Annotations (Note, Text, Rectangle, Line ...) at a PDF document.

We have a web based document management system developed in .NET. We use Ghost Script to convert the documents in PDF to display them (viewer). We want to insert annotations to that PDF documents. It should work same as [login to view URL] We just need the following functions (see also the attached file): 1. Sticky Note 2. Text Edit 3. Highlight Rectangle 4. Line 5. Arrow 6. Freehand 7. Filled Rectangle 8. Filled Ellipse 9. Filled Polygon 10. Rectangle 11. Ellipse 12. Polygon After inserting the annotations user can save the document. Original document or PDF should not be changed by inserting annotations (May be annotations are on a separate layer?). Only user who has the right to edit the document, will see the annotation icons (edit right is already existing in the software). These users can also edit and delete the annotations.