Chapter 12 Creating Mappings

Introduction to Model Object Mapping

Object mapping allows you to establish connections between objects belonging to heterogeneous models and diagrams. You create mappings between objects to setup a structure for data movement and transformation or simply to express a simple correspondence between model objects. When data movement is involved, data originates in a data source and is loaded to another target database or model.

You can create mappings in either of the following ways:

From the Mapping Editor that gives you a global view of all the mappings to objects in the current (target) model.
From the Mapping tab in the property sheet of model objects, when you are working on a specific object.

The following table lists the supported types of model-to-model mapping in PowerDesigner:

Source	Target	Mapping type
PDM	OOM	O/R (Object-Relational) – to associate classes to tables to store OOM objects into a relational database.
CDM	OOM	O/CDM (Object-Conceptual) – to associate classes and associations to CDM entities and associations or relationships.
OOM	OOM	O/O (Object-Object) – to associate classes and attributes from one OOM to another.
PDM	PDM	R/R (Relational-Relational) – to associate tables and views to other tables of another database.
		Multidimensional-Relational – to associate cubes, facts and dimensions to tables to populate OLAP cubes from relational databases.
PDM	XSM	XML/R (XML-Relational) – to associate elements and complex types to PDM tables, views and abstract data types.
OOM	XSM	XML/O (XML-Object) – to associate elements and complex types to OOM classes.
XSM	XSM	XML/XML (XML-XML) – to associate elements and complex types from one XML Model to another in order to define how an XML document can be transformed into another (usually, using XSLT or Xquery).
CDM	CDM	CDM/CDM (Conceptual-Conceptual) – to associate entities, associations, inheritances and data items from one CDM to another.
OOM	CDM	CDM/O (Conceptual-Object) – to associate entities and associations to OOM classes and associations to clarify object relationships.
LDM	LDM	LDM/LDM (Logical-Logical) to associate entities, relationships, and inheritances from one LDM to another.

Each mapping is recorded in a query, a textual expression or an XPATH expression defined in the target object, which permits the selection of data from the data source and its transfer to the target model. In certain cases, you can further define the mapping by associating sub-objects in the target and source models.

Objects that can be mapped

The following table lists the objects and sub-objects that can be mapped for each type of model:

Model	Objects	Sub-objects
PDM	Table	Table column
	View	View column
	Dimension	Attribute
	Fact	Measure
	Cube	Measure
	Reference	N/A
OOM	Class	Class attribute, operation, association
XSM	Element	Element attribute
	Complex type	Complex type attribute
CDM	Entity	Entity attribute
	Association/relationship	Association attribute
	Inheritance	Inheritance attribute
	Data item	N/A
LDM	Entity	Entity attribute
	Relationship	N/A
	Inheritance	Inheritance attribute

Accessing inter-model mappings in the ILM

The Information Liquidity Model (ILM) provides a graphical view of various databases (PDM) and formats, such as XML document (XSM), data application (OOM), and conceptual data (CDM) together with the different transformations that operate between them. You can easily visualize or further define the correspondence between the various elements by right-clicking the data access link between these elements and opening the Mapping Editor:

For more information, see the "Data Access Links" section in the "Building Information Liquidity Diagrams" chapter in the Information Liquidity Modeling guide.

Creating replications

The Mapping Editor also allows you to visualize and manage replications defined for RepServer and Mobilink in the ILM. It is available from the replication process contextual menu:

This ILM Mapping Editor is slightly different to the standard Mapping Editor:

For more information, see the "Using the Mapping Editor for Replications" chapter in the Information Liquidity Modeling guide.