SOA服务设计原则

Preface

Chapter 1:Introduction

1.1 Objectives of this Book

1.2 Who this Book Is For

1.3 What this Book Does Not Cover

Topics Covered by Other Books

SOA Standardization Efforts

1.4 How this Book Is Organized

Part I:Fundamentals

Part II:Design Principles

Part III:Supplemental

Appendices

1.5 Symbols,Figures,and Style Conventions

Symbol Legend

How Color Is Used

The Service Symbol

1.6 Additional Information

Updates,Errata,and Resources(www.soabooks.com)

Master Glossary(www.soaglossary.com)

Referenced Specifications(www.soaspecs.com)

Service-Oriented Computing Poster(www.soaposters.com)

The SOA Magazine(www.soamag.com)

Notification Service

Contact the Author

Chapter 2:Case Study

2.1 Case Study Background:Cutit Saws Ltd

History

Technical Infrastructure and Automation Environment

Business Goals and Obstacles

PART I:FUNDAMENTALS

Chapter 3:Service-Oriented Computing and SOA

3.1 Design Fundamentals

Design Characteristic

Design Principle

Design Paradigm

Design Pattern

Design Pattern Language

Design Standard

Best Practice

A Fundamental Design Framework

3.2 Introduction to Service-Oriented Computing

Service-Oriented Architecture

Service-Orientation,Services,and Service-Oriented Solution Logic

Service Compositions

Service Inventory

Understanding Service-Oriented Computing Elements

Service Models

SOA and Web Services

Service Inventory Blueprints

Service-Oriented Analysis and Service Modeling

Service-Oriented Design

Service-Oriented Architecture:Concepts,Technology,and Design

3.3 Goals and Benefits of Service-Oriented Computing

Increased Intrinsic Interoperability

Increased Federation

Increased Vendor Diversification Options

Increased Business and Technology Domain Alignment

Increased ROI

Increased Organizational Agility

Reduced IT Burden

3.4 Case Study Background

Chapter 4:Service-Orientation

4.1 Introduction to Service-Orientation

Services in Business Automation

Services Are Collections of Capabilities

Service-Orientation as a Design Paradigm

Service-Orientation and Interoperability

4.2 Problems Solved by Service-Orientation

Life Before Service-Orientation

The Need for Service-Orientation

4.3 Challenges Introduced by Service-Orientation

Design Complexity

The Need for Design Standards

Top-Down Requirements

Counter-Agile Service Delivery in Support of Agile Solution Delivery

Governance Demands

4.4 Additional Considerations

It Is Not a Revolutionary Paradigm

Enterprise-wide Standardization Is Not Required

Reuse Is Not an Absolute Requirement

4.5 Effects of Service-Orientation on the Enterprise

Service-Orientation and the Concept of""Application""

Service-Orientation and the Concept of""Integration""

The Service Composition

Application,Integration,and Enterprise Architectures

4.6 Origins and Influences of Service-Orientation

Object-Orientation

Web Services

Business Process Management(BPM)

Enterprise Application Integration(EAI)

Aspect-Oriented Programming(AOP)

4.7 Case Study Background

Chapter 5:Understanding Design Principles

5.1 Using Design Principles

Incorporate Principles within Service-Oriented Analysis

Incorporate Principles within Formal Design Processes

Establish Supporting Design Standards

Apply Principles to a Feasible Extent

5.2 Principle Profiles

5.3 Design Pattern References

5.4 Principles that Implement vs.Principles that Regulate

5.5 Principles and Service Implementation Mediums

""Capability""vs.""Operation""vs.""Method""

5.6 Principles and Design Granularity

Service Granularity

Capability Granularity

Data Granularity

Constraint Granularity

Sections on Granularity Levels

5.7 Case Study Background

The Lab Project Business Process

PART II:DESIGN PRINCIPLES

Chapter 6:Service Contracts(Standardization and Design)

