Open Source Document Management System | OpenKM

I am C# developer and I want to know if I can search for a document by property group and if yes can you give me simple example.
and another question can I add a link ( I mean menu tab beside the help tab or search tab ) in open km user interface so I can show the user when clicking on it an entry form (customizing in user interface)

and thank you very much

Have you tried the OpenKM SDK? It's quite simple.

yes I already used it but I want to know where is the search function that will help me search for a document by a property group

any reply ?

Here http://wiki.openkm.com/index.php/Csharp_webservice_dll you got methods to search, for example