WebForms / MVC to a Windows Forms programmer

Question

Hi,

First I'd like to make it clear, I'm not looking for a "my tech is better than yours" type of post; this is a real case scenario and I have been faced with this decision. With this in mind, let me explain:

We have a WinForms application. It started in the early .NET 1.0 but the first shipping version was using .NET 1.1. There are layers (like BusinessLayer.dll, Datalayer.dll, Framework.DLL, etc.) but at some point during the "long" development cycle of this application, the "presentation" layer (Win Forms) got infected with some code, thus the "separation between the code and the presentation with code behind" is some sort of myth. Bad practices or whatever, the truth is that the application is there and it works.

Years passed and we had .NET 2.0, we slowly migrated and it mostly worked, had to change a few calls here and there. Last version did the same thing, but for .NET 3.5sp1. We needed some sort of Webservices thing, and decided to use WCF instead. It works fine. But despite all these .NET upgrades, most of the application's codebase is still the same old rock and roll from 5 years ago. We use Gentle.NET (old and unmaintained now) for our dataobjects (it was a blessing 5 years ago!).

Our presentation layer, the winforms, are "nice looking" since we employ 90% of completely gdi+ custom controls. (whenever possible without having to hack the WinAPi). The application is touch based (i.e.: it makes use of the Ink but it doesn't rely on that), but the buttons, labels, etc, everything is "designed" to be used with a tactile device. (TabletPC or Touchscreen). Of course some users use keyboard/mouse.

With all that in mind, and with all this web2.0 and Internet fuzz (plus Jeff's posts ;) ), we are considering the possibility of rewriting the application but using a web technology. The idea is obviously bringing more availability for our customers (they can use the system whenever/wherever they want), and less maintenance (we can upgrade and it is an instant upgrade for 'em all), etc. You know, the usual Internet vs WinApp thingy.

The problem is that given that this is the healthcare industry, not all of our customers might be willing to "move" their databases to our server/s, which is acceptable, and would force us to install a webserver/database server in their own servers so they have their own copy. Not a big problem (except we would have to update those manually but that's not an issue, given that we've been updating win32 apps for 5 years now!).

Now, back to the main "question".

The team has little Asp.NET experience, we did program a lot in ASP 2.0 (in 1999/2000) but that was a spaghetti of HTML+VBScript+CSS, so I don't think it counts. After all that experience (the Internet bubble!) we went back to VB6 then C#.NET 1x and you know the rest of the story. We're a small team of C# developers for WinForms. We've acquired some Linq To SQL Experience in our last .NET 3.5 ride, and we liked it. We felt it very natural and very "if we would have had this five years ago…" like.

Given all this, rewriting the application is not a "simple task" (not even if we wanted to do it in the already known C#.NET), it would take time and planning, but we could correct dozens of mistakes and with 5 years of experience working with the application, we now can say that we have a better idea of how the customers would like to use the software and what limitations we created (by ourselves) when we designed the current app. All that "knowledge" of the application and the way the business works, could be applied to produce a much better application in terms of design and code and usability. Remember in .NET 1.1 we didn't even have generics! ;) (you'll see lots of ArrayList's hanging around here).

As an additional note, we use Crystal Reports (and, as usual, we hate it). We don't think the ink control is a "must" either. The HTML/CSS could be shaped to look the way we want it, although we're aware that HTML is not WinForms (and hence some things cannot be reproduced).

Do you think that planning this in MVC (or WebForms) would be too crazy? I like the MVC (ruby on rails like) idea (I've never programmed in ruby beyond the basics of the book), so no one in our team is an expert, but we can always learn and read. It mustn't be "rocket science", must it?

I know that this whole question might be a little bit subjective, but would you replace an aging Winforms application with a new ASP/MVC/XXX web application? Do you have experience or have tried (and had success or failed) ?

Any insight in helping use better decide what to do will be appreciated.

Thanks in advance!

UPDATE: Thanks to all who responded, we'll evaluate whether this is a good move or not, it sure is a hell of work, but I am afraid the the desktop app is getting older (using old net 1.1 hacks) and tho it has been more or less working without problems in Vista and W7, I'm afraid a future update may break it. Also, lots of "more or less core" parts of the application are exposing some badly designed ideas and we had to hack here and there to accomplish certain tasks. Part inexperience, part lack of 100% knowledge of how the business worked (and Customers not sure what they wanted). A new application (in any form) would allow us to create a better foundation while retaining all the user knowledge. But, it's a L O T of work :) So we'll consider all these options here. As some of you have mentioned, maybe a thinner client and some (ab)use of WCF here and there might be more appropriate.

Once again, thanks to all!

Answer 1

It would be best to ditch all your efforts of reusing the desktop application code when you recreate the web app. Following are the reasons:

1. Web apps especially asp.net use a different model. For starters note http is stateless. Each time the browser talks to server you have to explicitly send the current content of all the controls on the current page. You would not have used such a model in your Windows application.

2. To decrease load on the network you want to optimize the size of viewstate and how frequent you make http requests. Again your existing window app does not have any such provisions.

3. Updating view. You might have different event handlers, threads and what not in your windows application to update the GUI in different scenarios. All of that will need to be replaced. Javascript is a totally different animal.

4. Security. When using a browser your access to the local disk is highly limited whereas you will take the same for granted in windows application. If there is any code in the windows app that requires local resources, then that is going to be a trouble spot for you.

I would recommend the following:

• Verify if your current application has any local disk access requirements (e.g. read/write to local file etc).
• As you write the different http modules or handlers, you can try leveraging some of the backend/ business logic part of the existing windows application.
• Give some thought to what part of your application can become a web service.

Answer 2

It sounds like the application needs a lot of refactoring to clean it up. If you want to move to a web model, and have maximum reuse you will really need to do that. Before you move to a web model I think you need to understand if it will be possible to replicate your user interface in that model. Is it your unique selling point from a customer perspective? You want decisions like this to be user driven rather than purely technical decisions.

It sounds like your application is the perfect candidate for a thick client application, rather than the lowest common denominator web model.

Some things to consider:

• How will the web interface impact the Tablet interaction?
• What new customers will having a web version bring you?
• Will existing customers abandon your product?
• Do you have access to consultants or outside resource with the right skills to mentor you in web technology? If you don't you can rely on StackOverflow or other web resources to help. You need some good mentoring and guidance on the ground with you.
• What happens if you start this effort and it takes much longer than you expect? You know the app but don't sound like you know the web. Past experience shows that massive rewrites like this can end in disaster (it never sounds so difficult at the start)
• Can you possibly write new features in a web-based version?
• Could you move to ClickOnce deployment to make the application easier to deploy to customers. One of the benefits of the web is easier (zero) deployment. Can you get closer to that?
• Would it be easier to migrate to WPF and create a browser application with that?
• Silverlight or Flex might be better options for creating a rich experience, and may be more approachable for WinForms developers. Is this a possibility?

Answer 3

It seems like your app. is one of those that works best as a desktop app. Though you want your users to be able to access your app. using a browser.

I would suggest refactoring as much as possible so that the GUI gets cleaner and don't have "code". When you've done this, start developing a asp.net mvc app but keep your desktop app. You should be able to use all layers except the UI layer, making it easier/faster/... Now that mvc exists, I'd say webforms is more about letting non-web devs do web. But you know web, sort of, and you want control so mvc is the way to go.