6.1 Contracts Explained

Technical Contracts in Abstract

Origins of Service Contracts

6.2 Profiling this Principle

6.3 Types of Service Contract Standardization

Standardization of Functional Service Expression

Standardization of Service Data Representation

Standardization of Service Policies

6.4 Contracts and Service Design

Data Representation Standardization and Transformation Avoidance

Standardization and Granularity

Standardized Service Contracts and Service Models

How Standardized Service Contract Design Affects Other Principles

6.5 Risks Associated with Service Contract Design

Versioning

Technology Dependencies

Development Tool Deficiencies

6.6 More About Service Contracts

Non-Technical Service Contract Documents

Web Service Contract Design for SOA

6.7 Case Study Example

Planned Services

Design Standards

Standardized WSDL Definition Profiles

Standardized XML Schema Definitions

Standardized Service and Data Representation Layers

Service Descriptions

Conclusion

Chapter 7:Service Coupling(Intra-Service and Consumer Dependencies)

7.1 Coupling Explained

Coupling in Abstract

Origins of Software Coupling

7.2 Profiling this Principle

7.3 Service Contract Coupling Types

Logic-to-Contract Coupling(the coupling of service logic to the service contract)

Contract-to-Logic Coupling(the coupling of the service contract to its logic)

Contract-to-Technology Coupling(the coupling of the service contract to its underlying technology)

Contract-to-Implementation Coupling(the coupling of the service contract to its implementation environment)

Contract-to-Functional Coupling(the coupling of the service contract to external logic)

7.4 Service Consumer Coupling Types

Consumer-to-Implementation Coupling

Standardized Service Coupling and Contract Centralization

Consumer-to-Contract Coupling

Measuring Consumer Coupling

7.5 Service Loose Coupling and Service Design

Coupling and Service-Orientation

Service Loose Coupling and Granularity

Coupling and Service Models

How Service Loose Coupling Affects Other Principles

7.6 Risks Associated with Service Loose Coupling

Limitations of Logic-to-Contract Coupling

Problems when Schema Coupling Is""too loose""

7.7 Case Study Example

Coupling Levels of Existing Services

Introducing the InvLegacyAPI Service

Service Design Options

Chapter 8:Service Abstraction(Information Hiding and Meta Abstraction Types)

8.1 Abstraction Explained

Origins of Information Hiding

8.2 Profiling this Principle

Why Service Abstraction Is Needed

8.3 Types of Meta Abstraction

Technology Information Abstraction

Functional Abstraction

Programmatic Logic Abstraction

Quality of Service Abstraction

Meta Abstraction Types and the Web Service Regions of Influence

Meta Abstraction Types in the Real World

8.4 Measuring Service Abstraction

Contract Content Abstraction Levels

Access Control Levels

Abstraction Levels and Quality of Service Meta Information

8.5 Service Abstraction and Service Design

Service Abstraction vs.Service Encapsulation

How Encapsulation Can Affect Abstraction

Service Abstraction and Non-Technical Contract Documents

Service Abstraction and Granularity

Service Abstraction and Service Models

How Service Abstraction Affects Other Principles

8.6 Risks Associated with Service Abstraction

Multi-Consumer Coupling Requirements

Misjudgment by Humans

Security and Privacy Concerns

8.7 Case Study Example

Service Abstraction Levels

Operation-Level Abstraction Examples

Chapter 9:Service Reusability(Commercial and Agnostic Design)

