loc, cocomo i & cocomo ii kalyan mondal (2012ca49) jyoti shrivastava (2012ca52) kamal kishore...

LOC, COCOMO I & COCOMO II

Kalyan Mondal (2012ca49)

Jyoti Shrivastava (2012ca52)

Kamal Kishore (2012ca34)

Jyotsna Agnihotri (2012ca66)

Karishma Gupta(2012ca55)

Presented By: Subject: Software EngineeringCoordinator:Mr Anoj Kumar

Contents Software Planning LOC: Lines of Code Function Point Cost Estimation Development Mode COCOMO I

• Basic COCOMO• Intermediate COCOMO• Detailed COCOMO

COCOMO II• Application Composition• Early Design Model• Post Architecture Model

References

SOFTWARE PLANNINGSoftware planning begins before technical work starts, continues as the softwareEvolves from concept to reality, and culminates only when the software is retired.

Created by:- Kamal kishore(2012ca34)Ref :-software engineering by K.K.Agrawal, yogesh singh

Fig:- Activities during software project planning

LINES OF CODE(LOC)

• A Line of code is any line of program text that is not a comment or blank line, regardless of the number of statements or fragments on the line. This specifically includes all lines containing program header, declarations, and executable and non-executable statements.• While line of codes have their uses, their usefulness is limited for other tasks like functionality, complexity, efficiency, etc.


FUNCTION POINTFunction point measures functionality which is a solution to the size measurement problem.It is decomposed into following functional units


InputsOutputsEnquiriesInternal Logical Files

External Interface

Files

FUNCTIONAL UNITS WITH WEIGHTING FACTORS

Functional units Low Average

High

External Inputs 3 4 6

External Outputs 4 5 7

External Inquiries 3 4 5

Internal logical files (ILF)

7 10 15

External interface files (EIF)

5 7 10The procedure for the calculation of UFP in mathematical form is given below

5 3UFP = ∑ ∑ UFP : Unadjusted Function Point i=1 j=1Where i indicates the row and j indicates the column of table.Wij : It is the entry of ith row and jth column of the table. Zij: It is the count of the number of functional unit of type i that have been classified as having the complexity corresponding to column j


An exampleConsider a project with the following functional units: 50 user inputs,40 user outputs, 35 user enquiries,6 user files,4 external interfaces. Assume all complexity adjustment factors and weighting factors are average.Compute the function points for the project. Suppose that program needs 70 LOC per FP. Find out the size of complete project.

Solution:5 3

UFP = ∑ ∑ i=1 j=1

UFP= 50 * 4 + 40 * 5 + 35 * 4 + 6 * 10 + 4 * 7 = 200+200+140+60+28 = 628CAF= (0.65 + ∑

=(0.65 + 0.01 (14 * 3 )) = 1.07FP= UFP * CAF

=628 * 1.07 = 672Size = FP * (LOC per FP) = 672 * 70 = 47040 LOC

Created by:- Kamal kishore(2012ca34)Ref :-software engineering by K.K.Agrawal, Yogesh Singh

Cost EstimationApproximate judgement of the costs for a

project. It should be done throughout the entire life cycle.

Why we need? To determine how much effort and time a

software project requires.Important for making good management

decisions.It facilitates competitive contract bids. It affect the planning and budgeting of a

project.

Ref: Software Engineering By K.K.Aggarwal & Y. Singh Created by: Jyoti Shrivastava

Development Mode of S/W ProjectsMode Project

SizeNature of Project Innovatio

nDeadline

Organic Typically2-50 KLOC

Small size project, Experienced developers.

Little Not Tight

Semi Detached

Typically50-300KLOC

Medium size project and team.

Medium Medium

Embedded

Typically over 300KLOC

Large project, Real-time systems

Significant

Tight

Constructive Cost Model(COCOMO )

The COCOMO model is a single variable software cost estimation model developed by Barry Boehm in 1981.

