Functional and Structural Modeling - Coursework Example

Introduction Functional modeling generally deals with the activity of developing models of devices, objects and processes of a system based on their functionalities. It is basically concerned with representing knowledge about functions which forms a basis for solving problems related to system representation. It shows how general system goals are achieved through the realization of the sub goals via the system sub functions. According to Tauber, functional model represents a part of the designer’s intention, the design rationale. (pg 12). Structural modeling on the other hand entails data structure description, that is, it describes the structure of data that is supports the business processes of an organization.

There are different ways of representing the structure of data used in a system including class diagrams, object diagrams and CRD cards. Structural modeling Structural modeling in system analysis and design is useful in various ways but the main purpose of structural models is to represent ideas, things and important concepts in the application domain. In addition, structural models are used to create a vocabulary for analysts and users. According to Wixom, It is also used in order to reduce the schematic gap between the real world and the software world ( chpt 7 pg 6) Classes, attributes, relationships and operations constitutes the four major components of structural modeling.

Classes are templates for creating objects or instances and can either be concrete or abstract. Classes’ example may include user interface data structure and application domain. Class diagrams are used in structural modeling to represent classes, show their attributes, operations and their relationships. Attributes on the other hand are used to describe classes and only important and relevant attributes to the task are included in the structural modeling. An attribute can be public, private or protected depending on its visibility type.

Objects or instances can take actions known as operations while relationships show how classes are associated. Operations can be broadly grouped into update (changes value of attributes), query (makes information about state available) and constructor which create an object. Functional modeling Functional modeling include various design element such modules, processes inputs and outputs, interfaces and design of databases and files. A fully functional system is made up of a collection of small independent subsystems called modules.

The modules are coded and designed separately after which they are brought together to form a complete and fully functional system. Shared use and size are some of the factors to be considered while coding a designing a module. Limiting the number of instructions in a module ensures a small size module which recommended compared to a large module. Duplication of functions in modules should be avoided by creating a single module which can be called by other modules in case of need. System functions consist of processes which are specific acts with definable beginning and ending points beside inputs and outputs.

Processes may be distinct but share certain common properties such as: processes identify what is done and not how, they posses definable starting and ending points, processes are carried out irrespective of organizational structure. Interface is an important part of any computerized system since it provides the platform for the user to interact