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Mapping Object Models to SDL


When moving from an analysis view of an application to a design of the application, one of the major tasks is to define the relation between analysis concepts and design concepts. There are two different ways to view this: either the design is seen as an elaboration and refinement of the analysis model or the design can be seen as a transformation of the analysis model. In practice both viewpoints are useful. When creating the design a transformation is performed from the object model developed in the analysis activity to the SDL design models. The concepts in the object model are mapped to suitable concepts in the SDL domain. However, when this mapping has been done the analysis model is used as an abstract view of the application where only the details relevant from an analysis perspective is present and the design is viewed as an elaboration and refinement of the analysis model.

When mapping object models to SDL there are several aspects to cover:

The structure of an object model of interest for the mapping to SDL are of two kinds:

The aggregation structure in the object model is in general in SDL represented by the block hierarchy as described in Architecture Definition. The actual mapping between the object model and SDL involves creating the block structure based on the aggregation structure and is further discussed in Mapping Aggregations of Active Objects.

The module structure of the analysis model is one of the inputs to the definition of the design module structure. In SDL the major code structuring concept is the package and in general it is recommended to keep a simple mapping from the module structure of the analysis model to the packages in the SDL design. This is further discussed in Design Module Structure.

In SDL the interfaces of processes, blocks etc. are separated from the description of behavior or implementation of the block/process. This implies that in general there are two different mappings from classes in the object model to SDL, one to the interface definition and one to the process/block definition. Interfaces in SDL are defined using signals or remote procedure calls as described in Static Interface Definitions Using SDL and the mapping to these concepts is outlined in Mapping Object Models to SDL Interface Definitions.

The mapping of the classes in the object model to the corresponding SDL behavior definition is an issue of object design and is depending on if the object is an active or passive object. Active objects are mapped to SDL processes (or process types) and passive objects to data types. These different mappings are discussed in Mapping Object Models to SDL Design Models.


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