>We have a successful payroll application developed with VFP and DBFs specifically for the laws of Panama. We feel we have a very good handle on the business problem and are looking to rewrite the application with up to date tools.
>
>Requirements:
>1. The update should be able to run in the cloud or in a customer's server and PC if customer requires it.
>2. Though the main processes are normally run from a terminal in the office, the app will receive and provide data access from phones and tablets and who knows what else in the future.

Both of the above pretty much dictate that you will require a web based approach.

>3. Some of the data capture screens provide immediate feedback which requires a lot of computation, such as significant checking of historic data. Stateless web server behavior is not really acceptable.

As Craig mentions this shouldn't be a problem - do as much as you can in javascript and use Ajax to just get updated data from the server when ness.

>4. The tools used should be reliable and expected to have a long life left in them. I am especially bothered by MS's habit of periodically making updates to their tools which require you make substantial changes to your code if you wish to use them. Backward compatibility of updates is something we value.

I've never found this a problem. Newer versions of .NET may add functionality but if you don't need it then you can still target your existing .NET version without any problems. IAC, in nearly all cases your existing code will still work with newer .NET versions - and can be maintained using newer versions of VS

>5. Developer productivity enhancing tools are a key consideration.

As Victor suggests it *might* be worth looking at LightSwitch which seems suited to a simple vertical app (but I'd probably favour using the HTML/WebApi option over Sliverlight/WCF).

And definitely 'bite the bullet' and move the backend away from a VFP database :-{

>All suggestions and comments are welcome.
>
>Thank you very much,
>
>Alex