REST vs SOAP for Web Services

1. REST vs SOAP for Web Services Applications and Services in Internet Benjamin Hilaire – 81747L benjamin.hilaire@gmail.com

2. Summary 1- Introduction 2- Differents approachs 3- Simple Object Access Protocol (SOAP) 4- Represational State Transfer (REST) 5- Web Services in practice 6- Conclusion

3. Introduction • Computer changes • Hardware • was central mainframe • is many specialized server • Software • was specific • is re-usable • Network • was local (LAN) • is global (Internet) • New principles • Modularity • Interoperability • Normalized protocols

4. What is a Web Service ? • ”A web service is a network accessible interface to application functuonnality, built using standard Internet technologies” (Programming Web Services with SOAP, James Snell, O’Reilly, 2001) • Internet-oriented services • Most famous : Google Search • REST : http://www.google.com/search?q=web+services • SOAP • More complex : Google Documents • Online office service using only the browser • Non Internet-oriented service • Replace Electronic Data Interfaces (EDI) • New remote interface • Light client (ie Website) • Heavy client (ie Software) POST search/beta2 HTTP/1.1 Host: api.google.com Content-Type: application/soap+xml SOAPAction: urn:GoogleSearchAction <?xml version="1.0" encoding="UTF-8"?> <soap:Envelopexmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Body> <gs:doGoogleSearchxmlns:gs="urn:GoogleSearch"> <q>web+services</q> ... </gs:doGoogleSearch> </soap:Body> </soap:Envelope>

5. Why 2 standards ? • 2 standards from 2 fields • Software • Need for distributed system • Remote Call Procedure (1988) • XML+RPC -> XML-RPC (1998) • SOAP (2000) • SOAP standard W3C (2003) • Network • Building the World Wide Web • HTTP (1996) • XML (1998) • REST as the Web architecture (2000) • Rest for Web Services (>2002)

6. SOAP – Principles (1/2) • SOAP • Use of object remotely by message sending • Proposed by Microsoft and IBM • Supported by the Web Services Interoperability Organization (WS-I) • Standard packaging protocol for Web Services • XML enveloppe • Header • How process the message • Body • XML message • Calling methods from to a distant object • Embedded in transports messages

7. SOAP – Principles (2/2) • Web Services Technology Stack (WS-*) • UDDI : Universal Description Discovery Integration • WSDL : Web Service Description Language • SOAP : Simple Object Access Protocol

8. SOAP - Properties • Well know architecture • Remote object call (ie like Java Message Service) • Standard object programmation • WSDL  interfaces • Network used can be transparent • Statefull • Transaction-state persistent • All objects can be considered as locals • Message rejection • Detect network error (don’t trust the WWW) • Security • OASIS (company consortium) built standards protocols • All kind of web cryptography protocols (Key exchange, signature, certifications, secure transport,...)

9. REST - Principles • Origin • Architecture descripted by Roy Thomas Fielding in 2000 • Same architecture as the WWW • REST rest on the WWW • HTTP • TCP/IP • No upper layer • URI • Universal Ressource Identifier  URL for web pages • HTTP Methods as interface • GET (get a ressource) • PUT (set a ressource) • POST (modify a ressource) • DELETE (delete a ressource)

10. REST - Properties • Main objectives • Simplicity • Scaleability • Stateless • Server don’t keep track on previous request • Cache • Possibility to cache the response to earn time • Uniform Interface • 4 known-methods per ressource • Security • Secure transport method (SSL/HTTPS) • Main issue

11. Web Services in practice (1/3) • 2 philosophies • SOAP • RESTfull (all properties respected) • Not RESTfull • Hybrid • New architecture – new protocols • SOAP close to usual programming style • RPC via internet • Created/supported by company • REST close to Internet concepts • Simple - Efficient • Open-source community • New frameworks (exemples) • Microsoft .NET • Ruby On Rails

12. Web Services in practice (2/3) • Main visibles differences • Messages sizes • REST use HTTP only • SOAP use HTTP+XML enveloppe • Number of methods (4 vs N) • Stateless or statefull • Storing transaction improve performance and easiest architecture • Stateless mean complex architecture and redondant information sent but performance • Transparency – Intuitivness • REST is user-friendly : can be used without noticing • SOAP needs WSDL and UDDI to be used • Security • SOAP is well-known since 8 years : knows how use it in secure way • REST is brand-new and mostly use transport security

13. Web Services in practice (3/3) • What approach for what application • Technical choice • Internet-oriented or not • User-oriented or machine-oriented • Quality’s needed • Practical choice • Developping team knowledge’s • Server/Languages used • ”Marketing” choice • REST is new, fresh, fashion, nice • SOAP is old, reliable, secure, serious • Hybrid method • Read-only Approach (ROA) • REST for GET • SOAP for other methods

14. Conclusion • REST vs SOAP for Web Services • 2 different approachs, phylosophies • Choice according different criteria • Hybridation possible • Future of Web Service • More and more Web Services everywhere • On Internet • Remember the milk • iGoogle • On Computer • Gadget/Widgets layers • On ”big” systems • New interfaces • Google Gears • Cloud computing

15. Thanks ! Questions ?