Upload to ADLS from file stream

I am making a custom activity in ADF, which involves reading multiple files from Azure Storage Blobs, doing some work on them, and then finally writing a resulting file to the Azure Data Lake Store. Last step is where I stop, because as far as I can see, the .NET SDK only allows for uploading from a local file.

Is there any way to to (programmatically) upload a file to ADL Store, where it is not from a local file? Could be a blob or a stream. If not, any workarounds?

Yes, it's possible to upload from Stream, the trick is to create file first and then append your stream to it:

string dataLakeAccount = "DLSAccountName";
var adlsFileSystemClient = new DataLakeStoreFileSystemManagementClient(credentials);
adlsFileSystemClient.FileSystem.Create(dataLakeAccount, filepath, overwrite: true);
adlsFileSystemClient.FileSystem.Append(dataLakeAccount, filepath, stream);