The model uses a basic regression formula, with parameters that are derived from historical project data and current project characteristics.

Hierarchy of Cocomo Model1. Basic COCOMO model2. Intermediate COCOMO model3. Detailed COCOMO model


Basic COCOMO ModelIt take the form:

Effort(E) = ab * (KLOC)bb(in Person-months)

DevelopmentTime(D) = cb * (E) db (in month)

Average staff size(SS) = E/D (in Person)

Productivity(P) = KLOC / E (in KLOC/Person-month)Project ab bb cb db

Organic 2.4 1.05 2.5 0.38

Semidetached

3.0 1.12 2.5 0.35

Embedded 3.6 1.20 2.5 0.32


Person-Months

What is Person-Months ?The area under the curve

Ref: Fundamentals of Software Engineering By Rajib Mall Created by: Jyoti Shrivastava

Basic cocomo: ExampleA project size of 200KLOC is to be developed.S/W development team has average experience on similar type of projects.The project schedule is not very tight.Calculate the effort and development time of the project.Ans: 200 KLOC implies semi-detached mode.

Hence, E= 3.0 * (200)1.12 = 1133.12 PMD=2.5 * (1133.12)0.35 = 29.3 MAvg. staff size(SS) = E/D

= 1133.12/29.3=38.67 Persons.Productivity (P) = KLOC/E

= 200/1133.12=0.1765 KLOC/PM.


Intermediate COCOMO Extension of Basic COCOMO Why Use ?

Basic model lacks accuracy Computes software development effort as a function of

program size and set of 15 Cost Drivers Cost Driver: A multiplicative factor that determines the

effort required to complete the software project. Why Cost Drivers?

Adjust the nominal cost of a project to the actual project Environment.

For each Characteristics, Estimator decides the scale factor

Ref: Software Engineering By K.K.Aggarwal & Y. Singh Created by: Kalyan Mondal

Very Low Low Nominal High Very

HighExtra High

Cost Drivers

•Required Software Reliability (RELY)

•Database Size (DATA)

•Product Complexity (CPLX)

Product Attributes

•Execution Time Constraint (TIME)

•Main Storage constraint (STOR)

•Virtual Machine volatility (VIRT)

•Computer turnaround time (TURN)

Computer Attributes

•Analyst Capability (ACAP)

•Application Experience (AEXP)

•Programmer Capability (PCAP)

•Virtual Machine Experience (VEXP)

•Programming language Experience (LEXP)

Personnel Attributes

•Modern programming practices (MODP)

•Use of Software tools (TOOL)

•Required development schedule (SCED)

Project Attributes


The Calculation Multiply all 15 Cost Drivers to get Effort

Adjustment Factor(EAF)

E(Effort) = ab(KLOC)bb * EAF(in Person-Month)

D(Development Time) = cb(E)db (in month)

SS (Avg Staff Size) = E/D (in persons)

P (Productivity) = KLOC/E (in KLOC/Person-month)

Project ab bb cb db

Organic 3.2 1.05 2.5 0.38

Semidetached

3.0 1.12 2.5 0.35

Embedded 2.8 1.20 2.5 0.32


Intermediate COCOMO : Example

A new project with estimated 400 KLOC embedded system has to be developed. Project manager hires developers of low quality but a lot of experience in programming language. Calculate the Effort, Development time, Staff size & Productivity.

EAF = 1.29 * 0.95 = 1.22

400 LOC implies Embedded System

Effort = 2.8*(400)1.20 * 1.225 = 3712 * 1.22 = 4528 person-months

Development Time = 2.5 * (4528)0.32 = 2.5 * 14.78 = 36.9 months

Avg. Staff Size = E/D = 4528/36.9 = 122 persons

Productivity = KLOC/Effort = 400/4528 = 0.0884 KLOC/person-month

Cost Drivers

Very Low

Low Nominal

High

Very High

Extra High

AEXP 1.29 1.13 1.00 0.91 0.82 --

LEXP 1.14 1.07 1.00 0.95

-- --


Detailed COCOMO Detailed COCOMO = Intermediate COCOMO +

assessment of Cost Drivers impact on each phase.

