Meta Data Services Programming
Understanding Application Data
You can begin planning your information model by answering these questions:
- What kinds of objects will the tool store? That is, what are the classes to which the tool's objects must conform?
- What kinds of relationships will the tool store? That is, what are the relationship types that describe how objects can be related?
- What properties apply to the objects of each class or the relationships of each relationship type?
You can think of any application structure as objects, properties, and relationships. When you store data about your tool or application in a repository, you can create objects, indicate how those objects are related to each other, and define properties for each of those objects or relationships. To create the hypothetical bookseller's tool, you can do the following:
- Create objects such as:
- Book, to store instance data like Moby Dick (a book) and Inside OLE (a book)
- Publisher, to store instance data like Microsoft Press® (a publisher)
- Person, to store instance data like Kraig Brockschmidt (a person) or Herman Melville (a person)
- Book, to store instance data like Moby Dick (a book) and Inside OLE (a book)
- Indicate how those objects are related:
- Herman Melville (a person) wrote Moby Dick (a book). Kraig Brockschmidt (a person) wrote Inside OLE (a book). These relationships are the same and can be described as Authorship.
- Microsoft Press (a publisher) published Inside OLE (a book). This relationship can be described as Publication.
- Herman Melville (a person) wrote Moby Dick (a book). Kraig Brockschmidt (a person) wrote Inside OLE (a book). These relationships are the same and can be described as Authorship.
- Decide which properties you need to capture additional information for each object:
- Birthday is a property that can describe a person. (The birthday of Herman Melville is November 12, 1819.)
- Address is a property that can describe a publisher. (The address of Microsoft Press is One Microsoft Way.)
- Birthday is a property that can describe a person. (The birthday of Herman Melville is November 12, 1819.)
- You can also decide which properties you need for relationships:
- Year of Publication is a property that can describe the Publication relationship. (The year of publication for Inside OLE is 1995.)
The following figure summarizes this data. The figure shows typical data about specific books, authors, and publishers. Because the data is typical, it helps you visualize the kinds of data that your model must accommodate.
