WEB SERVICES AN EVALUATION OF MODERN WEB SERVICE ARCHITECTURES Gordon Hew COMS E6125 Web Information Management Systems

Agenda  Introduction  Architectural Styles  Remote Procedure Call (RPC)  Serviced Oriented Architecture (SOA)  Representational State Transfer (REST)  Conclusion

Web Services & Architectural Styles  What are Web Services?  Why are they important?  What are some examples?  Why are Architectural Styles important?  What criteria will be using to evaluate these styles?

Remote Procedure Call (RPC)  RPC  Client invocation of a local representation of a remote method

Remote Procedure Call (RPC)  Example Technologies  XML-RPC  RPC Style SOAP  Advantages  Simple  Disadvantages  Tightly Coupled  Not Easily Scalable

Service Oriented Architecture (SOA)  SOA Principles  Separation of concerns  Service Orientation Loosely Coupled Formal Contracts Abstract Logic Composable Reusable Autonomous Stateless Discoverable

Service Oriented Architecture (SOA)  SOA Workflow

Service Oriented Architecture (SOA)  Primary Technologies  Document-centric SOAP  WSDL  UDDI  Advantages  Extensible  Scalable  Disadvantages  Excessive Configuration  Reliance on Tools

Representational State Transfer (REST)  REST Principles  Resource Oriented  Uniquely Addressable  Client-Server  Stateless  Cache  Uniform Interface  Layered System

Representational State Transfer (REST)  REST Workflow

Representational State Transfer (REST)  Example Framework  Restlet  Advantages  Extensible  Scalable  Content Types  Disadvantages  Data Size

Conclusion  REST is the best overall architecture style  Not too complex  Extensible  Interoperable  Scalable  Challenges to Adoption  Benefits are not immediately recognizable  Maturity  Investment in SOA

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