Coming up with time/staff required estimates for converting a desktop app into a client-server app

Question

My boss is bidding on a project to convert a desktop application into one that runs online as a client-server application. The original app has a little more than a quarter of a million lines of C++ (MFC) code that's not cleanly divided between engine and front-end.

I need to come up with estimates of how long it will take and how many people would be needed for such a project. We don't have anyone on staff capable of doing this project, and we don't have any Windows machines, so we'd have to subcontract/outsource.

Alternatively, what arguments can I use to convince my boss that this project is a bad idea?

Answer 1

Without a clear division between the engine and the front-end, it's a bad idea. Giving over the code to a contractor or such would require a large amount of training just to understand the code, including parts that are meant to be rewritten as web apps.

You would first need to estimate how long it would take to clearly define that boundary, and then you can work out how long the rest of the project would take. That way you can train the contractor etc. on the parts that relate to the presentation tier and the API for the engine without explaining how the engine works (which should be irrelevant to the presentation components).

Answer 2

I would take a very long time, as most likely, you would have to change languages. It would basically be a complete rewrite. You may even just be better off defining what the old system did, and rewrite it from scratch, only referring to the old code when you need to duplicate business logic.

Answer 3

give the info to qualified consultants/outsourcers (send it to me, for example) and consider the ROI based on their estimates

it definitely sounds like you don't have the ability to do this efficiently in-house, but that doesn't mean that it is a bad idea - it depends on the ROI

for example, if your boss thinks this thing could generate $1M in revenue in the first year and a contractor could do the conversion in 6 months for $250K, the ROI (300% in 18 months) is probably good enough to do it

if the numbers are reversed, then it is obviously a Bad Idea ;-)

Answer 4

This sounds like a job for COCOMO II. COCOMO has been used successfully to estimate size and cost and staff size but it could be a pain. It requires a lot of details and time. But it does answer the question of how to go about estimating the size of the project and the number of people required and the time it will take.

Answer 5

The only way to properly estimate this is to give it to someone who 1. will be working on it; and 2. understands the language it's in as well as the language you are converting to.

Regardless, it is ALWAYS a BAD IDEA to bid on projects for which you have no experience. Every single time I've seen someone do that they badly underbid it. Not just in terms of the amount of work required, but also in the learning curve necessary to even begin to understand the underlying processes.

Especially beware of bidding a project you have no experience for then explicitly telling a subcontractor what their budget is to get a project done. I would never work under those conditions, again, because 100% of the time the person doing the bidding is going to get it way wrong.

One more thing, if it's a desktop app, with a backend, then it's already client server... Are you meaning to take an existing client/server app and convert it to a web app?