Estimating Work with Use Cases. Estimating Work with Use Cases. We need to forecast. Use Case Point Estimator. We need to quantify

(1)

Desarrollo de Software con UML

Desarrollo de Software con UML Cursada 2004Cursada 2004

Estimating Work with

Use Cases

Desarrollo de Software con UML

Estimating

Work

with

Use Cases

We need to forecast

•

• How

How

long it

long

it

will

take

to

develop

the

system

and

•

• How many people will be needed to do it

How many people will be needed to do it

How long it will take a software engineer to accomplish a

given task is primarily a function of the complexity of

the problem and the engineer

´

s ability

Estimating

Work

with

Use Cases

We need to quantify

•

• The

The

complexity

of

the

system

–

Functionality

–

Technical

complexity

•

• The

The

experience

level

of

the

people

on

the

project

•

• The

The

time

time needed

needed

to

produce a unit

produce a

unit

of

complexity

The goal is to arrive at a single number that completely

characterizes the system and correlates with observed

engineer productivity

Estimating

Work

with

Use Cases

Use Case Point Estimator

•

• An

An

estimating

method

by Gustav

by

Gustav

Karner

of

Rational

Software

Software Corporation

Corporation

–

It characterizes the complexity of a system by

Use Case Points

–

It is preliminary and should be used to get an idea of the

number of man

-

hours for your project

–

It was derived empirically, and the limited amount of

experimentation to date shows that it applies well in

business applications, e.g., information systems

Use Case

Use Case Point

Point

Estimator

This

method

involves

the

following

steps

•

• Calculating

Calculating

the

Unadjusted

Use Case

Use Case Points

Points

–

Weighting

Actors

(UAW) &

Weighting

Use Cases (UUCW)

UUCP

=

ƒ

(

UAW

UAW; UUCW

; UUCW) =

) =

UAW +

UUCW

•

• Calculating Use Case Points

Calculating Use Case Points

–

Weighting

Technical

Factors

(TCF)

–

Weighting

Environmental

Factors

(EF)

UCP

=

ƒ

(

UUCP;

UUCP; TCF; EF

TCF; EF) =

) =

UUCP *

**TCF * EF**

•

• Estimating

Estimating

the

Number

of

Man

Man-

-hours

hours

Man

-

hours

=

ƒ

(

UCP

UCP)

)

An

Example

Customer

Register

Complaint

Get

Catalog

Get

Status

on

Order

Login

Cancel

Cancel Order

Order

Place

Place Order

Order

Return

Product

Run

Sales

Sales Report

Report

Update

Account

Receive

Back

Back-

-ordered

ordered

items

Fill

and

Ship

Order

Customer

Support

Manager

Accounting

System

Inventory

System

Customer

Rep

Update

Product

Quantities

Get

Product

Information

Clerk

Shipping

Company

<< <<includeinclude>>>>

Use Case

Diagram

Order

Processing

System

<< <<includeinclude>>>> << <<includeinclude>>>> << <<includeinclude>>>> << <<includeinclude>>>> << <<includeinclude>>>>

(2)

Calculating the UUCP

Weighting

Actors

•

• Start by considering the actors for the system

Start by considering the actors for the system

determining whether each is simple, average, or

complex based on its interface

Actor Type

Description

Simple

Another system with a defined Application

Programming Interface

Average

Another system interacting through a protocol (e.g.,

TCP/IP) or

A person interacting through a text

-

based interface

(e.g., ASCII Terminal)

Complex

A person interacting through a Graphical User

Interface (stand

-

alone or web application)

Calculating the UUCP

Weighting

Actors

(Cont.)

•

• Count how many of each actor type you have

Count how many of each actor type you have

•

• Then multiply each type by a weighting factor

Then multiply each type by a weighting factor

Actor Type

Factor

Simple

Average

Complex

1

2

3

•

• Finally, add these products together to get a total

Finally, add these products together to get a total

Calculating the UUCP

Weighting

Actors

Order

-

processing

system

•

• Determining whether each actor is simple, average, or

Determining whether each actor is simple, average, or

complex based on its interface

Actor

Type

Customer

Complex

Inventory System

Simple

Accounting System

Simple

Customer Service Manager

Average

Customer Rep

Complex

Clerk

Complex

Shipping Company

Average

Calculating the UUCP

Weighting

Actors

Order

-

processing

system

•

• Count how many of each actor type you have

Count how many of each actor type you have

2 Simple, 2 Average and 3 Complex

•

• Then multiply each type by a weighting factor

Then multiply each type by a weighting factor

2 Simple

*

1

1 =

=

2

2 2 Average

2 Average

*

2

2 =

=

4

4 3 Complex

3 Complex

*

3

3 =

=

9

•

• Finally, add these products together to get a total

Finally, add these products together to get a total

Total Actor Weight

=

15

15 UAW

UAW

Calculating the UUCP

Weighting

Use Cases

•

• For each Use Case determine whether it is simple,

For each Use Case determine whether it is simple,

average or complex

Alternatives:

