Advanced property handles

The intention and extension managed by a property handle is defined in terms of access paths in many cases. An access path is a kind of query statement (like SQL queries for relational databases). In fact, an database queries are only one possibility of defining an access path.

Simple property handles are based on property references, i.e. simple property or extent names, which are specific access paths as well. Besides, ODABA provides advanced property handles for different purposes, which can be constructed by means of more complex access paths. Similar to basic property handles, advanced property handles are used to manage collections, instances or elementary values, except, that those need not to refer to persistent data.

• Other advanced property handles, which are not based on access paths, can be created in order to manage temporary or transient collections (transient properties) created by the application or defined in the data model.

In may cases, advanced properties just provide a sort of short cut for accessing data (property path and path property). Other access paths allow defining complex operations on data (views) or managing transient result instances or collections.

The functionality for advanced property handles is the same as for basic property handles. The essential difference is the data (collection) managed by the property handle.