How Can You Improve Your As-is Models? Requirements Analysis Methods Meet GQM

transcript

How Can You Improve Your As-is Models?Requirements Analysis Methods Meet GQM

Tokyo Institute of Technology, Japan

Shoichiro Ito, Shinpei Hayashi,and Motoshi Saeki

How Can You Improve Your As-is Models?Requirements Analysis Methods

Meet GQM

Topic: Detecting problems in As-isand deriving To-be by solving them

We use an integrated model on:Goal-oriented analysis +Problem frame approach +Use case modeling

Finding problems in integrated modelsusing metrics derived via GQM

Abstract

Backgroundl Information systems (ISs) should enhance their

business valuel To develop ISs providing high business value:– Clarify the current situation (As-is) of business process– Identify the problems hidden in the current situations– Develop a new version of ISs (To-be)

We need techniques to support the identification of the problems, which can be seamlessly connected to the modeling techniques.

Modeling TechniquesGoal-Oriented Requirements Analysis

l Often used in As-is analysis– Refines/decomposes abstract

goals to concrete– Defines alternatives as

OR-decomposed goals

l Pros– Clarifies the rationale of

requirements (bottom-to-up)

l Cons– Hard to express

systems’ behavior4

Refines/decomposes goalsClarifies the rationales of requirements

Efficient road network

Traffics managedusing lights

GORA: Goal model

Our Solution:

GORA: Goal model

Problem Frame: Context diag.

For understanding systems’ behaviorClarifies the boundary between

machines and environments

LightsController

LightUnits(LU)

LightCycle

Integrated Model

Use case modeling: Use case descriptionProvides sequence of steps of each functionalitywhich can be a glue to connect two modeling techniques

Identify problems in an integrated model w/ metrics via GQM

Constructa model

Refinegoals

Identifyproblemsfound

Notfound

Our Approach

l 4 steps incl. iteration1. Construct an As-is model2. Identify its problems3. Refine goals4. Construct a To-be model

Home deliverypizza

Receive orders

Can order with anequipment anyone has

Easy to orderfor customers

Receive ordersby telephone

Deliver pizzas

Get payment

Stock control

Example Goal Model:Home Delivery Pizza

Step 1: Construct As-isl As an integrated model– A goal model (GM)– Use case descriptions (UCDs)– A context diagram (CD)

GM UCDs CD

Constructa model

Refinegoals

Identifyproblems

Notfound

Integration Rule

Use case:Receive ordersby telephone

Precondition:Telephone ringing

Basic flow:1. Pick up telephone2. (Get) Name, telephone

number, address3. (Get) Order4. Ring off telephone5. Write an invoice

l Each leaf goal in GM ó a UC ó a UCDl Each step in UCD ó an event in CD

Staff (S)

Customer (C)

C! Ring offtelephone

<<human>>

Integrated Model (As-is)

Staff (S)

Customer (C)

Invoice (I)S! Write an invoice

C! Telephone ringing

C! Order

C! Ring off telephone

C! Name, telephone number, address

Use case: Receive orders by telephonePrecondition: Telephone ringingBasic flow:

1. Pick up telephone2. (Get) Name, telephone number, address3. (Get) Order4. Ring off telephone5. Write an invoice

Scenario of Receptionist(Use case description)

<<human>>

Context diagramHome deliverypizza

Receive orders

Deliver pizzas

Get payment

Goal model

Step 2: Identify Problemsl In the integrated model, find problems:l E.g.,– High human workload– Complex work

l Identify the source goal(s)

Constructa model

Refinegoals

Identifyproblems

Notfound

Step 2. Identify Problems

Staff (S)

Customer (C)

C! Order

<<human>>

Context diagramHome deliverypizza

Receive orders

Deliver pizzas

Get payment

Goal model

Many shared events btw. Staff and Customer

= High human workload

Step 3: Refine Goalsl For the problematic goals in As-is by– Refining them– Defining their alternatives

Constructa model

Refinegoals

Identifyproblems

Notfound

As-is goal model To-be goal model

Refine

Store andupdate customers’

information

Retrieve customers’ information

Reduce staffs’ effortsin getting name, telephone number,

address from a customer

Record and utilizecustomers’ information

ordered before

Receive ordersby fax

Home deliverypizza

Receive orders

Can order with anequipment anyone has

Easy to orderfor customers

Deliver pizzas

Step 4: Construct To-bel Constructs an integrated model– From new To-be goal model

l Iterative process– Identifies problems again– Stops if no problems found

Constructa model

Refinegoals

Identifyproblems

Notfound

To-be goal model

Staff (S)

Customer (C)

C! Order

C! Telephone number

Retrieve

Update

1. Pick up telephone2. (Get) Telephone number3. Retrieve4. (Get) Order5. Ring off telephone6. Write an invoice

Customer ManagementSystem (CM)

S! Retrieve

Reduce staffs’ effortsin getting name, telephone number,

address from a customer

Record and utilizecustomers’ information

ordered before

Store andupdate customers’

information

Retrieve customers’information

includes

<<human>>

To-be Integrated Model

Metric-Based Identification

Constructa model

Refinegoals

Identifyproblems

Notfound

[1] Basili, V., Caldiera, C. and Rombach, D.: Goal, Question, Metric Paradigm, Encyclopedia of Software Engineering, Vol.1, pp.528–532, 1994.