•

• Transaction

Transaction

-

based or Analysis Class

-

based

•

• Count how many of each type of use case type you have

Count how many of each type of use case type you have

•

• Then, multiply each type by a weighting factor

Then, multiply each type by a weighting factor

•

• Finally, add these products together to get a total

Finally, add these products together to get a total

Calculating the UUCP

Weighting

Use Cases

Transaction

-

based

•

• Determining

Determining

the number of transactions in a use case,

including alternative paths

•

• A transaction is an atomic set of activities, which is

A transaction is an atomic set of activities, which is

either performed entirely or not at all

Use Case

Type

Description

–

It has

Factor

Simple

3 or fewer transactions

5

5 Average

Average

4 to 7 transactions

10

10 Complex

(3)

Order

Processing

System

Name:

Place Order

Brief Description

This Use Case describes the process by which orders are entered into the

order-processing system.

…

Flow of Events

Basic Path

1. The use case begins when the customer selects Place Order in the main screen.

2. The system displays the Place Order screen.

3. The customer enters his or her name and address.

4. The customer enters product codes for products to be ordered.

5. For each product code entered

a)

Include Get Product Information.

b) The system adds the price of the item to the total.

end loop

6. The customer enters credit card payment information.

7. The customer selects Submit.

8. The system verifies the information.

9. The system saves the order as pending –

Include Save Order.

10.

10. Include Update Account.

Include Update Account.

11. The system marks the order as confirmed –

Include Update Order.

12. The system returns an order ID to the customer, and the use case ends.

Use Case Documentation

Order

Processing

System

Name:

Place Order

Brief Description

…

Flow of Events

…

Alternative Paths

• Cancel Placing an Order.

• Payment not there or bad.

• Shipping address incomplete.

• Product code does not match actual products.

• Product no longer carried.

• Customer pays by check.

Alternative Path:

Cancel Placing an Order

Precondition:

The user did not select Submit.

1. The alternative begins when the user selects Cancel.

2. The system discards any entered information.

3. The system returns to the previous display.

4. The use case ends.

Use Case Documentation

Order

Processing

System

Order From Displayed

[ place order selected ]

Enter Name and Address

Give Product Information

[ Product code entered ]

New Total Calculated

[ Product code entered ]

Enter Credit Card Information [ no more product codes ]

Submit Order Marked Pending [ info complete ] Charge Account Order Market Confirmed [ Payment good ] Order ID Displayed

cancel

submit

Cancelable

Actions

Activity

Diagram

(Place

Order

)

C ustomer

Place Order

Save Order

Update Order

Update Account

Get Product Information

<<include>>

Order

Processing

System

Use Case

Context

(Place

Order

)

Calculating the UUCP

Weighting

Use Cases

Analysis Class

-

based

•

• Watching which analysis classes are used to realize a

Watching which analysis classes are used to realize a

particular use case

Use Case

Type

Description

–

It can be realized with

Factor

Simple

Fewer than 5 analysis classes

5

5 Average

Average

5 to 10 analysis classes

10

10 Complex

Complex

More than 10 analysis classes

15

15 Calculating the UUCP

Calculating the UUCP

Weighting

Use Cases

Order

-

proc

system

•

• Determining whether each use case is simple, average,

Determining whether each use case is simple, average,

or complex

Use Case

Type

Place Order

Average

Return Product

Average

Cancel Order

Simple

Get Status on Order

Simple

Send Catalog

Run Sales Report

Simple

Register Complaint

Simple

Fill and Ship Order

Back

-

Ordered Items Received

Average

(4)

Calculating the UUCP

Weighting Use Cases

Order

-

proc system

•

• Count how many of each use case type you have

Count how many of each use case type you have

5 Simple, 4 Average and 0 Complex

•

• Then multiply each type by a weighting factor

Then multiply each type by a weighting factor

5 Simple

*

5

5 =

=

25

25 4 Average

4 Average

*

10

10 =

=

40

40 0 Complex

0 Complex

*

15

15 =

=

0

•

• Finally, add these products together to get a total

Finally, add these products together to get a total

Total Use Case Weight

=

65

65 UUCW

UUCW

Calculating

the

UUCP

Calculating

the

Unadjusted

Use Case

Points

UUCP

=

UAW

+

UUCW

UUCP

Order

-

proc

system

=

15

15 +

+

65

65 =

=

80

80 UUCP provides an idea of the complexity of

UUCP provides an idea of the complexity of

the use cases and interfaces, but

…

What about the technical and environmental

factors?

