Excel as a calculation engine on the web?

I have an existing business application written in Excel which the client would like to mak开发者_开发知识库e accessible on the web.

I started off thinking I would have to reimplement it, however it has occurred to me that it would make the job much easier, maintain the knowledge and value in the spreadsheet and make the new tool more flexible if I could connect the existing spreadsheet as a data source from ASP.NET and use it as an engine.

This sounded like a good solution until I considered that Excel would spawn a new process for each connection and we would likely get locking issues.

Is this assumption correct? Is there a component that I could use to manage this?

Note: I have seen Excel Services but Sharepoint is not an option. The application will be a public facing website but only some users will be allowed to access the application. Conservative estimate: 1000 monthly active users of which half have paid to access the application.

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Office automation is NOT supported by MS in this scenario...

MS provides the OpenXML SDK V 2.0 - see http://msdn.microsoft.com/en-us/library/bb448854%28office.14%29.aspx

This can read+write MS Office files (including Excel)...

Another option see http://www.codeproject.com/KB/office/OpenXML.aspx

IF you need more like rendering, formulas etc. then there are different commercial libraries like Aspose.Cells and Flexcel and Spreadsheetgear...

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For the usage you describe even if it's only read only access to the information, excel is not designed for this and I foresee problems. I would strongly recommend you import the excel information into a DB and write code to access it!

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There are a number of Excel calculation engines offered by third parties that are designed to be able to be used on the server. A couple that come to mind are Aspose Cells and SpreadsheetGear.