Part-whole relationship categories and their application in object-oriented analysis

Abstract

and, conversely, the construction of composite objects out of individual parts have long been recognized as ubiquitous and essential mechanisms involving abstraction. This applies, in particular, in areas such a s CAD, manufacturing, software development, and computer graphics. Although the part-of relationship is distinguished in object-oriented modeling techniques, it ranks far behind the concept of generalization/specialization and a rigorous de nition of its semantics is still missing. In this paper we rst show i n w h i c h w ays a shift in emphasis on the part-of relationship leads to analysis and design models that are easier to understand and to maintain. We then investigate the properties of part-of relationships in order to de ne their semantics. This is achieved by means of a categorization of part-of relationships and by associating semantic constraints with individual categories. We further suggest a precise and, compared with existing techniques, less redundant speci cation of constraints accompanying part-of categories based on the degree of exclusiveness and dependence of parts on composite objects. Although the approach appears generally applicable, the object-oriented Uni ed Modeling Language (UML) is used to present our ndings. Several examples demonstrate the applicability of the categories introduced. Index terms: Conceptual modeling, object-oriented analysis, object-oriented design, part-of relationship, part-of relationship categories, partonomy, aggregation, semantic constraints, object lifecycle. OO-terms categories of characterization, method used part-of relationship comment, example Booch has-relationship by-value aggregation part p is a part of the state of whole w, aggregation by-reference aggregation attributes are considered parts OMT part-of-relationship not distingusished attributes are not considered parts, operation aggregation propagation to be considered Jacobson consists-of relationship not distinguished an aggregate is composed of other objects, its parts composition partonomies are considered Martin/ composed-of relationship mutable composition composition is the act or result of forming Odell composition immutable composition an object from its component p a r t s Embley part-of-relationship part-of distinguished attributes are considered parts, e.g., aggregation from member-of Ordernumber part-of Order but: Student m e m ber-of StudentClub UML whole-part relationship by-value aggregation composition indicates that the lifetime of the parts version 0.9 aggregation or composition is dependent on the lifetime of the whole and 1.0 by-reference aggregation by-value aggregation is semantically equivalent t o an attribute properties: transitivity, a n tisymmetry

Advanced query language for manipulating complex entities

“…Järvelin and Niemi (1995; Object-orientation has concentrated on modeling and manipulating the is-a relationship rather than complex entities (complex objects in the object-oriented terminology) (Renguo et al, 2000). One indication on this is that the support of object-oriented programming for complex entities, similar to the support for the is-a relationship, is desired (Motschnig-Pitrik & Kaasböll, 1999). Likewise, the indexing mechanisms of object-oriented databases mainly support the manipulation of the is-a and the association relationships.…”

“…It is important to specify all constraints, which complex entities must satisfy. Civello (1993) discusses constraints for their representation (see also Halper et al, 1998;Motschnig-Pitrik & Kaasböll, 1999). Likewise the object-oriented modeling methods OMT (Rumbaugh et al, 1991) and UML do not deal with the inheritance of properties in complex objects.…”

“…Many authors (e.g. Winston et al, 1987;Kim et al, 1987;Civello, 1993;Motschnig-Pitrik & Kaasböll, 1999;Halper et al, 1998;Barbier et al, 2000) have focused on the semantics of complex entities and on categorizing them. For us, the most important semantic distinction is whether a complex entity is exclusive or shared.…”

“…Motschnig-Pitrik & Kaasböll, 1999;Renguo et al, 2000). They can neither be represented through ordinary attributes because the distinction between a property and a component is lost in this case (Civello, 1993;Artale et al, 1996).…”

A Conceptual Model for Remote Data Acquisition Systems

“…ParWhole relationships are commonly used to model the construction of composite objects out of individual parts. Part-Whole relationship categories and their application in object-oriented analysis are further discussed by Motchnig-Pitrik et al in [20]. We used the "Composite" pattern, detailed in [21], to compose objects into tree structures to represent part-whole hierarchies.…”