Calculating the UCP

Technical

Factors

Technical

Factor

Factor Description

Weight

T1

Distributed System

2

2 T2

T2

Response or throughput performance objectives

1

1 T3

T3

End

-

user efficiency (on line)

1

1 T4

T4

Complex internal processing

1

1 T5

T5

Code must be reusable

1

1 T6

T6

Easy to install

0,5

T7

Easy to use

0,5

Calculating the UCP

Technical

Factors

(Cont.)

Technical

Factor

Factor Description

Weight

T8

Portable

2

2 T9

T9

Easy to change

1

1 T10

T10

Concurrent

1

1 T11

T11

Includes special security features

1

1 T12

T12

Provides direct access for third parties

1

1 T13

T13

Special user training facilities required

1

1 Calculating the UCP

Calculating the UCP

Weighting

Technical

Factors

•

• Go through Table and rate each factor from 0 to 5

Go through Table and rate each factor from 0 to 5

A rating of

0 means

that the factor is

irrelevant

A rating of

5 means

that the factor is

essential

A rating of

3 means

that the factor is

average

•

• Then multiply each factor´

Then multiply each factor

´s rating (

s rating (TLevel

TLevel) by its weight

) by its weight

•

• Finally, add these products together to get a total

Finally, add these products together to get a total

(

(TFactor

TFactor)

)

Calculating the UCP

Weighting

Technical

Factors

Order

-

proc

system

Technical

Factor

Weight

TLevel

* Weight

Reason

T1

T1 22 11 22 Just ClientJust Client--ServerServer T2

T2 11 33 33 Speed is likely limited by input humanSpeed is likely limited by input human T3

T3 11 55 55 Needs to be efficient Needs to be efficient T4

T4 11 11 11 Easy processingEasy processing

T5

T5 11 00 00 Nice, but laterNice, but later

T6

T6 0,50,5 55 2,52,5 Needs to be easy for nonNeeds to be easy for non--technical technical people people T7

T7 0,50,5 55 2,52,5 Needs to be easy for nonNeeds to be easy for non--technical technical people people T8

T8 22 00 00 Not at this time Not at this time T9

T9 11 33 33 SureSure

T10

T10 11 55 55 Not exactly, but it is multiNot exactly, but it is multi--useruser T11

T11 11 33 33 Simple securitySimple security T12

T12 11 55 55 CustomersCustomers

T13

T13 11 00 00 So easy we donSo easy we don’’t need trainingt need training

TFactor

(5)

Calculating the UCP

Weighting

Technical

Factors

Order

-

proc

system

TFactor

=

∑

(

TLevel

*

Weight

)

=

32

32 TCF

TCF

=

0,6

+

(

0,01

*

TFactor

)

TCF

=

0,6

+

(

0,01

*

32

32 )

)

=

0,92

Calculating the UCP

Environmental

Factors

Environmental

Factor

Factor Description

Weight

E1

Familiar with Rational Unified Process

1,5

E2

Application experience

0,5

E3

Object

-

oriented experience

1

1 E4

E4

Lead analyst capability

0,5

E5

Motivation

1

1 E6

E6

Stable requirements

2

2 E7

E7

Part

-

time workers

-

1

1 E8

E8

Difficult programming language

-

1

1 Calculating the UCP

Calculating the UCP

Weighting

Environmental

Factors

•

• Go through Table and rate each factor from 0 to 5

Go through Table and rate each factor from 0 to 5

For factors E1 through E4

A rating of 0 means no experience in the subject

5 means expert; 3 means average

For E5 (Motivation)

0 means no motivation for the project;

5 means high motivation

For E6 (Stable Requirements)

0 means extremely unstable requirements;

5 means unchanging requirements

For E7 (Part

-

time Workers)

0 means no part

-

time technical staff;

5 means all part

-

time technical staff

For E8 (Programming Language)

0 means easy

-

to

-

use programming language;

5 means very difficult programming language

Calculating the UCP

Weighting

Environmental

Factors

•

• Then multiply each factor´

Then multiply each factor

´s rating (

s rating (ELevel

ELevel) by its weight

) by its weight

•

• Finally, add these products together to get a total

Finally, add these products together to get a total

(

(EFactor

EFactor)

)

Calculating the UCP

Weighting

Environm

.