Use of GQM [1]

A framework to find useful metricsby deriving• Questions from Goals• Metris from Questions

Approach: Quantifying it via metrics

Aim: (semi-)automatedidentification of problems

Applying GQM

Identifying the locations toautomate/reduce human efforts

Which was frequently performed by human?

Which was hardfor human?

Question

In which was many kinds

of human work performed?

In which was human work preformed at many times?

Which workwas complex for human?

Which work was time

consuming for human?

NE ANOSACCCE

Metric

CE (Count of Events)# distinct events related to each human domain

Staff (S)

Customer (C)

Invoice (I)

S! Write an invoice

C! Order

<<human>>

Context diagramCE(Staff) = 5

NE (Number of Events)

Staff (S)

Customer (C)

Invoice (I)

S! Write an invoice

C! Order

<<human>>

Context diagramNE(Staff) = 5

# event occurrences on each human domain

ACC and ANOSl ACC (Actor-related Cyclomatic Complexity)– CC in UCD [5], limited to human-related steps– # alternative flows + 1

l ANOS (Actor-related Number of Steps)– # human-related steps in UCD

Use case 1: Receive orders by telephonePrecondition: Telephone ringingBasic flow:

ACC(UC1) = 1ANOS(UC1) = 5

Supporting Tool

Integrated Model

Use case descriptioneditor Context diagram

editor

Goal model editor

Illustrative ExampleReporting operation of a brokerage office

Brokerageanalyst

Dedicatedterminal

Historyserver

Distributionserver

Personalterminal

Upload report filesin PDF format

Downloadpast reports

Download/Upload

Write reports

Upload reports

Step 1: As-Is Model

UC1 Collect data

Basic flow1. Call UC32. ......3. ......

Post-condition: Brokerage information provided

Goal model(12 goals)

Context diagram(6 domains, 16 events)

Reporting operationof a brokerage office

Create a report Manage reports

UC1: Collect data UC2: Write a report

UC7: Fix a reportin the distribution server

UC3: Fetch a report

UC5: Store a reportto the distribution server

UC4: Store a reportto the history server

UC6: Fix a reportin the history server

Fix a report Store a report

Use case descriptions(7 use cases)

Info. Source

Analyst

Dedicated Terminal History Server

A! Survey (1.2)

A! Translate (4.1)

A! Upload (4.2)

T! SendPDF (4.3)

T! SendReport (5.1)IS! ProvideInfo (1.3)

PersonalTerminal

Distribution Server

A! OpenReport (2.1, 7.1, 6.1)A! ModifyReport (7.2, 6.2)

A! RequestReport (3.1)A! Upload (5.2)

PT! SendReport (5.3)PT! RequestReport (3.2)HS! SendReport (3.3)

PT! SendReport (3.4)

A! CreateReport (2.2)

A! SendReport (3.5)

<<human>>

UC3: Fetch a report

Goal Model (As-is)

Info. Source

Analyst

A! Survey (1.2)

A! Translate (4.1)

A! Upload (4.2)

T! SendPDF (4.3)

PersonalTerminal

Distribution Server

A! SendReport (3.5)

<<human>>

UC1 Collect data

Step 2: Identify Problemsl Calculating metric values and detecting problems

Use cases ANOS ACCUC1 5 1UC2 2 1UC3 3 1UC4 2 1UC5 2 1UC6 7 2UC7 7 2

Events on Analyst #A! RequestReport 1A! Upload 2A! SendReport 2A! Translate 1A! OpenReport 3A! ModifyReport 2A! CreateReport 1A! Survey 1PT! SendReport 1IS! ProvideInfo 1

Total (NE) 15

CE= 12

Context Diagram (As-is)

Info. Source

Analyst

A! Survey (1.2)

A! Translate (4.1)

A! Upload (4.2)

T! SendPDF (4.3)

PersonalTerminal

Distribution Server

A! SendReport (3.5)

<<human>>

Use Case Desc. (As-is)ACC(UC6) = 2ANOS(UC6) = 7

UC7: Fix a reportin the distribution

server

UC3: Fetch a report

Goal Model (As-is)

