Lecture 2 Software Process & Models

8/11/2019 Lecture 2 Software Process & Models

1/21

Chapter : Software Process


2/21

The Software Challenge


3/21

Q : If you have to write a 10,000 line program in C to solve a problem, how long will it

take?A: Generally range from 24 months

Let us analyze the productivity

Productivity = Output/Input resources

In SW

Output = LoC

Input resources = effort

= person months;

[overhead cost modeled in rate for person month]The productivity is 2.55 KLOC/PM.

Q: What is the productivity in a typical commercial SW organization?

A:Between 100 to 1000 LOC/PM. So, need to raise the productivity.

Introduction Jaypee Institute of Information Technology

The Software Challenge


4/21

Rough cost estimate

Productivity = 500 LOC/PM Cost to the company = $10K/PM

Cost per LOC = $20

So each line of delivered code costs about $20.

A simple application for a business may have 20KLOC to 50KLOC

Cost = $100K to $1Million

Can easily run on $10K$20K hardware

So HW costs


5/21


Software is Expensive


6/21


Software is Expensive

Moores law:processor speed/memory capacitydoubles every two years.


7/21

As per the IBM report,

31%of the project get cancelled before they are completed,

53% overruntheir cost estimates by an average of 189% and

for every 100 projects, there are 94 restarts.


Software Crisis


8/21


Software Failure Curve


9/21

The problem of producing software to satisfy user-needs drives the approaches used in SE

SE (IEEE): Systematic approach to development,., of software.

Systematic approach: Methodologies and practices that can be used to solve a

problem from problem domain

Q:What other factors that drive the selection of a SE approach?

1. scale,2. productivity,

3. quality,

4. consistency,

5. rate of change,


What is Software Engineering

(1) The application of a systematic, disciplined, quantifiable approach to the development,

operation, and maintenance of software; that is, the application of engineering to

software.

(2) The study of approaches as in (1). - IEEE Definition


10/21


Iron Triangle


11/21


Iron Triangle - Violation

What happens when you break the triangle?

1) The project gets canceled.

2) The Project is deliver late, over budget, or both

3) The Project delivers poor quality software.

When development teams are forced to deliver more functionality than they have timeor resources for, they are often motivated to take short cuts which inevitably result in

poor quality.

4) The project under delivers.

The team fails to deliver all of the required functionality.

Recognize that the iron triangle must be respected.


12/21

The Software Engineering Institute (SEI) has developed process meta-model to

measure organizationslevel of process capability and maturity.

CMMIdeveloped by SEI

The CMMI defines each process area in terms of specific goals and the specific

practicesrequired to achieve these goals.

Specific goalsestablish the characteristics that must exist if the activities implied

by a process area are to be effective.

Specific practicesrefine a goal into a set of process-related activities.

Capability Maturity Model Integration (CMMI)



13/21

Level 1 (Initial)

Characterized as ad hoc, and occasionally even chaotic Few processes are defined, and success depends on individual effort

Level 2 (Repeatable / Managed)

Basic project management processes are established to track cost, schedule, and

functionality

The necessary process discipline is in place to repeat earlier successes on projects

with similar applications

Level 3 (Defined)

The software process for both management and engineering activities is

documented, standardized, and integrated into a standard software processfor the

organization

All projects use an approved, tailored version of the organization's standard

software process for developing and maintaining software




14/21

Level 4 (Quantitatively Managed)-

All level 3 criteria have been satisfied.

Detailed measures of the software process and product quality are collected

Both the software process and products are quantitatively understood and controlled

Level 5 (Optimized)

Continuous process improvement is enabled by quantitative feedback from the process and

testing innovative ideas.

http://en.wikipedia.org/wiki/Capability_Maturity_Model_Integration


http://en.wikipedia.org/wiki/Capability_Maturity_Model_Integrationhttp://en.wikipedia.org/wiki/Capability_Maturity_Model_Integrationhttp://en.wikipedia.org/wiki/Capability_Maturity_Model_Integrationhttp://en.wikipedia.org/wiki/Capability_Maturity_Model_Integrationhttp://en.wikipedia.org/wiki/Capability_Maturity_Model_Integrationhttp://en.wikipedia.org/wiki/Capability_Maturity_Model_Integrationhttp://en.wikipedia.org/wiki/Capability_Maturity_Model_Integrationhttp://en.wikipedia.org/wiki/Capability_Maturity_Model_Integration


15/21




16/21

Software Process

(IEEE) A sequence of steps (activities, methods, practices, and transformations)performed

for a given purpose(develop and maintain software)

Steps:

Specification

Design and Implementation

Validation

Evolution

A softwareprocess modelis an abstract representation of a process.

It presents a description of a process from some particular perspective


17/21

SOFTWARE PROCESS MODELS


18/21

Self Study - Terminologies


19/21



20/21



21/21


Lecture 2 Software Process & Models

Documents

Transcript of Lecture 2 Software Process & Models