1 面向服务与面向服务的体系架构概述 北京大学信息科学技术学院 2010年 2010 9 252 Outline SOA definition and its business and technology values Service orientation vs object orientation Service oriented architecture vs distributed object architecture 2 2010 9 253 What is SOA Just like object a generation ago services is now the killer buzzword However SOA is a often misunderstood topic in IT today My architect thinks it s service oriented my developers insist it s object oriented and my analysts wish it would be more business oriented All I can tell you is that it isn t what it was before we started building Web services 2010 9 254 What are Services Services may mean different things to different people Loosely coupled software components that interact with one another dynamically via standard Internet technologies Gartner 1996 A software application identified by a URI whose interfaces and binding are capable of being defined described and discovered by XML artifacts and supports direct interactions with other software applications using XML based messages via Internet based protocols W3C 3 2010 9 255 What are Services A piece of business logic accessible via the Internet using open standards Microsoft Encapsulated loosely coupled contracted software functions offered via standard protocols over the Web DestiCorp Services are self contained reusable software modules that are independent of applications and the computing platforms on which they run Services have with well defined interfaces and allow a 1 1 mapping between business tasks and the exact IT components needed to execute the task IBM 2010 9 256 What is SOA SOA definition is still evolving A set of components which can be invoked and whose interface description can be published and discovered W3C Service oriented architecture is a client server design approach in which an application consists of software services and software service consumers also known as clients or service requesters SOA differs from the more general client server model in its definitive emphasis on loose coupling between software components and in its use of separately standing interfaces Gartner 4 2010 9 257 What is SOA Service Oriented Architecture is a business driven IT architecture approach that supports integrating your business as linked repeatable business tasks or services SOA helps today s business innovate by ensuring that IT systems can adapt quickly easily and economically to support rapidly changing business needs SOA helps customers increase the flexibility of their business processes strengthen their underlying IT infrastructure and reuse their existing IT investments by creating connections among disparate applications and information sources IBM A New Way of Thinking 2010 9 258 A CD Player Example Take a CD for instance If you want to play it you put your CD into a CD player and the player plays it for you The CD player offers a CD playing service Which is nice because you can replace one CD player with another You can play the same CD on a portable player or on your expensive stereo They both offer the same CD playing service but the quality of service is different 5 2010 9 259 Service broker Registration Organization X Organization Z Organization Y Component Library Services FoundAuto searchable Application 1Application 2 Business Process The SOA Story RegistrationRegistration 2010 9 2510 Why Service Orientation M a r k et i n g Ma n uf a ct u ri ng A c c o un t i n g R e se ar c h D e ve l op m en t C u st o m e r S e r v i Sa le s Distributed Business Requires Distributed Computing Distributed Data Distributed Computation Distributed users Distributed Data Distributed Computation Distributed users M a r k eM a n u f a A c c o uR e s e a D e v e l o C u s t o m e r S a M a r k e M a n u f a A c c o u R e s e a D e v e l o C u s t o m e r S a Marketing Manufacturing Accounting Research Development Customer Service Sales 6 2010 9 2511 Why Service Orientation Interoperation issues Heterogeneous network protocols Heterogeneous hardware platforms Heterogeneous operating systems Heterogeneous application formats There must be consensus On Interoperability 2010 9 2512 Changing Market Dynamics Collaborative integrated value nets Dynamic adaptive learning Unpredictable fluctuations Shortening product lifecycle Proactive risk management Increased focus on privacy and security Fixed Costs Proprietary systems Labor intensive Users adapt to technology Variable costs Open integrated systems Self healing self managing systems Technology adapts to users BusinessTechnology Business process decision making Rigid organizational structure Slow and steady economic growth Long term product lifecycle Passive operational risk management StaticOn Demand Why Service Orientation 7 2010 9 2513 Why Service Orientation 2010 9 2514 Business Drivers New opportunities Innovative products and services from the key differentiator to gain competitive edge Ability to leverage technology to adopt newer business models thus en