Step 3: Refine Goals(Build Solution)

Goal Model (As-is)

Report managementsystem

Manage reports(w/ USB)

Manage reports

alternative

Create a reportManage reports

UC3: Fetch a report

Create a report Report management

systemUC1: Collect data UC2: Write a report

UC3': Fetch a reportUC6-7: Fix a reportUC4-5:

Store a report

Goal Model (To-be)

Create a reportReport management

system

UC3': Fetch a report

UC6-7: Fix a reportUC4-5:

Store a report

Goal Model (To-be)

Step 4: To-be Model

Goal model(8 goals)

Info. Source

Analyst

History Server

A! Survey (1.3)MS! Translate (4-5.4)

A! Upload (4-5.1)

MS! SendPDF (4-5.5)

MS! SendReport (4-5.3)

IS! ProvideInfo (1.4)

PersonalTerminal

Distribution Server

A! OpenReport (2.1, 6-7.1)A! ModifyReport (6-7.2)

HS! SendReport (3'.4)

Management System

A! RequestReport (3'.1)

T! RequestReport (3'.2)

MS! RequestReport (3'.3)MS! SendReport (3'.5)

T! SendReport (4-5.2)<<human>>

Create a reportReport

managementsystem

Store a report

UC1 Collect data

Info. Source

Analyst

History Server

A! Upload (4-5.1)

MS! SendPDF (4-5.5)

PersonalTerminal

Distribution Server

A! OpenReport (2.1, 6-7.1)

A! ModifyReport (6-7.2)HS! SendReport (3'.4)

Management System

T! SendReport (4-5.2)

<<human>>

Context Diagram (To-be)l ΔCE = CETo-be – CEAs-is = 7 – 12 = –5 l ΔNE = NETo-be – NEAs-is = 8 – 15 = –7

Reduced!

Use Case Desc. (To-be)

ACC(UC3) = 1ANOS(UC3) = 3

ACC(UC3') = 1ANOS(UC3') = 1

l ΔACC = ACCTo-be – ACCAs-is = 1 – 1 = 0l ΔANOS = ANOSTo-be – ANOSAs-is = 1 – 3 = –2

Reduced!

Summary of Applicationl It could show that …– Our technique could find problems in As-is model– The effectiveness of model updates from As-is to To-be

Step 1: As-Is Model

UC1 Collect data

Goal model(12 goals)

UC3: Fetch a report

Info. Source

Analyst

A! Survey (1.2)

A! Translate (4.1)

A! Upload (4.2)

T! SendPDF (4.3)

PersonalTerminal

Distribution Server

A! SendReport (3.5)

<<human>>

Step 4: To-be Model

Goal model(8 goals)

Info. Source

Analyst

History Server

A! Upload (4-5.1)

MS! SendPDF (4-5.5)

PersonalTerminal

Distribution Server

A! OpenReport (2.1, 6-7.1)A! ModifyReport (6-7.2)

HS! SendReport (3'.4)

Management System

T! SendReport (4-5.2)<<human>>

Create a reportReport

managementsystem

Store a report

UC1 Collect data

Future Workl Case study++l Deriving more metrics to extract more

problems– Different focus: skills or health conditions of human– Make guidelines how to construct GQM trees– Make reusable catalogs of metrics

l Automated transformation from As-is to To-be models – Define evolution patterns as model transformations

ConclusionOur Solution:

GORA: Goal model

Problem Frame: Context diag.

For understanding systems’ behaviorClarifies the boundary between

machines and environments

LightsController

LightUnits(LU)

LightCycle

2 .2 .

Integrated Model

Use case modeling: Use case descriptionProvides sequence of steps of each functionalitywhich can be a glue to connect two modeling techniques

Identify problems in an integrated model w/ metrics via GQMConstructa model

Constructa model

Refinegoals

Identifyproblemsfound

Notfound

Our Approach

l 4 steps incl. iteration1. Construct an As-is model2. Identify its problems3. Refine goals4. Construct a To-be model

NE ANOSACC

Identifying the locations toautomate/reduce human efforts

Which was frequently performed by human?

Which was hardfor human?

In which was many kinds

of human work performed?

In which was human work preformed at many times?

Which workwas complex for human?

Which work was time

consuming for human?

Applying GQMGoal

Question

Metric

Step 3: Refine Goals(Build Solution)

Goal Model (As-is)

Report managementsystem

Manage reports(w/ USB)

Manage reports

alternative

Create a reportManage reports

UC3: Fetch a report

Create a report Report management

systemUC1: Collect data UC2: Write a report

Store a report

Goal Model (To-be)