Factors

Order

-

proc

system

Environm

.

Factor

Weight

ELevel

*

Weight

Reason

E1

1,5

1

1 1,5

1,5

Most of team unfamiliar

E2

0,5

3

3 1,5

1,5

Most of team are programmers

E3

1

3

3 …

…

OO programmers

E4

0,5

5

5 2,5

2,5

The leader is really good

E5

1

5

5 Team is really eager

Team is really eager

E6

2

5

10

10 We don

We don

’

t expect changes

E7

-

1

0

0 Not part

Not part

-

timers

E8

-

1

3

3 -

-

3

3 We

We

’

re looking at Java

EFactor

=

∑

ELevel

*

Weight

20,5

Calculating the UCP

Weighting

Environm

.

Factors

Order

-

proc

system

EFactor

=

∑

(

ELevel

*

Weight

)

=

20,5

EF

=

1,4

+

(

-

0,03

*

EFactor

)

EF

(6)

Calculating

the

UCP

Calculating

the

Use Case

Points

UCP

=

UUCP

*

TCF

*

EF

UCP

Order

-

proc

system

=

80

80 *

*

0,92

*

0,785

=

57,77

UCP provides an idea of the complexity of the

system adjusted to the technical and environmental

factors

Estimating the Project

Estimating

Man

-

hours

•

• In general, Karner

In general,

Karner

suggests using

suggests using 20 man

20 man

-

hours per UCP

Man

Man-

-hours

hours

Order

-

proc system

=

57,77

*

20

20 = 1155,52

= 1155,52

~ 29 weeks at 40 hours a week, for one person

Taking a small team of 6 persons working full

-

time

~ 5 weeks of effort

•

• Add some weeks for working out any team issues

Add some weeks for working out any team issues

–

Too many problems of communication or synchronization

Estimating the Project

Estimating

Man

-

hours

•

• Schneider & Winters suggest

Schneider & Winters suggest a refinement based on

a refinement based on

Environmental Factors

–

EF factors measure the experience level of your staff and

the stability of your project.

–

Any negatives in this area mean that you will have to spend

time training people or fixing problems due to instability.

Estimating the Project

Estimating

Man

-

hours

•

• Schneider & Winters suggest a refinement based on EF

Schneider & Winters suggest a refinement based on EF

–

Start by Calculating TNEF:

Count how many of E1 through E6 are below 3 (average

level value) and how many in E7 and E8 are above 3.

–

Then, you have to use:

•

20

20 man

man

-

hours per UCP

when TNEF ≤ 2

•

28

28 man

man

-

hours per UCP

when 3 ≤ TNEF ≤ 4

•

36

36 man

man

-

hours per UCP

when TNEF ≥ 4

=> In this case, try very hard to change your project

Calculating the UCP

Weighting

Environm

.

Factors

Order

-

proc

system

Environm

.

Factor

Weight

ELevel

*

Weight

Reason

E1

1,5

1

1 1,5

1,5

Most of team unfamiliar

E2

0,5

3

3 1,5

1,5

Most of team are programmers

E3

1

3

3 …

…

OO programmers

E4

0,5

5

5 2,5

2,5

The leader is really good

E5

1

5

5 Team is really eager

Team is really eager

E6

2

5

10

10 We don

We don

’

t expect changes

E7

-

1

0

0 Not part

Not part

-

timers

E8

-

1

3

3 -

-

3

3 We

We

’

re looking at Java

We have one EF below the average

=> 20 man

-

hours per UCP

It is below 3

Book

•

• Applying Use Cases: A Practical Guide

Applying Use Cases: A Practical Guide

Authors: G.Schneider & J. P. Winters

Edition: Second

-

Editorial: Addison Wesley

ISBN: 0

-

2001

-

70853

-

1

1 References

References

Papers

•

• Resource Estimation for

Resource Estimation for

Objectory

Projects

G.

G. Karner

Karner

-

Objectory

Systems

•

• The Estimation of Effort Based on Use Cases

The Estimation of Effort Based on Use Cases

J. Smith