The implementation of BaseDataObject provides mechanisms for all of the common data access needs we identified earlier (all the CRUD operations):

• It allows derived data objects, once they've been instantiated, to create and update their state data
• It provides a single mechanism that allows one or more data objects to be read from the data store, and as a bonus allows for some degree of object retrieval based on criteria other than just the oid of the data objects in question
• It provides a single mechanism for the deletion of object data

The actual implementation of those methods is the responsibility of the data objects themselves, which will relate directly to the storage mechanism that each object type uses.

The data storage for the Artisan Application, reading and writing data to local files on the user's machine, is, in many respects, the simpler of the two data storage options to implement, so we'll start with that.