System Analysis and System Requirements
Object Modeling, Process Modeling, and Strategies for System Analysis and Problem Solving
April 6, 2005
A class can be described as a collection of objects of similar type. These objects often share the same attributes, operations, methods, relationships, and semantics. Additionally, once a class is defined any number of objects can be created and associated to that class. For example, beagles and boxers represent different breeds (i.e. instances) of "dogs" which also can be viewed as a distinct class. Furthermore, defining classes, as part of the object modeling process is not that different from the traditional system analysis process, which seeks to achieve a goal (i.e. object modeling seeks to understand a solution; whereas, system analysis which seeks to understand a problem).
Attributes are data fields that represent some property of the containing object that is shared by all instances of the object's class. Attributes normally have names (e.g., "Address") and Types (e.g., "String" or "Boolean"). An example of this would be the "Address" of a "User." In addition, attributes define the characteristics of the class that, collectively, capture all the information about the class.
Encapsulation represents packaging several items together into one unit. In addition the application of encapsulation involves keeping the external representation of an entities properties and methods independent of its actual implemented use. Encapsulation therefore, allows an entity to be leverage by other parts of an application without the fear of changes in the implementation use causing a snowball effect.
Logical Process modeling is a technique for organizing and documenting the structure and flow of data through a system's processes and/or the logic, policies, and procedures to be implemented by a system's processes. In addition, to organizing the flow of data throughout a system, logical models also provide means of bridging the gap of communicating information to end-users in a non-technical manner while also preserving the requirements. Finally, logical models encourage creativity and reduce the risk of missing requirements, which are normally missed because of pre-occupation with technical details.
Like the logical processing model a context data flow diagram defines the scope and boundary for the system and project. Because the scope of any project is always subject to change; the context diagram is also subject to constant change. A context diagram is referred to as being another representation an environmental model. Finally, the initial project scope can be defined using a context diagram. A project's scope is important in that it defines what aspect of the business a system or application is supposed to support.
An event diagram represents the final area of my discussion of the Process Modeling method. An event diagram represents a context diagram that...