Lean Architecture

More and more Agile projects are seeking architectural roots as
they struggle with complexity and scale - and they're seeking
lightweight ways to do it

• Still seeking? In this book the authors help
  you to find your own path

• Taking cues from Lean development, they can help steer
  your project toward practices with longstanding track records

• Up-front architecture? Sure. You can deliver an
  architecture as code that compiles and that concretely guides
  development without bogging it down in a mass of documents and
  guesses about the implementation

• Documentation? Even a whiteboard diagram, or a CRC card,
  is documentation: the goal isn't to avoid documentation, but to
  document just the right things in just the right amount

• Process? This all works within the frameworks of Scrum,
  XP, and other Agile approaches

Autorentext
James O. Coplien is a writer, lecturer, and researcher in the field of Computer Science. He has made key contributions in the areas of software design and organizational development, software debugging, and in empirical research. His early work on C++ idioms was one of the three primary sources of the popular Design Patterns. His work on Organizational patterns was an inspiration for both Extreme Programming and for Scrum. Cope was a founding Member of Hillside Group with Kent Beck, Grady Booch, Ward Cunningham, Ralph Johnson, Ken Auer and Hal Hildebrand. He is responsible for starting up several of the conferences in the Pattern Languages of Programming (PLoP) conference series and is a longstanding pattern author and PLoP shepherd. Gertrud Bjornvig is an experienced software consultant and trainer and has been in software development since 1984. She's been working on development teams as a developer, analyst, and project manager, and has had cross-organizational roles as methodologist and process consultant. Her background is in object-oriented development, including extensive work with UML and RUP. Gertrud has been employed by Enator, Navision, Microsoft, and TietoEnator, but since June 2007 she has been independent as a part of Gertrud & Cope.
Gertrud holds a Master in Computer Science and Communication and is one of the founders of Danish Agile User Group.

Klappentext
It's time for change - after 30 years, DCI has risen to complete the vision of object-oriented programming! Aiming at no less than a paradigm shift, Lean Architecture uses a modern approach to software design, while embracing refreshing new insights of Lean and Agile. Giving a down-to-earth view of Agile requirements and the often-ignored relationship between requirements and architecture, this book goes beyond the fashionable idea of User Stories, and shows you how to employ Use Cases in a lightweight, incremental, Agile way. The authors detail the DCI (Data, Context and Interaction) architecture paradigm and show how DCI succeeds where object-oriented programming languages alone have failed to integrate software design with the end user's understanding of the overall business structure.

However, this is not a methodology book, but a book which focuses on code, with plenty of code examples. Topics covered include: Agile production, Stakeholder Engagement, Organizational issues, Scala/Python/Java implementation of the DCI account example, Qi4J and much more.

Renowned software architecture expert James Coplien and agile requirements expert Gertrud Bjørnvig share their expertise to give you concrete design advice that will help you:

• Create software that builds on your end-user mental models rather than design methodologies
• Write software that can directly be verified against behavioral requirements
• Organize - so that all your stakeholders support each other
• Support rapidly changing feature code in stable domain code to help embrace change
  Lean Architecture casts a new light over important aspects of software development that have been marginalized or forgotten by the agile movement it will help you find your own path.

Zusammenfassung
More and more Agile projects are seeking architectural roots as they struggle with complexity and scale - and they're seeking lightweight ways to do it

• Still seeking? In this book the authors help you to find your own path
• Taking cues from Lean development, they can help steer your project toward practices with longstanding track records
• Up-front architecture? Sure. You can deliver an architecture as code that compiles and that concretely guides development without bogging it down in a mass of documents and guesses about the implementation
• Documentation? Even a whiteboard diagram, or a CRC card, is documentation: the goal isn't to avoid documentation, but to document just the right things in just the right amount
• Process? This all works within the frameworks of Scrum, XP, and other Agile approaches

Inhalt

About the Authors xii

Preface xiii

1 Introduction 1

1.1 The Touchstones: Lean and Agile 1

1.2 Lean Architecture and Agile Feature Development 4

1.3 Agile Production 7

1.3.1 Agile Builds on Lean 7

1.3.2 The Scope of Agile Systems 8

1.3.3 Agile and DCI 9

1.4 The Book in a Very Small Nutshell 10

1.5 Lean and Agile: Contrasting and Complementary 11

1.5.1 The Lean Secret 14

1.6 Lost Practices 14

1.6.1 Architecture 15

1.6.2 Handling Dependencies between Requirements 15

1.6.3 Foundations for Usability 16

1.6.4 Documentation 16

Code Does Not Stand Alone 17

Capturing the ''Why'' 19

1.6.5 Common Sense, Thinking, and Caring 19

1.7 What this Book is Not About 21

1.8 Agile, Lean Oh, Yeah, and Scrum and Methodologies and Such 22

1.9 History and Such 24

2 Agile Production in a Nutshell 27

2.1 Engage the Stakeholders 27

2.2 Define the Problem 29

2.3 Focusing on What the System Is: The Foundations of Form 30

2.4 Focusing on What the System Does: The System Lifeblood 32

2.5 Design and Code 33

2.6 Countdown: 3, 2, 1. . . 34

3 Stakeholder Engagement 35

3.1 The Value Stream 35

3.1.1 End Users and Other Stakeholders as Value Stream Anchors 36

3.1.2 Architecture in the Value Stream 37

3.1.3 The Lean Secret 38

3.2 The Key Stakeholders 41

3.2.1 End Users 43

Psyching Out the End Users 44

Don't Forget Behavior 46

The End User Landscape 47

3.2.2 The Business 47

A Special Note for Managers 48

3.2.3 Customers 50

. . . As Contrasted with End Users 50

''Customers'' in the Value Stream 52

3.2.4 Domain Experts 52

No Ivory Tower Architects 53

Experts in Both Problemand Solution Domains 54

3.2.5 Developers and Testers 55

3.3 Process Elements of Stakeholder Engagement 57

3.3.1 Getting Started 58

3.3.2 Customer Engagement 60

3.4 The Network of Stakeholders: Trimming Wasted Time 61

3.4.1 Stovepipe Versus Swarm 61

3.4.2 The First Thing You Build 64

3.4.3 Keep the Team Together 65

3.5 No Quick Fixes, but Some Hope 66

4 Problem Definition 67

4.1 What's Agile about Problem Definitions? 68

4.2 What's Lean about Problem Definitions? 68

4.3 Good and Bad Problem Definitions 70

4.4 Problems and Solutions 72

4.5 The Process Around Problem Definitions 73

4.5.1 Value the Hunt Over the Prize 73

4.5.2 Problem Ownership 74

4.5.3 Creeping Featurism 75

4.6 Problem Definitions, Goals, Charters, Visions, and Objectives 76

4.7 Documentation? 77

5 What the System Is, Part 1: Lean Architecture 79

5.1 Some Surprises about Architecture 80

5.1.1 What's Lean about This? 82

Deliberation and ''Pull'' 83

Failure-Proof Constraints or Poka-Yoke 83

The Lean Mantras of Conservation, Consistency, and Focus 84

5.1.2 What's Agile about Architecture? 84

It's All About Individuals and Interactions 84

Past Excesses 85

Dispelling a Couple of Agile Myths 86 …