System Models

Introduction to System Models

Models are necessary to better understand the project. They represent the information that software transform, the functions that enable this transformation, the features that users desire, and the system’s behaviour as the transformation is taking place. There are various system models like analysis model, system model, context model, behavioural model, data model and object model.

Various System Models

Given below are the various system models:

1. Analysis Model

The analysis model represents the user requirements by depicting the software in three different domains: information domain, functional domain, and behavioural domain. This model is multidimensional. If any deficiency remains in the analysis model, then the errors will be found in the ultimate product to be built. The design modelling phase depends on the analysis model. The Analysis model uses diagrammatic form and text to describe the requirement of data, functions and behaviour of the software to be built.

Mostly it is designed by a software engineer, or system analyst or modeller or project manager. This model describes the problem from the user’s end. The essence of the problem is described without any consideration of how a solution will be implemented, and implementation details indicate how the essence will be implemented.

2. Design Model

Design Model provides variety and different views of the system just like architecture plan for House. Different methods like data-driven, pattern-driven or object-oriented methods are used for constructing the design model. And all these methods use a set of design principles for designing a model. Design must be traceable to the analysis model. User interfaces should consider the user first. Always consider the architecture of the system to be built. Focus on the design of data. Component level design should exhibit functional independence. Both user and internal must be designed. Components should be loosely coupled.

3. Context Model

The context model is used to specify the boundaries of a system. It represents the system as a whole. When we want to design a context model, we should know the answer and what process make up a system? Social and organizational issues may affect the decision on where to position the system boundaries. This model shows the system and its relationship with other systems.

4. Behavioural Model

Behavioural Model describe the overall behaviour of the system. To represent system behaviour, two models use one is Data processing model, i.e. DFD (Data Flow Model), and another is state machine model, i.e. state diagram.

Data Flow Diagram:

It is used to model the system data processing, also known as a functional model, as it is a graphical representation of an enterprise function within a defined scope. It shows end to end processing of data. It takes an input – process – output view of the system. It can be easily converted into software as they just represent the flow of data objects. This diagram enables a software engineer to develop a model of the information domain and Functional domain at the same time. The data processing model is the core modelling activity in structured analysis.

5. State Machine Model

The state is the mode or condition of being. A state diagram is a dynamic model that shows changes of state that an object goes through during its lifetime in response to an event. It is used to help the developer better understand any complex functionality of specialized areas of the system. It depicts the dynamic behaviour of the system in response to an external and internal event. Likewise, it uses various notation to show the function such as initial state, final state, state, transition, event, action, history site, signal, the action inside the state, self-transition.

6. Data Model

Analysis modelling starts with data modelling. Software Engineer defines all data objects which are required for the system. It is used to describe the logical structure of the data processed by the system. ER (Entity Relation Attribute Model) is one type of data model that illustrates the entities in the system, their attributes and relationships between entities. Elements of data modelling help to provide appropriate information to understand the problem.

This data modelling concept is called as cardinality. ER diagram consists of information required for each entity or data objects as well as it shows the relation between object also. IT shows the structure of the data in terms of the tables. There are three types of relations that exist between these objects – one to one relation, one to many relations and many-to-many relation.

7. Object Model

Object model consists of former properties and procedures and methods which tell us how to access these properties. The goal of class modelling is to describe the object. An object is a concept, abstraction or thing which identifies that has meaning for an application. The object model shows individual objects and the relation between them. It is helpful for documenting test cases and discussing examples. It is very useful to understand uncovered rules definition of resources and their relationship. Object diagrams are valuable because they support the investigation of requirements by modelling the examples from the problem domain.

This is a guide to System Models. Here we discuss the introduction and various system models for a better understanding. You may also have a look at the following articles to learn more –

1. Software Development Models
2. Multithreading in Operating System
3. What Is System Design?
4. Alternative to Indesign