EDLC Models

EDLC MODELS

Chapter Structure

Objectives

1 Introduction

2 Waterfall or Linear Model

3 Iterative/ Incremental or Fountain Model

4 Prototyping Model

5 Spiral Model

OBJECTIVES

After reading this chapter you will understand:

Some EDLC Models like:

Waterfall or Linear Model

Iterative/ Incremental or Fountain Model

Prototyping Model

Spiral Model

1 INTRODUCTION

The previous chapters introduced the readers to what is meant by EDLC. This chapter is meant to explain the various models available under the EDLC.

2 WATERFALL MODEL

Linear or waterfall model is the one adopted in most of the olden systems.

In this approach each phase of EDLC (Embedded Development Product Lifecycle) is executed in sequence.

It establishes analysis and design with highly structured development phases.

The execution flow is unidirectional.

The output of one phase serves as the input of the next phase

All activities involved in each phase are well planned so that what should be done in the next phase and how it can be done.

The feedback of each phase is available only after they are executed.

It implements extensive review systems To ensure the process flow is going in the right direction.

One significant feature of this model is that even if you identify bugs in the current design the development process proceeds with the design.

The fixes for the bug are postponed till the support phase.

Advantages

Product development is rich in terms of:

Documentation

Easy project management

Good control over cost & Schedule

Drawbacks

It assumes all the analysis can be done without doing any design or implementation

The risk analysis is performed only once.

The working product is available only at the end of the development phase

Bug fixes and correction are performed only at the maintenance/support phase of the life cycle.

3 ITERATIVE/  INCREMENTAL  OR  FOUNTAIN MODEL

Iterative and Incremental development is at the heart of a cyclic software development process developed in response to the weaknesses of the waterfall model.

The iterative model is the repetitive process in which the Waterfall model is repeated over and over to correct the ambiguities observed in each iteration.

The above figure illustrates the repetitive nature of the Iterative model.

The core set of functions for each group is identified in the first cycle, it is then built, deployed and release. This release is called as the first release.

Bug fixes and modification for first cycle carried out in second cycle.

Process is repeated until all functionalities are implemented meeting the requirements.

Advantages

Good development cycle feedback at each function/feature implementation

Data can be used as reference for similar product development in future.

More responsive to changing user needs.

Provides working product model with at least minimum features at the first cycle.

Minimized Risk

Project management and testing is much simpler compared to linear model.

Product development can be stopped at any stage with a bare minimum working product.

Disadvantages

Extensive review requirement each cycle.

Impact on operations due to new releases.

Training requirement for each new deployment at the end of each development cycle.

Structured and well documented interface definition across modules to accommodate changes

4 PROTOTYPING MODEL

It is similar to iterative model and the product is developed in multiple cycles.

The only difference is that, Prototyping model produces a refined prototype of the product at the end of each cycle instead of functionality/feature addition in each cycle as performed by the iterative model.

There won’t be any commercial deployment of the prototype of the product at each cycle’s end.

The shortcomings of the proto-model after each cycle are evaluated and it is fixed in the next cycle.

After the initial requirement analysis, the design for the first prototype is made, the development process is started.

On finishing the prototype, it is sent to the customer for evaluation.

The customer evaluates the product for the set of requirements and gives his/her feedback to the developer in terms of shortcomings and improvements needed.

The developer refines the product according to the customer’s exact expectation and repeats the proto development process.

After a finite number of iterations, the final product is delivered to the customer and launches in the market/operational environment

In this approach the product undergoes significant evolution as a result of periodic shuttling of product information between the customer and developer

The prototyping model follows the approach-

Requirement definition

Proto-type development

Proto-type evaluation

Requirements  refining

5 SPIRAL MODEL

Spiral model is developed by Barry Boehm in 1988.

The Product development starts with project definition and traverse through all phases of EDLC(Embedded Product Development Life Cycle).

The activities involved are:

Determine objectives, alternatives, constraints

Evaluate alternatives, identify and resolve risks III. Develop and test

IV.    Plan

It is a combines the concept of Linear Model and iterative nature of Prototyping Model.

Prototyping Model

In prototyping after the requirement analysis the design for the prototype is made and development process is started.

On finishing the prototype it is send to the customer for evaluation ie. Judgment.

After customer evaluation for the product the feedback is taken from the customer in term of what improvement is needed.

Then developer refines the product according to the customer expectation.

Linear Model

Spiral Model contains the concept of linear model, having following type.

Requirement

Analysis

Design

Implementation

Requirement:

This process is focused specifically on embedded software, to understand the nature of the software to be build and what are the requirement for the software.

And the requirement for both the system & the software is documented & viewed to customer.

Analysis:

Analysis is performed to develop a detailed functional module under consideration.

The product is defined in detailed with respect to the input, processing & output.

This phase emphasis on determining ‘what function must be performed by the product’ & how to perform those function.

Design:

Product design deals with the entire design of the product taking the requirement into consideration.

The design phase translates requirement into representation.

Implementation:

In this process the launching of first fully functional model of the product in the market is done or handing over the model to an end user/client

In this product modifications are implemented & product is made operational in production environment.