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This document discusses the evolution of web APIs from SOAP to RESTful architectures. It covers the basics of REST including the Richardson maturity model, use of HTTP verbs and status codes, hypermedia, and content negotiation. Caching techniques are also discussed as a means of improving scalability. The overall summary is that HTTP provides a powerful application protocol for building web APIs and REST architectures allow these APIs to better leverage the inherent scaling capabilities of the web.
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- 1. REST Assured Yaniv Rodenski Senior Consultant,Sela Group http://blogs.microsoft.co.il/blogs/roadan Twitter: @YRodenski
- 2. A brief historyof The Web API March 2012 ASP.NET is Open Source 6 Preview Versions Fab 2012 ASP.NET Web API (Beta) October 2010 WCF Web API on Code Plex
- 4. State of theweb • Today the web faces new challenges: – Internet scale applications – Cloud operating systems
- 5. State of theweb • Today the web faces new challenges: – Even more complex integrations
- 6. State of theweb • Today the web faces new challenges: – Broader reach of clients
- 7. Agenda • Basic terminology •REST via the ASP.NET Web API – Richardson maturity model – Hypermedia Patterns – Media types • Caching
- 8. SOAP • Promise toadd “object access”-like semantics to the web – Operation centric – Uses a large message format • Extensible – Over the years a large amount of extending standards were created (AKA WS-*) – By extension, adds stateful semantics over the web • Promotes the use of the proxy pattern • Not web natural • Supported by major development environments
- 9. SOAP Service calls •Request • Response
- 10. HTTP • Promise totransfer hypertext • The primal and most native protocol of the web • Stateless • Supported by almost any device on the face of the earth
- 11. HTTP Service calls •Request • Response
- 12. SOA • SOA isan architectural approach for distributed systems • SOA defines four tenets focusing on service autonomy and boundaries • SOA is a fully mature architecture with well- known patterns and solutions for complex communication and integration scenarios
- 13. REST • The termRepresentational State Transfer (REST) was coined by Roy Fielding in his Ph.D. thesis in 2000 • An architectural style that embraces HTTP and the World Wide Web • Web friendly
- 14. Richardson maturity model •Leonard Richardson’s maturity model describes four levels of service maturity Hypermedia Http Resources
- 15. RMM – Levelzero services • Level zero services do not use HTTP as an application protocol. • Use HTTP as a transport for other remote interaction mechanism Hypermedia Http Resources
- 16. RMM – Levelone services • Level one services acknowledge resources • Resources are accessed via a unique address (formatted as a Universal Resource Identifier) • When accessed, a resource returns a representation http://myfooty.com/players/henrique http://myfooty.com/players/neymar Hypermedia Http Resources
- 17.
- 18. Web neutrality • Inhis famous 2001 bath-tub talk Don Box drew the line between web pages and web services by defining their consuming life forms: Carbon based Silicon based Web Pages Web Services
- 19. RMM – Leveltwo services • Level two services use HTTP mechanisms properly: – Verbs – Status codes – Headers Hypermedia Http Resources
- 20. HTTP verbs • HTTPdefines different methods (sometimes called verbs) to indicate a desired action to be performed on a resource • These verbs define a common terminology that is accepted by users, developers and the infrastructure of the World Wide Web
- 21. Using HTTP verbsfor CRUD
- 22. HTTP status codes •In addition to a response message, HTTP uses status codes to communicate to the clients the resultant status of the operation • The first digit of the status code specifies one of five classes of response: – 1xx Informational – 2xx Success – 3xx Redirection – 4xx Client Error – 5xx Server Error
- 23. HTTP headers • HTTPuses headers to transfer metadata regarding the message’s content and transport • HTTP headers are one of HTTP’s main extensibility points
- 24.
- 25. RMM – Levelthree services • Level one and two services deal with resources which represent entities • Level three services introduce flow management via hypermedia controls (For example: links) Hypermedia Http Resources
- 26. RMM – Levelthree services • Hypermedia is used as a logical extension of the term hypertext in which graphics, audio, video, plain text and hyperlinks intertwine to create a generally non-linear medium of information. http://en.wikipedia.org/wiki/Hypermedia Hypermedia Http Resources
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- 28. Hypermedia Patterns • Hypermediacan be used to express different behaviors in an application: – Control flow management (State machine) – Discoverability and versioning – Properties management – Aspect management – Paging
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- 30. Media types (MIME) •HTTP media types are used to describe the format of the message body • In REST media types are used describe representations, hypermedia controls, and processing rules • By creating a media type we can define the application’s domain
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- 32. Cache the REST •HTTP caches can store copies of the responses along the request response path to reduce network traffic • HTTP caches reduces call latency • Caches are a main factor for scalability on the web
- 33. Types of Cache •Browser Cache Stores representations locally on the computer’s hard drive • Proxy Cache Corporates and ISPs provide shared proxies providing shared cache on their network • Gateway (Reverse Proxy) Cache Stores representations on behalf of the server. Content Delivery Networks (CDNs) use gateway cache distributed around the web
- 34. Controlling Cache • HTTPheaders can be used to control cache behaviors • HTTP provides method the avoid staleness of cached data – Expiration – Validation
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- 36. Summary • HTTP isa powerful application level protocol • Built to serve the worlds largest information system • REST provides an architecture that enables better use of the inherent scaling capabilities of the web • Hypermedia enables us to scale and grow our application
- 38. My Blog ASP.NET Web APIs http://bit.ly/roadan http://www.asp.net/web-api/ (best viewed from multiple ip addresses) Architectural Styles and the Design of HTTP/1.1 Specifications http://www.w3.org/Protocols/ Network-based Software Architectures Roy Fielding http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm REST in practice (Book) http://restinpractice.com/default.aspx Debugging the web with Fiddler Ido Flatow http://scc.sela.co.il/SCC/Pages/ShowLecture/ShowLecture.aspx?lectureId=642
Editor's Notes
- #11 Focuses on improving web communication by using mechanizes like caching, ETags, the TRACE verb etc.
- #14 Focuses on improving web communication by using mechanizes like caching, ETags, the TRACE verb etc.
- #17 This model allows a resource to manage its own state while the client manages the application stateRepresentations can also be cached
- #19 The “web” uses resources and their representations for caching and scalability.Resources prevent the need to dibranchiate web pages and services
- #26 This model allows a resource to manage its own state while the client manages the application state
- #27 This model allows a resource to manage its own state while the client manages the application state