The architecture needs to be built up in layers in data storage, data access, application services, and the application. This is depicted in the following screenshot:
Each layer can be designated as a group of analogous logical tasks, as the data storage layer acts as a data source, such as a relational database, a filesystem, or any other data source. The data access layer communicates with the data source to get or store data from the storage layer, and provides a nice abstraction in the data source to be delivered to the service layer. The service layer is a medium of data persistence with the application layer, and also offers other services, such as a validation service. The data access objects reside in the data access layer, and the business objects reside in the service layer. Finally, the applications reside in the application layer, which directly deals with end users. So, the service layer could be the surface tier for our...