To view and edit DWG files on browser

Question

I need to do the following

1. User will login to my application and upload AutoCAD file
2. User will open the file at later date to view and edit within the browser
3. User will need the ability to Redline the document. This includes ability to draw lines and basic shapes on the top of document.
4. User will save the revised AutoCAD file in .dwg format

I am looking for a third party development Tool Kit or API hat will allow me to
1.Display AutoCAD file within browser
2.Allow user to draw on top of it

Note: I cannot install anything on my client machine however browser plugin is acceptable.
Any help will be appreciated.