You use Data Dictionary classes by creating a set of Data Dictionary Objects. These objects must be properly connected and placed within an appropriate component object such as a view, web-object or business process object. This DDO object structure will handle all database processing for that component.
An application will contain many of these components; each one containing its own encapsulated set of DDOs.
Before you can use a DDO structure you must understand how to build them. This section provides that information.
Before you can build a DDO structure, you must first create the Data Dictionary class.
After you have built your DDO structure, you use them by creating DEOs and methods
A Data Dictionary object structure has a limited set of operations that it needs to perform. A DDO should be able to:
Find records - while properly finding all appropriate parent and child records
Clear records - while properly clearing or not clearing all appropriate parent and child records
Save records – while properly validating and saving all appropriate parent records. A save must properly save records in a multi-user environment and be able to properly roll back a transaction if a save fails.
Delete records – while properly validating that a delete is appropriate and allowed.
Any of these operations must operate under full control of all Data Dictionaries that participate in the operation. At all times, all the rules of DDOs must be obeyed. These rules ensure that only valid data is saved; that relational balances are properly maintained; that record IDs are properly assigned; that key field values are properly maintained; that the relationship between DDOs are always properly maintained, and more.
These rules are defined within the Studio’s Data Dictionary Modeler when you are creating and modifying your Data Dictionary classes. When you are building your Views, Reports, Web-Objects, etc. you should not be worrying about these Data Dictionary rules. You just want to know what messages are needed to perform the operation. If the operation is invalid, you expect that the Data Dictionary class will protect you.
Propagation of DDO Operations
Diamond Structures in DDOs
DDOs and Extended Field Support
Local DD Relationships