Primary knowledge Object-oriented (iii)

The research of object-oriented development method has become more and more mature, and many object-oriented products have appeared in the world. The object-oriented development method has Coad method, Booch method and OMT method, etc.

1. Booch method

Booch first described the basic problem of object-oriented software development method, pointed out that object-oriented development is a fundamentally different from the traditional function decomposition design method, object-oriented software decomposition is closer to people's understanding of objective things, and functional decomposition only through the transformation of the problem space to obtain.

1. Coad method

The Coad method is the object-oriented development method proposed by Coad and Yourdon in 1989. The main advantage of this method is that through the combination of the experience of large system development and the object-oriented concept in the past years, a set of systematic principles are put forward in the cognizance of object, structure, attribute and operation. This method completes the identification of class and class hierarchy from the point of view of requirement. Although the Coad method does not introduce the terms of class and class hierarchies, it has in fact embodied the characteristics of class and class hierarchies in concepts such as classification structure, attributes, operations, and message associations.

1. Omt method

The OMT method was introduced in 1991 by 5 people such as James Rumbaugh, whose classic works are "object-oriented modeling and design". This approach is a new approach to object-oriented development, which is based on modeling real-world objects, and then using analytic models around these objects for language-independent design, object-oriented modeling and design facilitates understanding of requirements and facilitates the development of a clearer and easier-to-maintain software system. This method provides a practical and efficient guarantee for software development in most application fields, and strives to find a practical method for solving problems.

1. UML (Unified Modeling Language) language

The Software Development engineering field has made unprecedented progress in the 1995 ~1997, and its achievements exceed the sum of the achievements of the Software engineering field over the past 15 years, one of the most important results is the emergence of the same modeling language (UML). UML will be the dominant standard modeling language in the field of object-oriented technology.

UML not only unifies the Booch method, the OMT method, the Oose method the expression method, but also has made the further development, finally unifies for the populace to accept the standard modelling language. UML is a well-defined, easy-to-express, powerful and universally applicable modeling language. It incorporates new ideas, new methods and new technologies in the field of software engineering. Its scope is not limited to support object-oriented analysis and design, but also supports the whole process of software development starting from requirement analysis.

Under the object-oriented object model, the object model represents the static and structured system data nature, describes the static structure of the system, it is described from the object relation angle of objective world entity, and shows the relation of object. The model mainly concerns the structure, properties and operation of the objects in the system, which is the core of the three models in the analysis stage and the framework of the other two models. Object modeling is designed to describe objects. By abstracting the object into a class, we can abstract the problem and add the generalization ability of the model. An action is a function or transformation used by an object in a class, and each object in a class can share an operation, and each operation has a target object as its implied argument. The Association of objects is a means of establishing relationships between classes, while chains are a means of establishing relationships between objects. Chains represent physical and conceptual junctions between objects, associations represent a relationship between classes, a chain is an instance of an association, and an association is an abstraction of a chain. Role description The role of the class in the association, which is at the associated endpoint. A restricted association consists of two classes and a qualifier, which is a specific attribute used to effectively reduce the number of associated re-numbers, and the qualifier is described in the associated terminal object set. The limitation improves the accuracy of semantics and enhances the ability of querying, and in the real world, there are often qualifiers. The multiplicity of associations refers to how many objects in a class are related to an object of the associated class.

The object model is made up of one or more templates. The template divides the model into manageable sub-blocks, which provide an integrated intermediate unit between the entire object model and the class and the associated building blocks, and the class name and the close joint in the template are unique.

Primary knowledge Object-oriented (iii)