®
IBM Software Group
Ivar Jacobson
IBM Rational ivar@rational.com
Jaczone AB ivar@jaczone.com

IBM Software Group | Rational software
Agenda
 The Ericsson Success Story
 Use Cases
 System of Systems

IBM Software Group | Rational software
The Ericsson Success Story
 What we can’t learn from a 30 year old case story
 Layered architecture – we had two layers only
 Middle-ware and system-ware
– only system-ware
 Software tools
– there was only an IDE
 What we can we learn from it
 What development processes to employ
•
Software
•
Software+Hardware+Peopleware
 What modeling language to use
 Systems of Systems
 Transitioning to a reuse business
•
Reengineering of organization

IBM Software Group | Rational software
Lessons learnt – Software Process
Development approach was
 Component-based
 Requirements-driven
 Architecture-centric
 Visual Modeling
 Configuration management
Today we would request process to also be
 Use-case driven
 Iterative & incremental
 Risk-driven
 Verify & validate from the beginning
 Tool supported
 Etc.

IBM Software Group | Rational software
Lessons learnt -- Modeling language
A first generation modeling language
 Block diagrams
 Sequence diagrams
 Collaboration diagrams
 State transistion diagrams with activity diagrams
 Activity diagrams with swimlanes
These ideas are now in SDL and UML. But no tools were used!
Today we have tools – lifecycle point tools and cross-lifecycle tools

IBM Software Group | Rational software
Block diagram (component diagrams)
Feb 1968

IBM Software Group | Rational software
Sequence diagrams
!970-06-25

IBM Software Group | Rational software
Agenda
 The Ericsson Success Story
 Use Cases
 System of Systems

IBM Software Group | Rational software
Use Cases are part of a LifeCycle Process
The Unified Process
 It is the UML process
 It is component-based
 It is
 Use-case driven
 Architecture-centric
 Iterative and incremental
 Configurable

IBM Software Group | Rational software
Use Cases Capture Requirements
A use case is a sequence of actions a system performs that yields an observable result of value to a particular actor
 Use cases reside inside the system
 A use case describes the actions the system takes to deliver to the actor
 Taken together, all use cases constitute all ways of using the system
Bank customer
Withdraw money
Actor Use Case

IBM Software Group | Rational software
Use cases are identified in Requirements
 FURPS
 Functionality
 Usability
 Reliability
 Performance
 Supportability
}  Design Constraints
 Operating systems
 Environments
 Compatibility
 Application standards

IBM Software Group | Rational software
Use Case Driven Development
 Any product development should follow three steps:
 Capture the users ’ needs
 Design to fit those needs
}
 Test that the needs are fulfilled
Req’t Design & Impl.
Test
Capture the Use Cases
Design to
Implement the Use Cases
Test that the
Use Cases are Fulfilled

IBM Software Group | Rational software
Requirements: Capture the use cases
 A use case model
ATM
Withdraw Money
Deposit Money
Bank
Customer
Transfer Between Accounts
Bank
System

IBM Software Group | Rational software
Use cases versus traditional feature spec’s?
 A feature specification attempts to reply to the question:
“What is the system supposed to do?”
 The use case strategy forces us to add three words to the end of that question: “… for each user?”

IBM Software Group | Rational software
Design & Implementation: use case design
 Use cases are eventually realized as components
ATM
Withdraw Money
Deposit Money
Bank
Customer
Transfer Between Accounts
Bank
System
Withdrawal
Components
Cash

IBM Software Group | Rational software
Use cases – use case realizations -- components
 Each use case is realized by a collaboration - a set of classes
 A class plays different roles in different use case realizations
 The total responsibility of a class is the composition of these roles
Use case
Specification
Use case design
Component design & implementation
Withdraw Cash
Transfer Funds
Deposit Funds
Interface Cash
Withdrawal
Cash
Interface Transfer
Funds
Interface Deposit
Funds
Cash
Cash
Withdrawal
Interface Transfer
Funds
Deposit
Funds
Cash

IBM Software Group | Rational software
Test: use case tests
ATM
Withdraw Money
Deposit Money
Bank
Customer
Transfer Between Accounts
Bank
System
Test Cases
 Use Case Modeling Done!

Design Done!