9.1 Reuse Explained

Reuse in Abstract

Origins of Reuse

9.2 Profiling this Principle

9.3 Measuring Service Reusability and Applying Commercial Design

Commercial Design Considerations

Measures of Planned Reuse

Measuring Actual Reuse

Commercial Design Versus Gold-Plating

9.4 Service Reuse in SOA

Reuse and the Agnostic Service

The Service Inventory Blueprint

9.5 Standardized Service Reuse and Logic Centralization

Understanding Logic Centralization

Logic Centralization as an Enterprise Standard

Logic Centralization and Contract Centralization

Centralization and Web Services

Challenges to Achieving Logic Centralization

9.6 Service Reusability and Service Design

Service Reusability and Service Modeling

Service Reusability and Granularity

Service Reusability and Service Models

How Service Reusability Affects Other Principles

9.7 Risks Associated with Service Reusability and Commercial Design

Cultural Concerns

Governance Concerns

Reliability Concerns

Security Concerns

Commercial Design Requirement Concerns

Agile Delivery Concerns

9.8 Case Study Example

The Inventory Service Profile

Assessing Current Capabilities

Modeling for a Targeted Measure of Reusability

The New EditItemRecord Operation

The New ReportStockLevels Operation

The New AdjustItemsQuantity Operation

Revised Inventory Service Profile

Chapter 10:Service Autonomy(Processing Boundaries and Control)

10.1 Autonomy Explained

Autonomy in Abstract

Origins of Autonomy

10.2 Profiling this Principle

10.3 Types of Service Autonomy

Runtime Autonomy(execution)

Design-Time Autonomy(governance)

10.4 Measuring Service Autonomy

Service Contract Autonomy(services with normalized contracts)

Shared Autonomy

Service Logic Autonomy(partially isolated services)

Pure Autonomy(isolated services)

Services with Mixed Autonomy

10.5 Autonomy and Service Design

Service Autonomy and Service Modeling

Service Autonomy and Granularity

Service Autonomy and Service Models

How Service Autonomy Affects Other Principles

10.6 Risks Associated with Service Autonomy

Misjudging the Service Scope

Wrapper Services and Legacy Logic Encapsulation

Overestimating Service Demand

10.7 Case Study Example

Existing Implementation Autonomy of the GetItem Operation

New Operation-Level Architecture with Increased Autonomy

Effect on the Run Lab Project Composition

Chapter 11:Service Statelessness(State Management Deferral and Stateless Design)

11.1 State Management Explained

State Management in Abstract

Origins of State Management

Deferral vs.Delegation

11.2 Profiling this Principle

11.3 Types of State

Active and Passive

Stateless and Stateful

Session and Context Data

11.4 Measuring Service Statelessness

Non-Deferred State Management(low-to-no statelessness)

Partially Deferred Memory(reduced statefulness)

Partial Architectural State Management Deferral(moderate statelessness)

Full Architectural State Management Deferral(high statelessness)

Internally Deferred State Management(high statelessness)

11.5 Statelessness and Service Design

Messaging as a State Deferral Option

Service Statelessness and Service Instances

Service Statelessness and Granularity

Service Statelessness and Service Models

How Service Statelessness Affects Other Principles

11.6 Risks Associated with Service Statelessness

Dependency on the Architecture

Increased Runtime Performance Demands

Underestimating Delivery Effort

11.7 Case Study Example

Solution Architecture with State Management Deferral

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Step 7

Chapter 12:Service Discoverability(Interpretability and Communication)

12.1 Discoverability Explained

Discovery and Interpretation,Discoverability and Interpretability in Abstract

Origins of Discovery

12.2 Profiling this Principle

12.3 Types of Discovery and Discoverability Meta Information

Design-Time and Runtime Discovery

Discoverability Meta Information

Functional Meta Data

Quality of Service Meta Data

12.4 Measuring Service Discoverability

Fundamental Levels

Custom Rating System

12.5 Discoverability and Service Design

Service Discoverability and Service Modeling

Service Discoverability and Granularity

Service Discoverability and Policy Assertions

Service Discoverability and Service Models

How Service Discoverability Affects Other Principles

12.6 Risks Associated with Service Discoverability

Post-Implementation Application of Discoverability

Application of this Principle by Non-Communicative Resources

12.7 Case Study Example

Service Profiles(Functional Meta Information)

Related Quality of Service Meta Information

Chapter 13:Service Composability(Composition Member Design and Complex Compositions)

