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Requirements and Incremental Design 1 [email protected] 2.11.1999
Contents
How do requirements behave today?
CMM - Capability Maturity Model - Req. Mgmt
The Incremental Development Model
Johan SjöblomProduct Area Manager
Ericsson [email protected]
Requirements and Incremental Design 2 [email protected] 2.11.1999
How Do Requirements Behave Today?
Requirements Loosen Up when moving from networks to services and applications
Requirements and Incremental Design 3 [email protected] 2.11.1999
Requirements without 50k of ITU/ETSI specs?
No Microsoft type player around in Telecom??
Industry Consortiums:– Symbian, EPOC operating system, www.symbian.com– WAP Forum, www.wapforum.org– Bluetooth
Other de facto standards– IETF: Req. For Comments (RFC’s)– Java API’s– W3C (HTML, XHTML, XML)
Requirements and Incremental Design 4 [email protected] 2.11.1999
CMM & Requirement Management
CMM - Capability Maturity Model
Levels 1-5
Level 2 is project oriented, and is called “repeatable”
KPA - Key Process Areas
Requirement Management is a KPA in CMM level 2
Requirements and Incremental Design 5 [email protected] 2.11.1999
CMM 2 - KPA - RM - Activity 1
The software engineering group reviews the allocated requirements BEFORE they are incorporated into the software project
– 4. Commitments resulting from the allocated requirements are negotiated with the affected groups.
Requirements and Incremental Design 6 [email protected] 2.11.1999
CMM 2 - KPA - RM - Activity 2
The software engineering group uses the allocated requirements as the basis for software plans, work products, and activities.
– 1. Allocated requirements are managed and controlled.
Requirements and Incremental Design 7 [email protected] 2.11.1999
CMM 2 - KPA - RM - Activity 3
Changes to the allocated requirements are reviewed and incorporated into the software project
– 1. The impact to existing commitments is assessed, and changes are negotiated as appropriate.
Requirements and Incremental Design 9 [email protected] 2.11.1999
Introduction to Incremental Development
Part I • Waterfall model• Problems with the waterfall model• Incremental Development concepts
Part II• Incremental Development: Benefits, Pitfalls & Concerns• Experiences
Requirements and Incremental Design 10 [email protected] 2.11.1999
Waterfall model
Analysis Implementation Test
time
Requirements and Incremental Design 11 [email protected] 2.11.1999
Existing Problems (1)
• Late feedback for customers and designers• How to cope with changing requirements?• Big bang integration with interface and integration
problems
Big Bang Integration
Requirements and Incremental Design 12 [email protected] 2.11.1999
Existing problems (2)
• Rush on test resources• Lack of Project Control• Slow process improvement
“Rush on test resources”
Requirements and Incremental Design 13 [email protected] 2.11.1999
ID Process View
* Divide the work in small controllable parts (= increments)
* Increments must be testable parts of the system
Analysis Implementation TestPlan Integrate
Plan
Integrate
Requirements and Incremental Design 14 [email protected] 2.11.1999
ID System View
1246 3 5 7
Each accumulation of developed increments isa complete user executable system
User Functionality
Platform
Requirements and Incremental Design 16 [email protected] 2.11.1999
Benefits
Implementation TestAnalysiswaterfall
incremental
Analysis
ImplementationTest
1) Lead-time reduction
Requirements and Incremental Design 17 [email protected] 2.11.1999
Benefits
2) No ‘big bang’ integration
Waterfall
Incremental Development
IntegrateTime to solve problems
Integrate Integrate Integrate
Requirements and Incremental Design 18 [email protected] 2.11.1999
Benefits
3) Handling of unstable requirements
Unstable requirement
Added requirement
Requirements and Incremental Design 19 [email protected] 2.11.1999
Pitfalls1) Planning & Tracking
Charging SW Superv.
HW Superv.
HW Init.
Statistics
Traffic
Load appl.
Load OS
Commands
• Allocation of features dependent of technical contents.• Delay in one part of the project can on short term impact early deliveries.
Planning
Anatomy
Requirements and Incremental Design 20 [email protected] 2.11.1999
Pitfalls
project X
product baseline
project Y
incr. 1
2) Configuration Management
incr. 1
incr. 1
Requirements and Incremental Design 21 [email protected] 2.11.1999
Pitfalls
3) Postponement of features
Requirements and Incremental Design 22 [email protected] 2.11.1999
Concerns
More increments implies shorter design - verification cycles
Extra testing– Test cases needs to be rerun in several increments– Possibility for continues system test
More reviews and inspections– Documents impacted by several increments need more
inspections. (simplyfied inspections from R&I)
4
Requirements and Incremental Design 23 [email protected] 2.11.1999
ConclusionID solves the following problems in waterfall
projects:– Late feedback / Changing requirements / Big bang
integration– Rush on test resources / Lack of project control / Slow
process improvement
Is has been used successfully for the last decade
Extra attention needed for:– Planning & Tracking– Configuration Management
Increased use of testing and reviews & inspections