Use Case Scenarios
Cash Withdrawal of a pre-set amount
Cash Withdrawal of custom amount
Etc.
Many Test Cases for every Use Case
Plan Testing & Define
Test Cases
Generate Test Cases
From Sequence diagrams and State-Chart diagrams
 Basis for the Test Specification

IBM Software Group | Rational software
Identifying Use Case Scenarios
Use Case: Withdraw Money
Valid Card Invalid Card
Amount
Invalid
Valid PIN Code Invalid PIN Code
. . .
Amount
> Daily Limit
Amount
> Account Balance
Amount
Valid and in Range

IBM Software Group | Rational software
The Role of Use Cases
Requirements
Architecture
Iteration
Planning
Use
Cases
Business
Modeling
User Experience
Test
Design
Analysis &
Design

IBM Software Group | Rational software
UCD
Req’t Design & Impl.
Test
Analyze: Design
:
Test
:
Use Cases are the glue that binds

IBM Software Group | Rational software
Agenda
 The Ericsson Success Story
 Use Cases
 System of Systems

IBM Software Group | Rational software
System of Interconnected Systems
 Use case of the superordinate system is realized by use cases of the subordinate systems
 Superordinate use cases and subordinate use cases

IBM Software Group | Rational software
Common Development Concerns
 Enterprise architecting
 Defining an architecture that underpins a number of systems
 Strategic reuse
 Developing reusable assets that are used within a number of systems
 Systems engineering
 Developing a system that contains elements of hardware, software, workers and data
 Enterprise Application Integration
 Developing a solution that includes the integration of a number of legacy systems
 Packaged application development
 Developing a solution that includes the configuration of a packaged application, such as an ERP or CRM solution
 Outsourced development
 Defining an architecture that lends itself to the outsourced development of its constituent parts, whilst ensuring the quality and integrity of these parts

IBM Software Group | Rational software
What is a System?
 UML
 A system is a top-level subsystem in a model. A subsystem is a grouping of model elements that represents a behavioral unit in a physical system.
A subsystem offers interfaces and has operations. In addition, the model elements of a subsystem can be partitioned into specification and realization elements.
 RUP
 A system is a collection of connected units that are organized to accomplish a specific purpose. A system can be described by one or more models, possibly from different viewpoints.
 RUP-SE
 A system provides a set of services that are used by an enterprise to carry out a business purpose. System components typically consist of hardware, software, data, and workers.

IBM Software Group | Rational software
Applying Systems of systems
 Enterprise Architecting
 The decomposition of an enterprise into its respective elements can be expressed in terms of a “system of systems”
 Strategic Reuse
 Reusable assets and their relationships can be described in terms of a
“system of systems”
 Systems Engineering
 The system as a whole can be expressed in terms of a superordinate system, and each of the elements that comprise the system can be expressed in terms of a subordinate system
 Enterprise Application Integration
 The context within which a legacy system fits can be described in terms of a superordinate system, with the legacy system itself represented as a subordinate system
 Packaged Application Development
 The packaged application may represent a subordinate system (if it is a
“piece”) or a superordinate system (if it is a “whole”)
 Outsourced Development
 The overall architecture can be described in terms of a superordinate system, with the constituent parts described in terms of subordinate systems

IBM Software Group | Rational software
Rounding Up
 From a Swedish Perspective
 TBD

IBM Software Group | Rational software
For More Information
 www.rational.com
 The UML Books
( Booch, Jacobson, Rumbaugh with Addison Wesley )
 The UML User Guide
 The UML Reference Manual
 The Unified Software Development Process

IBM Software Group | Rational software
Other Readings by Ivar Jacobson
 Object-Oriented Software Development--A Use Case Driven Approach
(Addison Wesley)
Jacobson et al, Addison Wesley Longman (1992)
 The Object Advantage: Business Process Reengineering with Objects
(Addison Wesley)
Jacobson et al, Addison Wesley Longman (1994)
 Software Reuse: Architecture, Process and Organization for Business
Success (Addison Wesley)
Ivar Jacobson, Martin Griss & Patrik Jonsson, Addison Wesley Longman
(1997)
 The Unified Software Development Process
Jacobson, Booch, Rumbaugh, Addison Wesley Longman (1999)
 The Road to the Unified Software Development Process
Ivar Jacobson, Stefan Bylund, Cambridge University Press, 2000
 Aspect-Oriented Software Development with Use Cases
Ivar Jacobson, Pan Wei Ng, 2004, NEW