13.1 Composition Explained

Composition in Abstract

Origins of Composition

13.2 Profiling this Principle

13.3 Composition Concepts and Terminology

Compositions and Composition Instances

Composition Members and Controllers

Service Compositions and Web Services

Service Activities

Composition Initiators

Point-to-Point Data Exchanges and Compositions

Types of Compositions

13.4 The Complex Service Composition

Stages in the Evolution of a Service Inventory

Defining the Complex Service Composition

Preparing for the Complex Service Composition

13.5 Measuring Service Composability and Composition Effectiveness Potential

Evolutionary Cycle States of a Composition

Composition Design Assessment

Composition Runtime Assessment

Composition Governance Assessment

Measuring Composability

13.6 Composition and Service Design

Service Composability and Granularity

Service Composability and Service Models

Service Composability and Composition Autonomy

Service Composability and Orchestration

How Service Composability Affects Other Principles

13.7 Risks Associated with Service Composition

Composition Members as Single Points of Failure

Composition Members as Performance Bottlenecks

Governance Rigidity of""Over-Reuse""in Compositions

13.8 Case Study Example

PART III:SUPPLEMENTAL

Chapter 14:Service-Orientation and Object-Orientation:A Comparison of Principles and Concepts

14.1 A Tale of Two Design Paradigms

14.2 A Comparison of Goals

Increased Business Requirements Fulfillment

Increased Robustness

Increased Extensibility

Increased Flexibility

Increased Reusability and Productivity

14.3 A Comparison of Fundamental Concepts

Classes and Objects

Methods and Attributes

Messages

Interfaces

14.4 A Comparison of Design Principles

Encapsulation

Inheritance

Generalization and Specialization

Abstraction

Polymorphism

Open-Closed Principle(OCP)

Don恡 Repeat Yourself(DRY)

Single Responsibility Principle(SRP)

Delegation

Association

Composition

Aggregation

14.5 Guidelines for Designing Service-Oriented Classes

Implement Class Interfaces

Limit Class Access to Interfaces

Do Not Define Public Attributes in Interfaces

Use Inheritance with Care

Avoid Cross-Service""has-a""Relationships

Use Abstract Classes for Modeling,Not Design

Use Fa?ade Classes

Chapter 15:Supporting Practices

15.1 Service Profiles

Service-Level Profile Structure

Capability Profile Structure

Additional Considerations

15.2 Vocabularies

Service-Oriented Computing Terms

Service Classification Terms

Types and Associated Terms

Design Principle Application Levels

15.3 Organizational Roles

Service Analyst

Service Architect

Service Custodian

Schema Custodian

Policy Custodian

Service Registry Custodian

Technical Communications Specialist

Enterprise Architect

Enterprise Design Standards Custodian(and Auditor)

Chapter 16:Mapping Service-Orientation Principles to Strategic Goals

16.1 Principles that Increase Intrinsic Interoperability

16.2 Principles that Increase Federation

16.3 Principles that Increase Vendor Diversification Options

16.4 Principles that Increase Business and Technology Domain Alignment

16.5 Principles that Increase ROI

16.6 Principles that Increase Organizational Agility

16.7 Principles that Reduce the Overall Burden of IT

PART IV:APPENDICES

Appendix A:Case Study Conclusion

Appendix B:Process Descriptions

B.1 Delivery Processes

Bottom-Up vs. Top-Down

The Inventory Analysis Cycle

Inventory Analysis and Service-Oriented Design

Choosing a Delivery Strategy

B.2 Service-Oriented Analysis Process

Define Analysis Scope

Identify Affected Systems

Perform Service Modeling

B.3 Service Modeling Process

B.4 Service-Oriented Design Processes

Design Processes and Service Models

Service Design Processes and Service-Orientation

Appendix C:Principles and Patterns Cross-Reference

Additional Resources

About the Author

About the Photos

Index

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