GetStreamAsync(names[0]);

However the ZipArchive class in .NET takes local files path and not memorystream

Note: I cannot use SharpZipLib since it is not supported by .NET Core.

Answer 1

However the ZipArchive class in .NET takes local files path and not memorystream

This is untrue, the ZipArchive class has overloads that accept Stream instances:

https://msdn.microsoft.com/en-us/library/hh158268(v=vs.110).aspx

Initializes a new instance of the ZipArchive class from the specified stream.

public ZipArchive(Stream stream)

(Documentation is for the full .NET Framework, but the .NET Core implementation has the same interface: https://github.com/dotnet/corefx/blob/master/src/System.IO.Compression/src/System/IO/Compression/ZipArchive.cs )

Like so:

class ItemToAdd {
    public String Name;
    public Stream Content;
}

List<ItemToAdd> itemsToAdd = GetItemsFromAmazonS3();

using( MemoryStream zipStream = new MemoryStream() ) {
    
    using( ZipArchive zip = new ZipArchive( zipStream, ZipArchiveMode.Create ) ) {
    
        foreach( ItemToAdd item in itemsToAdd ) {
        
            ZipArchiveEntry entry = zip.CreateEntry( item.Name );
            using( Stream entryStream = entry.Open() ) {
                
                item.Content.CopyTo( entryStream );
            }
        }

    }
    
    zipStream.Position = 0;

    // copy zipStream to output, or return it directly depending on your web framework
}

Answer 2

This is how xml Doc can be zipped and uploaded to aws S3, hope will help someone.

var stMarged = new System.IO.MemoryStream();
Doc.Save(stMarged);


stMarged.Position = 0;
using (MemoryStream zipStream = new MemoryStream())
{
    using (ZipArchive zip = new ZipArchive(zipStream, ZipArchiveMode.Create, true))
    {
        ZipArchiveEntry entry = zip.CreateEntry("propertyFeed.xml");

        using (Stream entryStream = entry.Open())
        {
            stMarged.CopyTo(entryStream);
        }

        //Not the best way but the file is smaler 
        //ZipArchiveEntry entry1 = zip.CreateEntry("propertyFeed1.xml");
        //using (StreamWriter writer = new StreamWriter(entry1.Open()))
        //    writer.Write(Doc2.OuterXml);
    }

    zipStream.Position = 0;
    aa += UploadZipStreamToS3(zipStream);
}