Hi,
Yes. You can do both.
Here is a working example for downloading without saving into a file:
http://demo.essentialobjects.com/Default.aspx?path=Downloader\_i0\_i4You can take a look of the sample source code to see how it works. Basically you get a writer with which you can write out your download contents to the client directly. While it does not create physical file on your server, you still need to specify a file name. The name itself is not very important, but the extension for this name is important because that's what the browser uses to determine what program it uses to open the download.
You do not need our uploader to upload a file without saving into a file. The standard ASP.NET FileUpload control works that way. The very reason that user uses our uploader control is because our control streams upload contents into a file. This is very important so that it can handle large uploads. ASP.NET FileUpload can not handle large upload because it keeps the whole file in memory (thus it is not exactly a memory "stream", but a huge memory block).
Even though our uploader does write into physical files, it is done through temp files and it automatically cleans them. So all you need to do is to provide it a writable directory. Once user uploads a file, you will get a temp file name, you can then do whatever you'd like with that file and once you are done, the file will be automatically deleted by the uploader.
Please feel free to let us know if you have any more questions.
Thanks!