System Analysis and Design - Object and Process Modeling, and Stragies for System Analysis and Problem Solving

System Analysis and System Requirements

Object Modeling, Process Modeling, and Strategies for System Analysis and Problem Solving

April 6, 2005

Object Modeling

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.

Process Modeling

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 focuses on the inputs, outputs, and data store interactions for a single event. In addition, most event diagrams are also representative of a single process, which can be referenced back to the event identified for a decomposition diagram. Event diagrams therefore are valuable for identifying and addressing event driven factors, which when combined with other event diagrams (i.e. events) can contribute to an increase in problems and issues associated with a projects goals.

Strategies for System Analysis and Problem Solving

Modern Structure Analysis derives its origins from System Analysis and Structured Design (SASD) developed in 1970's to ease the management tasks involved in software development. System Analysis and Structured Design (SASD) introduced the principle of dividing the system into smaller pieces and understanding what each component does along with the relationship between these components. In 1989 Edward Yourdon introduced a modern version of the SASD that he and two other colleagues introduced in response to the emergence of structured programming in the late 70's. The Modern SASD approach continues to leverage the classical method, which is represented by the Environmental and Behavioral Models. The Environmental Model is defined by the relationships which exist between the system and the outside world; whereas, the Behavioral Model manages the internal mechanics and behaviors of the system. Modern SASD introduces the Implementation Model to address post customer analysis and approval of system requirements. The Implementation Model represents