1. Front End VFP, Middle Tier VFP, Backend SQL Server 2005

I'm sure some will say that since you have to rewrite anyway, you might as well do it in another language, but there is more to it than that. Based on your years of experience with VFP and the fact that the existing code is in Fox, this is the quickest and least expensive path to your destination. It also makes it possible to rewrite/refactor sections of the system instead of doing the whole thing at once. At the end of the project, you'll still be with VFP, so you have to decide if that's best for your company.

2. Front End C#, Middle Tier VFP, Backend SQL Server 2005

As a total rewrite strategy, this option is not very appealing. Just like Fox works best with Fox, .NET works best with .NET. You may find that some processes are better done in Fox, and you could maintain those as COM objects, but I think that should be the exception and not the rule.

However, total rewrite may not be the only strategy available. You mentioned that the original app may be kept in production, and many Fox developers don't see a compelling reason to move to WinForms. In this context, all of a sudden this option is looking pretty good. Putting an ASP.NET front end on the existing app is probably not a bad business decision, but I'm not sure if that meets all of your goals.

3. Front End C#, Middle Tier C#, Backend SQL Server 2005

If you are looking to keep up with the current and future technologies coming out of Microsoft, then this may be your best option. Microsoft has stated pretty clearly that their future is in managed code. Sedna will help VFP apps interop with the new stuff, but it won't be the same as being on the .NET platform. That said, you are literally talking about a complete rewrite. The costs associated with the learning curve and rewriting code in a different language will be higher than sticking with Fox, IMO. You could say that this is an investment in the future, which I won't argue, but realize that it is an additional investment up front.

When looking at costs, be sure to think about what your real requirements are. For example, does choosing option 1 also mean that you'll have to do option 2? Perhaps option 3 is less expensive than options 1 & 2 combined. It's a tough decision. I'm glad your company is taking the time to consider all options.

>I have been tasked to create a white paper for inhouse use to look at the business considerations in rewriting a major application (took 10 years to develop completely and is now in VFP9 but still has data handling code throughout accessing tables directly - no ntier development but many classes and new features have been added overtime) from VFP to C# using SQL Server 2005 as a backend. WOW.
>
>I have six weeks to complete it. A lot to consider and right now I am looking at the below options to include:
>
>Front End VFP, Middle Tier VFP, Backend SQL Server 2005
>Front End C#, Middle Tier VFP, Backend SQL Server 2005
>Front End C#, Middle Tier C#, Backend SQL Server 2005
>
>
>Right now there is no TRUE middle tier but if it is rewritten then it should be done with one to allow for the greatest options down the road for future modifications.
>
>using C# it would include options of winforms or webforms
>
>If we do this, then the company will invest in formal C# training (wow, what a terrific opportunity). Right now I only have my experience learning on my own at home).
>
>I know the benefits of using VFP data handling but there are many business cases for creating a separate dotnet frontend and even using data handling in net (yuck but it must be seriously considered). I do not have to present that information other than to list the pros and cons but will focus on the benefits and drawbacks (as a business, as developers, and from the customers perspective - sales) of each option listed above and the estimated manhours to complete each one. The original app may still exist if the rewritten one is strictly thin client. That will be determined as well. We have over a thousand customers so the need for thin and thick clients exist.
>
>Please do not respond with "WHY even consider this?" The task was assigned and I will do my best to complete it honestly and in a professional manner listing all aspects.
>
>Previous documentation and experience anyone is willing to share would be GREATLY appreciated.