Running Excel calculation on a server remotely, as a calculation engine.

Originally Posted by Keebellah

You speak of over a period of some twenty tears so may I assume that the Excel version it was created in is previous to Excel 2007?
That would mean that the Excel file has the extension xlsx?

It's been developed continuously over twenty years, so it has been re-saved with the .xls extension at some point. It currently has the .xls extension.

Originally Posted by Keebellah

You can use other file's code if you open it in the background, and if you just need it to read data you can open it as read-only so that others can access it too, but with the minimal explanation you have given and no idea whatsoever the 'intricate' file looks like and what kind of calculations you want to carry out it's difficult to say.

I think that you misunderstand what I am trying to achieve here. A do literally want to "[Run the] Excel calculation on a server remotely, as a calculation engine". As the file is hugely complex it's not possible to re-implement in a reasonable period of time. It contains a lot of intricate engineering calculations. So rather than try to re-implement it in a programming language, I want to treat the whole excel sheet as a function; i.e. I take some input data from a user via a javascript application running in a webpage, send that to my code on the server, supply the input parameters to the spreadsheet (there are approximately 300), allow it to calculate the results (it calculates 14 separate model scenarios and each has a couple dozen output parameters), then read out all those output parameters and send them back to the application running in the webpage and display them.

While I appreciate that "rewrite it in a programming language" is a potential default response here, I can assure you I've tried and the complexity of the task is simply too high.

Originally Posted by Keebellah

Another thing that would be good to know for us is what is your level of macro knowledge (VBA).

I'm fully familiar with macros, but this is rather a red herring as I'm not trying to do anything within the sheet itself - I want to run the sheet externally via code that I write. FYI, I'm a software engineer.

Originally Posted by Keebellah

It might also be a project which is a lot more that just help but design and rewrite.

It's definitely a massive project that I am in the middle of. But I only have a narrow question for you here: what are the options for taking an Excel spreadsheet and running it remotely as a calculation engine?