Excel files can use open format based on Open XML standard, but it has nothing to do with W3 standards and is foreign to the Web.
There is no such concept as "embedding". You can simply store Excel and other office files on the server. To present them, you have to use HTML. You can develop some mapping between your dynamic HTML representing, say, a spreadsheet, and Excel document. This is quite possible to implement based, in particular, on ASP.NET
System.Web.UI.WebControls.GridView:
https://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridview%28v=vs.110%29.aspx.
Is some page or on some HTTP request, you can open requested Excel document on the server side, read it and create some data source out of it, create and populate a grid view. You can bind the data source with the grid view (
https://msdn.microsoft.com/en-us/library/fkx0cy6d(v=vs.110).aspx). If the document is supposed to be read/write, you can generate a new Excel file based on the updated data source.
To work with data, I would recommend to use Microsoft Open XML SDK (and not Office interop). Please see this CodeProject article:
Creating basic Excel workbook with Open XML.
See also Microsoft warnings against using Office interop in server sittings:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q257757#kb2,
http://support.microsoft.com/kb/257757/en-us.
See also my past answer with references to other answers and other links:
How to add microsoft excel 15.0 object library from Add Reference in MS Visual Studio 2010.
—SA
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