hi do any one can create documents editor on website

We are planning to create a documents store in a browser (with PHP language), where a user can open a document (word, excel etc.) in something like "Google docs", "Word online" or similar (from now i call this "the webstore"), then edit the document, and then save it back to our document store (from now i call this "OUR store"). The documents store must be saved on our own server. It is not acceptabul to use "the webstore" as a store, temporarily is ok, but the permanent store must be "OUR store". So my idea is to do this like this: 1) the user opens the document on the website (from "OUR store") and it opens in "the webstore" editor in the browser 2) the user edits the document 3) the user saves the document to "the webstore" 4) in the background we download the edited document from "the webstore", and save it to "OUR store" In my idea i think we need to use some kind of "the webstore" API to get access to download the edited file. So what i need is someone who can create a prototype on how we can do number 1 to 4 above. You can just set up a php script/website yourself, that we can use to implement on our site.