Chapter 3 Building Information Liquidity Diagrams
A data access link is a relationship that documents the way data are mapped between two of the following data stores:
You can perform the following mapping types in PowerDesigner. The target model owns the mapping:
| Mapping type | Source > Target |
|---|---|
| O/R (Object-Relational) | PDM > OOM |
| O/C (Object-Conceptual) | CDM > OOM |
| R/R (Relational-Relational) | PDM > PDM |
| XML/R (XML- Relational) | PDM > XSM |
| XML/O (XML-Object) | OOM > XSM |
| XML/XML (XML-XML) | XSM > XSM |
| C/O (Conceptual-Object) | OOM > CDM |
| C/C (Conceptual- Conceptual) | CDM > CDM |
The data access link graphically materializes a mapping between two data stores.
From the contextual menu of the data access link, you can access the Mapping Editor, in order to visualize or further define the mapping between the source and target models associated with each one of the data stores. When several models are associated with a given data store, a dialog box is displayed that allows you to select a model from the list. The corresponding data source with its associated model is automatically created in the Source pane of the Mapping Editor.
You can also access the Mapping Editor, from the contextual menu of the source or target data store of a data access link.
Besides, you can recover the ILM diagram corresponding to the mapping between two models thanks to the created data sources in the Mapping Editor. To do so, you use the Complete Data Access Link command or the Complete All Data Access Links (for recursive completeness) command in the contextual menu of a data store (database, XML document, data access application or conceptual data) having an associated model.
For more information about mappings, see the "The Mapping Editor" chapter in the General Features Guide .
The orientation of the data access link is defined by the way it is created graphically and determines the Access Type property of the data access link.
The following schema illustrates a data access link coming from a database (PDM) indicating that the data contained in the database, is read only (extracted) by the data access application (OOM):
The following schema illustrates a data access link coming from the data access application (OOM) indicating that the data access application writes only (consolidates) the data in the database (PDM):
If you select Read/Write in the Access Type list of the data access link property sheet, it means the data access application (OOM) extracts and consolidates data in the database. The access link looks as follows:
Dragging a data access link to a different object
You change the objects at either end of a data access link by clicking the data access link to select it, and dragging one of the attach points to a different object.
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