Constructing Dependency Research Of Object-Oriented System Based On UML

Dependency is extensively used in object-oriented system. The researches of dependency have been being paid close attention to by software engineering. Though a lot of achievements, which mainly based on theory, have been obtained, many problems remain unsolved for their complex nature..On the basis of investigation on the related literature of dependency at home and abroad, primarily according to class, this paper puts emphasis on studying the reason and mechanism that causing dependency, formal definition, subdivision and measurement of dependency by combining mainstream modeling UML..The main works and conclusion in this paper are as follows:(l)According to elementary feature of object-oriented system, this paper analyses the basic reason and mechanism to cause dependency. The reason is encapsulation, inheritance and polymorphism, and the mechanism is function dependency, inheritance, global variable, using API, client/server, message and class defining instance variable.(2) According to the feature of class, this paper defines strict class dependency and fractionates dependency into data dependency and method dependency, and proves strict and describes the two concepts. This subdivision describes virtually the class dependency carefully, then show characters of class dependency: neither reflexive nor non-reflexive, neither symmetric nor non-symmetric, and non-transitive.(3)The class dependency has been measure in reason from two classes to several classes, and provided these terms: depending metrics, depended metrics, absolute depending metrics, depended metrics, relative depending metrics and relative depended metrics, then affirming class size.(4) Combing research conclusion with class diagram of UML, transforming class diagram into direct dependence graph, constructing class testing dependence aggregate, then reducing regression testing instance. The algorithmic time and space complexity are O (n2 ) .(5) Combing package of UML, the research of dependency extent class to subsystem.