What should this specific service class look like in my domain?

Question

I'm coming from a WebForms world where all logic is located in the codebehind of the aspx-pages. After reading a few books on ASP.NET MVC, listening to some podcast and watching some videos on Tekpub, I've decided that it is time to approach things a bit differently.

Unfortunately, I'm already stuck.

I'm trying to build some sort of small and basic CMS in which I can add multiple websites.

I know I should keep my controllers thin, so I guess I should use some sort of service class (let's call it WebsiteService) to do this. I'm using Entity Framework for data access and my Views all use specific ViewModels. When I Create or Edit a Website, these four things should happen:

• Validate the input
• Add information about the Website to the database (Update information if it's an Edit)
• Create a directory on disk (Possibly rename the directory if it's an Edit)
• Add a host header to an IIS Website (Possible remove the old host header and a new one if it's an Edit)

Basically, I guess the WebsiteService should perform more advanced validation, write to the database, create/edit a directory, add/remove host headers and return something to the controller to indicate if it succeeded or not.

What should this class look like? I have a few questions to which I don't know the answer.

1. Should the WebsiteService also translate the CreateWebsite ViewModel to the actual Website class or should something else do this so that the WebsiteService accepts an actual Website object?
2. Basic input validation is done by using Validation attributes on the ViewModel. More extensive validation ("Is there already a Website with this domain name in the database?") should also be done. Should the WebsiteService do this as well?
3. Should all 3 steps (save to database, create directory, add host header to IIS) be done in one public method (WebsiteService.SaveWebsite(ViewModels.CreateWebsite website)) or should I provide separate methods which the controller has to call? (I guess not because I suppose the call order is important.)

Answer 1

The answers to this is partially subjective, matter of opinion, but here are my thoughts:

1. It could. But a better approach would be to use AutoMapper to do this for you. One of the "must have" open source tools for data-driven MVC applications.

2. Yes - input validation should be done via validation attributes on the View Models. More extensive/domain/business validation can either be done in the service, or on the domain models themselves. I prefer (and use) the second option. My domain models are also my POCO's (used by EF), but i have extra methods/properties specific to the domain (but not the database).

3. No, i think this should be in seperate methods, mainly for testability/seperation of concerns. You've got three things going on - database persistence, file writing and IIS work. That to me should be three different services. I would have your "WebsiteService" delegate these tasks to other services.