Architecture design help

Question

I'm looking for some input on my current project architecture. There are three components: Server, Desktop, and Mobile Device.

I have 2 goals:

1) Send data (Approx. no more than 100 KB of text) from the Desktop (multi platform client application running on windows XP/Vista/7, and Mac OS X) to a server (Windows Server 2008, IIS 7, WCF RESTful service) to save in a database (Sql Server). The services need to be scalable because the number of desktop devices and frequency they send data is unknown.

2) A service to retrieve data from the database (Sql Server) and send to a mobile device(Iphone and Android application. Message size no more than 100 KB of text). Service needs to be scalable because number of mobile devices and frequency they connect is unknown.

My proposed solution:

Server Side (Sql Server and Windows Server 2008): I'm looking at a WCF RESTful JSON services to communicate with Desktop App(s) and Mobile App(s). I like WCF because I am most proficient in C#, have some experience implementing WCF, after doing some research it appears all technologies used for the platforms(Windows XP/Vista/7 and Mac OS X) can easily communicate with the WCF RESTful service.

• Any high level fundamental issues with the WCF service in this scenario?
• I have only implemented WCF on a Windows Server 2003 machine with ~800 devices connecting every 15 minutes. The server was a physical in house server running on a private network. I need this solution to be hosted and scalable. Any recommendations for hosting a Windows Server 2008? Is there a better technology to host the service? (I'm not very familiar with how the cloud stuff works)

The services will be saving and retrieving data from a SQL server. I would like to use LINQ to SQL as my data access layer. It's my understanding there are large licensing fees tied to SQL server so I may need to go with SQL Server Express for now.

• I'd prefer to keep the WCF services and database hosted separately (2 diff machines). Any recommendations for hosting sql server(or express)? Is there a hosting service that can scale better for my database? Does it make sense to keep these on 2 diff machines?

Desktop (Client Side) I am required to develop for Windows XP/Vista/7 and Mac OS X. I plan to write a .net application to run on the windows machine(s). I"m still up in the air if i'm going to write (and learn :P) XCode or try mono. Any cross-platform ideas?

• Should I expect to have any fundamental problems getting the desktop applications to talk to my WCF RESTful services?

Mobile Applicaitons I am required to developer for the IPhone and Android. There are many examples of making WCF RESTful service calls using Objective C and the Android SDK. I'm considering trying a cross platform (ie. Appcelerator). From a high level it appears these mobile cross platforms have built a Java script layer that works with both IPhone and Android!

• Any thoughts on using the cross platform technology to write ONE mobile app to run on IPhone and Android?

• Any fundamental issues calling the WCF RESTful service in javascript?

Sorry for the somewhat long post. I have never designed a solution of this size. All feedback is appreciated.

Thank you!

Answer 1

As you are clearly wanting to use Microsoft technologies - the suggestions about Mono probably make sense to you and will certainly make things easier.

However I think you may find that you compromise elements of the user experience for Mac and iPhone users which is not ideal as these users tend to have the highest expectations for great user experiences.

I understand that we don't live in an ideal world but if we did you would develop a separate client for each platform - optimised to the needs of each platform. Unless you application is doing a lot of data manipulation the data layer is now abstracted to the server viw your JSON interface so you will not gain much from sharing the data objects across implementations.

As it seems you are implementing the project in a small team (yourself?) then I would suggest that you look at implementing a web solution with the HTML javascript communicating with the server over JSON.

The other option is that you use a flex/air client on windows and mac and flash on the android and Adobe's solution to compile flex/air into iPhone code.

Good luck though.