Hi Guys
I am trying to create a web app to share docs with all editor features (just like google docs).
My main requirements for this app are as follows:
1. Should have all editor features (can be done using open office api, google docs api, Microsoft office web apps api)
2. Should be shared between multiple users and can be edited by multiple users and other sync features (can be done using google docs api, Microsoft office web apps)
3. Can save the document created and edited on my own/ custom server addr. (Which api can support this??? I know open office can support this)

Guys can you please suggest me one api which can be used to do all the above. Also please suggest if I am underestimating any API above regarding any functionality that i thing is not supported.

Thanks
King