Phases1) Plans and requirements

2) System Design

3) Detailed Design

4) Module code and test

5) Integrate and test

• Cost of each subsystem is estimated separately. This reduces the margin of error.


The Calculation Multiply all 15 Cost Drivers to get Effort

Adjustment Factor(EAF)

E(Effort) = ab(KLOC)bb * EAF(in Person-Month)

D(Development Time) = cb(E)db (in month)

Ep (Total Effort) = µp * E (in Person-Month)

Dp (Total Development Time) = τp * D (in

month)


Detailed COCOMO : ExampleConsider a project to develop a full screen editor. The major components identified and their sizes are (i) Screen Edit – 4K (ii) Command Lang Interpreter – 2K (iii) File Input and Output – 1K (iv) Cursor movement – 2K (v) Screen Movement – 3K. Assume the Required software reliability is high, product complexity is high, analyst capability is high & programming language experience is low. Use COCOMO model to estimate cost and time for different phases.

Size of modules : 4 + 2 + 1 + 2 + 3 = 13 KLOC [Organic]

EAF = 1.15 * 1.15 * 0.86 * 1.07 = 1.2169

Cost Drivers

Very Low

Low Nominal

High

Very High

Extra High

RELY 0.75 0.88 1.00 1.15

1.40 --

CPLX 0.70 0.85 1.00 1.15

1.30 1.65

ACAP 1.46 1.19 1.00 0.86

0.71

LEXP 1.14 1.07 1.00 0.95 -- --


Example (Contd.)Initial Effort (E) = ab(KLOC)b

b * EAF = 3.2*(12)1.05 * 1.2169 = 52.9 person-months

Initial Development Time = cb(E)db =2.5*(52.9)0.38 =

11.29 months

Phase value of µp and τp

Phase wise effort & development time distribution

Plan &

Reqr

System

Design

Detail Desig

n

Module code &

test

Integration & Test

Organic Small µp

0.06 0.16 0.26 0.42 0.16

Organic Small τp

0.10 0.19 0.24 0.39 0.18


E D Ep (in person-months)

Dp (in months)

Plan & Requirement

52.9 11.29 0.06*52.9 = 3.17

0.10*11.29=1.12

System Design 52.9 11.29 0.16*52.9=8.46 0.19*11.29=2.14

Detail Design 52.9 11.29 0.26*52.9=13.74

0.24*11.29=2.70

Module code & test

52.9 11.29 0.42*52.9=22.21

0.39*11.29=4.40

Integration & test

52.9 11.29 0.16*52.9=8.46 0.18*11.29=2.03

WHY COCOMO-II ? The changes in s/w development techniques

included a move away from mainframe overnight batch processing to desktop-based real-time turnaround.

These changes and others began to make applying the original COCOMO model problematic.

The model is tuned to the life cycle practices of the 21st century.

Ref: Software Engineering By K.K.Aggarwal & Y. Singh and csse website by : Jyotsna Agnihotri

Categories Identified By Cocomo II

End User ProgrammingInfrastructure SectorIntermediate Sectors

1. Application Generators And Composition Aids2. Application Composition Sector3. System Integration

Stages Of Cocomo-IIApplication CompositionEarlier DesignPost Architecture

Ref: Software Engineering By K.K.Aggarwal & Y. Singh by : Jyotsna Agnihotri

Application CompositionAssess Object Counts

Classification Of Complexity

LevelsAssign Complexity

Weight To Each Object

Determine Object Points

Compute New Object Points

Calculation Of Productivity

Rate

Compute The Effort In Person

Months.

• Assess object counts: Estimate the number of screens, reports and 3 GL components that will comprise this application.

