Restful风格web服务架构
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This document provides an overview of REST (Representational State Transfer) and RESTful architectures. It begins with an introduction and agenda. It then defines REST and describes its key aspects like resources, representations, and the HTTP methods. It discusses the constraints and goals of REST, examples of RESTful systems, and why REST is advantageous for building distributed systems. Finally, it covers implementing RESTful services in Java using the JAX-RS API and frameworks like Jersey.
![Guiding principles of
the interface
• The uniform interface that any REST interface must provide is considered fundamental to the design of
any REST service.
• Identification of resources
• Individual resources are identified in requests, for example using URIs in web-based REST systems.
The resources themselves are conceptually separate from the representations that are returned
to the client. For example, the server does not send its database, but rather, perhaps, some HTML,
XML or JSON that represents some database records expressed, for instance, in Swahili and
encoded in UTF-8, depending on the details of the request and the server implementation.
• Manipulation of resources through these representations
• When a client holds a representation of a resource, including any metadata attached, it has enough
information to modify or delete the resource on the server, provided it has permission to do so.
• Self-descriptive messages
• Each message includes enough information to describe how to process the message. For example,
which parser to invoke may be specified by an Internet media type (previously known as a MIME
type). Responses also explicitly indicate their cacheability.[1]
• Hypermedia as the engine of application state (aka HATEOAS)
• Clients make state transitions only through actions that are dynamically identified within
hypermedia by the server (e.g., by hyperlinks within hypertext). Except for simple fixed entry
points to the application, a client does not assume that any particular action is available for any
particular resources beyond those described in representations previously received from the
server.
32](https://image.slidesharecdn.com/restfulweb-151123030133-lva1-app6891/85/Restful-web-32-320.jpg)
Restful风格web服务架构
- 2. about • Benjamin Tan • @tanbamboo • github.com/tanbamboo 2
- 3. agenda • Lesson 1 • what? • why? • Lesson 2 • how? • how? in Java(using JAX-RS) • Lesson 3 • good practice? bad practice? • more? 3
- 4. what? • what is REST? what is RESTful arch? 4
- 5. what? • Representational state transfer (REST) is a style of software architecture for distributed systems such as the World Wide Web. REST has emerged as a predominant web API design model. • Representational State Transfer REST Roy Fielding 2000 5
- 6. the Author of REST • Fielding HTTP 1.0 1.1 Apache Apache • • REST 6
- 7. REST Triangle • /nouns • /verbs • /content types 7
- 8. /Resources • REST " " " " " " Resources " " • " " • • URI URI • URI URI 8
- 9. • HTTP • GET • POST • PUT • DELETE • HEAD OPTIONS CONNECT TRACE 9
- 10. /Representation • " " • " " " / /Representation" • txt HTML XML JSON JPG PNG • URI 10
- 11. key goals • Scalability of component interactions • Generality of interfaces • Independent deployment of components • Intermediary components to reduce latency, enforce security and encapsulate legacy systems 11
- 12. Constraints • Client–server • Stateless • Cacheable • Layered system • Code on demand (optional) • Uniform interface 12
- 13. • REST REST HTTP URI XML HTML • URI • HTTP GET POST PUT DELETE • • XML HTML web web 13
- 15. HATEOAS • 15
- 16. REST Data Elements • Resource - the intended conceptual target of a hypertext reference • Resource identifier – URL, URN • Representation – HTML document, JPEG image • Representation metadata – media type, last- modified time • Resource metadata – source link, alternates, vary • Control data – if-modified-since, cache-control 16
- 17. REST Connectors • Client - libwww, libwww-perl • Server - libwww,Apache API, NSAPI • Cache - browser cache,Akamai cache network • Resolver - bind (DNS lookup library) • Tunnel - SOCKS, SSL after HTTP CONNECT 17
- 18. REST Components • User Agent – Netscape Navigator, Lynx, MOMspider • Origin Server – Apache httpd, Microsoft IIS • Gateway - Squid, CGI, Reverse Proxy • Proxy - CERN Proxy, Netscape Proxy, Gauntlet 18
- 19. why? 19
- 20. style design 20
- 21. REST • Cache • • • HTTP REST • • 21
