| | An applicative document is an instance of a class inheriting CDM_Document.
These documents have the following properties:
- they can have references to other documents.
- the modifications of a document are propagated to the referencing
documents.
- a document can be stored in different formats, with or
without a persistent model.
- the drivers for storing and retrieving documents are
plugged in when necessary.
- a document has a modification counter. This counter is
incremented when the document is modified. When a document
is stored, the current counter value is memorized as the
last storage version of the document. A document is
considered to be modified when the counter value is
different from the storage version. Once the document is
saved the storage version and the counter value are
identical. The document is now not considered to be
modified.
- a reference is a link between two documents. A reference has two
components: the "From Document" and the "To Document". When
a reference is created, an identifier of the reference is generated.
This identifier is unique in the scope of the From Document and
is conserved during storage and retrieval. This means that the
referenced document will be always accessible through this
identifier.
- a reference memorizes the counter value of the To Document when
the reference is created. The From Document is considered to
be up to date relative to the To Document when the
reference counter value is equal to the To Document counter value.
- retrieval of a document having references does not imply
the retrieving of the referenced documents.
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1.6.3