• Classification of complexity levels: We have to classify each object instance (depending on values of its characteristics) into :-

o simpleo medium o Difficult

• Assign complexity weight to each object : The weights are used for three object types :-o screeno report o 3GL components


• Determine object points: Add all the weighted object instances to get one number and this known as object-point count.

• Compute new object points: We have to estimate the percentage of reuse to be achieved in a project. Depending on the percentage reuse, the new object points (NOP) are computed.

Object Points * (100 - %reuse)

NOP = ---------------------------------------------

100

NOP are the object points that will need to be developed and differ from the object point count because there may be reuse( percentage of the Product development which is accomplished by exploiting the existence of existing component's design-or-development effort).

Ref: Software Engineering By K.K.Aggarwal & Y. Singh&gilb.com by : Jyotsna Agnihotri

http://www.gilb.com/definition-Product&structure=Glossary&page_ref_id=487

• Calculation of productivity rate: The productivity rate can be calculated as:

Productivity rate (PROD) = NOP/Person month

• Compute the effort in Persons-Months: When PROD is known, we may estimate effort in Person-Months as:

NOP Effort in PM = ------------

PROD


Example: Consider a database application project with the following characteristics:

The application has 4 screens with 4 views each and 7 data tables for 3 servers and 4 clients.

The application may generate two report of 6 sections each from 07 data tables for two server and 3 clients. There is 10% reuse of object points.

The developer’s experience and capability in the similar environment is low. The maturity of organization in terms of capability is also low. Calculate the object point count, New object points and effort to develop such a project.

Example


Solution :Lets have a look on the tables for screens, for reports , for complexity weights for each level

No. Of Views Contained in a screen

Total<4(<2 servers<3 clients)

Total<8(2-3 servers3-5 clients)

Total 8+(>3 servers>5 clients)

<3 Simple Simple Medium

3-7 Simple Medium Difficult

>8 Medium Difficult Difficult

No. Of SectionsContained in a report

Total<4(<2 servers<3 clients)

Total<8(2-3 servers3-5 clients)

Total 8+(>3 servers>5 clients)

0 or 1 Simple Simple Medium

2 or 3 Simple Medium Difficult

4+ Medium Difficult Difficult

This project comes under the category of application composition estimation model.

Number of screens = 4 with 4 views each Number of reports = 2 with 6 sections each From Table we know that each screen will be of medium complexity

and each report will be difficult complexity. Using Table of complexity weights, we may calculate object point

count

= 4 x 2 + 2 x 8 = 24


Object Type

Simple Complexity

MediumComplexity

Difficult Complexity

Screen 1 2 3

Report 2 5 8

3GL - - 10

Using the formula NOP is calculated as:

NOP= 24 * (100-10)/100=21.6

Low value of productivity is given in above Productivity table = 7

Efforts in PM=NOP/PROD=21.6/7=3.086 PM

Developer’s Experience And Capability

PROD (NOP/PM)

Very low 4

Low 7

Nominal 13

High 25

Very high 50


32

Early Design ModelUsed in the early stages of a software project when very little may be known about:

the size of the product to be developed, the nature of the target platform, the nature of the personnel to be involved in the project.

Uses Unadjusted Function Points (UFP) as the measure of size.Based on a standard formula for COCOMO-II models:

WherePMnominal = Effort of the project in person monthsA = Constant representing the nominal productivity, provisionally set to 2.5B = Scale factorSize = Software size

Created by- Karishma Gupta (2012CA55) Ref: Software Engineering By K.K. Aggarwal & Yogesh Singh

33

The Scaling Factors that COCOMO-II model uses for thecalculation of B are: Precedentness (PREC) Development flexibility (FLEX) Architecture/ Risk Resolution (RESL) Team Cohesion (TEAM) Process maturity (PMAT)

Early design cost driversThere are 7 early design cost drivers and are given below:

1. Product Reliability and Complexity (RCPX) 2. Required Reuse (RUSE)3. Platform Difficulty (PDIF)4. Personnel Capability (PERS)5. Personnel Experience (PREX)6. Facilities (FCIL)7. Schedule (SCED)


Data for the Computation of B (Scalar Factor)

Scaling Factors Very Low Low Nominal High Very High Extra High

Precedentness 6.20 4.96 3.72 2.48 1.24 0.00

Development Flexibility

5.07 4.05 3.04 2.03 2.03 0.00

Architecture/ Risk Resolution

7.07 5.65 4.24 2.83 1.41 0.00

Team Cohesion 5.48 4.38 3.29 2.19 1.10 0.00

Process Maturity

7.80 6.24 4.68 3.12 1.56 0.00


If B=1.0, then Linear relationship b/w Effort & Size.If B 1.0, then Non-Linear relationship b/w Effort & Size.

If B<1.0, then the rate of increase of effort decreases as the size of the product increases.

If B>1.0, then the rate of increase of effort increases as the size of the product increases.

B = 0.91 + 0.01 * (Sum of rating on scaling factors for the project)

When all the scaling factors of a project are rated as extra high, then the best value of B= 0.91 (for COCOMO II.2000)

when all the scaling factors of a project are rated as very low,Then the worst value of B= 1.23 (for COCOMO II.2000)Hence, the value of B may vary from 0.91 to 1.23


Calculate the scalar factor B

36

Early Design Model: ExampleQuestion: A software project of application generator category with estimated 50 KLOC has to be developed. The scale factor (B) has low precedentness, high development flexibility and low team cohesion.

Other factors are nominal. The early design cost drivers like platform difficult (PDIF) and Personnel Capability (PERS) are high and others are nominal.

Calculate the Effort in person-months for the development of the project.


Early Design Cost Drivers

Extra Low

Very Low

Low Nominal High Very High

Extra High

RCPX 0.73 0.81 0.98 1.0 1.30 1.74 2.38

RUSE - - 0.95 1.0 1.07 1.15 1.24

PDIF - - 0.87 1.0 1.29 1.81 2.61

PERS 2.12 1.62 1.26 1.0 0.83 0.63 0.50

PREX 1.59 1.33 1.12 1.0 0.87 0.71 0.62

FCIL 1.43 1.30 1.10 1.0 0.87 0.73 0.62

SCED - 1.43 1.14 1.0 1.0 1.0 -

37

B = 0.91 + 0.01 * (Sum of rating on scaling factors for the project) = 0.91 + 0.01 * (4.96 + 2.03 + 4.24 + 4.38 + 4.68) = 0.91 + 0.01(20.29)=1.1129

= 2.5 * (50)1.1129 = 194.41 Person-months

here A=2.5 (for COCOMO II.2000) predefined The 7 cost drivers are:

PDIF = high (1.29) PERS = high (0.83)

RCPX = nominal (1.0) RUSE = nominal (1.0)PREX = nominal (1.0) FCIL = nominal

(1.0)SCEO = nominal (1.0)

Solution :

= 194.41 * [1.29 x 0.83]= 194.41 x 1.07= 208.155 Person months


Post Architecture Model• Most detailed estimation model.• Used when a software life cycle architecture has been completed. • Used in the development and maintenance of software products in the application generators, system integration or infrastructure sectors.

WhereEM : Effort multiplier which is the product of 17 cost drivers.PMnominal = Effort of the project in person months.