- 22. network application style • / (MQ WebSocket) • (P2P ZooKeeper) • / 22
- 23. • • The PUT and DELETE methods are idempotent methods. • The GET method is a safe method (or nullipotent), meaning that calling it 23
- 24. Samples broken Idempotent • WebScan • Robot • http://stackoverflow.com/questions/ 10519064/why-is-using-a-http-get-to- update-state-on-the-server-in-a-restful- call-incorrec 24
- 25. RESTful & Cloud • • RESTful API • AWS API • Twitter API • http://www.infoq.com/news/2011/01/rest- cloud 25
- 26. RESTful & SOA 26
- 27. RESTful & RIA • • RIA+REST REST 27
- 29. Open Question? • RESTful WAF ? • RESTful LB ? • RESTful CDN ? 29
- 31. how? 31
- 32. Guiding principles of the interface • The uniform interface that any REST interface must provide is considered fundamental to the design of any REST service. • Identification of resources • Individual resources are identified in requests, for example using URIs in web-based REST systems. The resources themselves are conceptually separate from the representations that are returned to the client. For example, the server does not send its database, but rather, perhaps, some HTML, XML or JSON that represents some database records expressed, for instance, in Swahili and encoded in UTF-8, depending on the details of the request and the server implementation. • Manipulation of resources through these representations • When a client holds a representation of a resource, including any metadata attached, it has enough information to modify or delete the resource on the server, provided it has permission to do so. • Self-descriptive messages • Each message includes enough information to describe how to process the message. For example, which parser to invoke may be specified by an Internet media type (previously known as a MIME type). Responses also explicitly indicate their cacheability.[1] • Hypermedia as the engine of application state (aka HATEOAS) • Clients make state transitions only through actions that are dynamically identified within hypermedia by the server (e.g., by hyperlinks within hypertext). Except for simple fixed entry points to the application, a client does not assume that any particular action is available for any particular resources beyond those described in representations previously received from the server. 32
- 34. HTTP 34
- 35. 35
- 36. Cache • Proxy • Expires Cache-Control • Last-Modified ETag • 304 (Not Modified) 36
- 37. in one stentence • REST is everywhere. It is the part of the web that makes it work well. If you want to build distributed applications that can scale like the web, be resilient to change like the web and promote re-use as the web has done, then follow the same rules they did when building web browsers. • http://stackoverflow.com/questions/1368014/ why-do-we-need-restful-web-services 37
- 38. Good Practices • Map your API model to the way your data is consumed, not your data/object model. • Meaningful error messages help a lot. • Providing solid API documentation reduces need for external help. • Use an appropriate security APIs. 38
- 39. bad practices • Chatty APIs suck. • Returning HTML in response. • Failing to realize that a 4xx error means I messed up and a 5xx means you messed up • Side-effects to 500 errors are evil. • http://broadcast.oreilly.com/2011/06/the- 39
- 40. how? in Java (using JAX-RS) 40
- 41. JAX-RS • JSR 311: JAX-RS:The Java API for RESTful Web Services • Java EE 6 JSR-311 JSR-311 Java REST • JSR 339: JAX-RS 2.0 • Java EE 7 with JAX-RS 2.0 brings several useful features, which further simplify development and lead to the creation of even more-sophisticated, but lean, Java SE/EE RESTful applications. 41
- 43. JAX-RS • @POST @GET @PUT @DELETE 4 HTTP • @Path 43
- 44. JAX-RS • JAX-RS Resource @PathParam @MatrixParam @QueryParam @FormParam @HeaderParam @CookieParam @DefaultValue @Encoded • @PathParam @Path 44
- 45. JAX-RS • Web Content Negotiation • Resource @Produces MIME @Consumes • Accept Content- Type • JAX-RS MessageBodyReader MessageBodyWriter XML / Java JAXB • @Provider MessageBodyProvider 45
- 46. JAX-RS • Jersey • JBoos Resteasy • Apache Wink • Play! Framework 46
- 47. JAX-RS • Spring @MVC • Restlet 47
- 48. how? other languages • Rails(ruby) • Sinatra(ruby) • Tornado Web(python) • Django REST(python) • spray(scala) • More RESTful frameworks: • https://code.google.com/p/implementing-rest/ wiki/RESTFrameworks 48
- 49. more? 49
- 50. • HTTP WebSockets REST • REST • SSL/TLS REST WS-Sec* REST SSL REST REST • REST QoS “ ” 50
- 51. API versioning • API REST 51
- 52. POST • post • 52