Lines of Codes Counting RulesFunction PointsCost Drivers

38Created by- Karishma Gupta (2012CA55) Ref: Software Engineering By K.K. Aggarwal & Yogesh Singh

39

Cost Drivers of Post Architecture

•Required Software Reliability (RELY)

•Database Size (DATA)

•Product Complexity (CPLX)

•Documentation (DOCU)

•Required Reusability (RUSE)

Product Attributes

•Execution Time Constraint (TIME)

•Platform Volatility (PVOL)

•Main Storage constraint (STOR)

Computer Attributes

•Analyst Capability (ACAP)

•Personnel Continuity (PCON)

•Programmer Experience (PEXP)

•Programmer Capability (PCAP)

• Analyst Experience(AEXP)

•Language & Tool Experience (LTEX)

Personnel Attributes

•Use of Software tools (TOOL)

•Required development schedule (SCED)

•Site Locations & Communications Technology b/w sites (SITE)

Project Attributes


Added Cost Drivers

7 cost drivers DOCU RUSE PVOL PLEX LTEX PCON SITE

Deleted Cost Drivers

5 Cost Drivers• VIRT• TURN• VEXP• LEXP• MODP


Cost Drivers

Very Low Low Nominal High Very High Extra High

RELY 0.75 0.88 1.00 2.48 1.24 0.00

DATA 0.93 1.00 2.03 2.03 0.00

CPLX 0.75 0.88 1.00 2.83 1.41 0.00

RUSE 0.91 1.00 2.19 1.10 0.00

DOCU 0.89 0.95 1.00 3.12 1.56 0.00

TIME 1.00 1.11 1.31 1.67

STOR 1.00 1.06 1.21 1.57

PVOL 0.87 1.00 1.15 1.30

ACAP 1.50 1.22 1.00 0.83 0.67

PCAP 1.37 1.16 1.00 0.87 0.74

PCON 1.24 1.10 1.00 0.92 0.84

AEXP 1.22 1.10 1.00 0.89 0.81

PEXP 1.25 1.12 1.00 0.88 0.81

LTEX 1.22 1.10 1.00 0.91 0.84

TOOL 1.24 1.12 1.00 0.86 0.72

SITE 1.25 1.10 1.00 0.92 0.84 0.78

SCED 1.29 1.10 1.00 1.00 1.00

17 Cost Drivers


42

Schedule Estimation

Development time can be calculated using PMadjusted as a key factor and the desired equation is:

Where= constant, provisionally set to 3.67, B = Scaling factor

TDEVnominal = calendar time in months with a scheduled constraintPMadjusted = Estimated effort in Person months (after adjustment)

Size can be measured in any unit and the model can be calibratedaccordingly. However, COCOMO II details are:I. Application composition model uses the size in object points.II. The other two models use size in KLOC.

Size Measurement


43

Post Architecture: ExampleQues: A software project of application generator category with estimated 50 KLOC has to be developed. The scale factor (B) has low precedentness, high development flexibility and low team cohesion. The identified 17 Cost drivers are high reliability (RELY), very high database size (DATA), high execution time constraint (TIME),very high analyst capability (ACAP), high programmers capability (PCAP).The other cost drivers are nominal. Calculate the effort in Person-Months for the development of the project.

Here B = 1.1129PMnominal = 194.41 Person-months

= 194.41 x (1.15 x 1.19 x 1.11 x 0.67 x 0.87)= 194.41 x 0.885= 172.05 Person-months

Solution :


Final Word“The models are just there to help, not to make the management decisions for you.”

--Barry Boehm

Ref: https://cs.uwaterloo.ca/~apidduck/se362/Lectures/cocomo.pdf

ReferencesSoftware Engineering (Third Edition) By

K.K.Aggarwal & Y. SinghFundamentals of Software Engineering (Third

Edition) By Rajib MallSoftware Engineering , 6th Edition By Ian

SommervilleSoftware Engineering (Sixth Edition) by

Roger S. Pressmanhttps://cs.uwaterloo.ca/~apidduck/se362/

Lectures/cocomo.pdf

Thank You

loc, cocomo i & cocomo ii kalyan mondal (2012ca49) jyoti shrivastava (2012ca52) kamal kishore...

Documents

yogesh singh slide

contents software planning

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size of complete project

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kloc small size project

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