![11
HTTP PUT, HTTP POST
âą HTTP POST creates a resource
âą HTTP PUT updates a resource
âą POST http://localhost/books/
âą Content: {title, authors[], âŠ}
âą Creates a new book with given properties
âą PUT http://localhost/books/isbn-111
âą Content: {isbn, title, authors[], âŠ}
âą Updates book identified by isbn-111 with submitted properties](https://image.slidesharecdn.com/emilio-230206063430-a4f63203/85/emilio-ppt-11-320.jpg)
emilio.ppt
- 1. Representational State Transfer (REST): Representing Information in Web 2.0 Applications Emilio F Zegarra CS 2650
- 2. 2 Hypertext Transfer Protocol (HTTP) âą A communications protocol âą Allows retrieving inter-linked text documents (hypertext) âą World Wide Web. âą HTTP Verbs âą HEAD âą GET âą POST âą PUT âą DELETE âą TRACE âą OPTIONS âą CONNECT Browser Web Server GET /index.html HTTP/1.1 Host: www.pitt.edu HTTP/1.1 200 OK Content-Type: text/html <html><head>âŠ
- 3. 3 Representational State Transfer (REST) âą A style of software architecture for distributed hypermedia systems such as the World Wide Web. âą Introduced in the doctoral dissertation of Roy Fielding âą One of the principal authors of the HTTP specification. âą A collection of network architecture principles which outline how resources are defined and addressed
- 4. 4 REST and HTTP âą The motivation for REST was to capture the characteristics of the Web which made the Web successful. âą URI Addressable resources âą HTTP Protocol âą Make a Request â Receive Response â Display Response âą Exploits the use of the HTTP protocol beyond HTTP POST and HTTP GET âą HTTP PUT, HTTP DELETE
- 5. 5 REST - not a Standard âą REST is not a standard âą JSR 311: JAX-RS: The JavaTM API for RESTful Web Services âą But it uses several standards: âą HTTP âą URL âą XML/HTML/GIF/JPEG/etc (Resource Representations) âą text/xml, text/html, image/gif, image/jpeg, etc (Resource Types, MIME Types)
- 6. 6 Main Concepts Nouns (Resources) unconstrained i.e., http://example.com/employees/12345 Verbs constrained i.e., GET Representations constrained i.e., XML REST
- 7. 7 Resources âą The key abstraction of information in REST is a resource. âą A resource is a conceptual mapping to a set of entities âą Any information that can be named can be a resource: a document or image, a temporal service (e.g. "today's weather in Los Angeles"), a collection of other resources, a non-virtual object (e.g. a person), and so on âą Represented with a global identifier (URI in HTTP) âą http://www.boeing.com/aircraft/747
- 8. 8 Naming Resources âą REST uses URI to identify resources âą http://localhost/books/ âą http://localhost/books/ISBN-0011 âą http://localhost/books/ISBN-0011/authors âą http://localhost/classes âą http://localhost/classes/cs2650 âą http://localhost/classes/cs2650/students âą As you traverse the path from more generic to more specific, you are navigating the data
- 9. 9 Verbs âą Represent the actions to be performed on resources âą HTTP GET âą HTTP POST âą HTTP PUT âą HTTP DELETE
- 10. 10 HTTP GET âą How clients ask for the information they seek. âą Issuing a GET request transfers the data from the server to the client in some representation âą GET http://localhost/books âą Retrieve all books âą GET http://localhost/books/ISBN-0011021 âą Retrieve book identified with ISBN-0011021 âą GET http://localhost/books/ISBN-0011021/authors âą Retrieve authors for book identified with ISBN-0011021
- 11. 11 HTTP PUT, HTTP POST âą HTTP POST creates a resource âą HTTP PUT updates a resource âą POST http://localhost/books/ âą Content: {title, authors[], âŠ} âą Creates a new book with given properties âą PUT http://localhost/books/isbn-111 âą Content: {isbn, title, authors[], âŠ} âą Updates book identified by isbn-111 with submitted properties
- 12. 12 HTTP DELETE âą Removes the resource identified by the URI âą DELETE http://localhost/books/ISBN-0011 âą Delete book identified by ISBN-0011
- 13. 13 Representations âą How data is represented or returned to the client for presentation. âą Two main formats: âą JavaScript Object Notation (JSON) âą XML âą It is common to have multiple representations of the same data
- 14. 14 Representations âą XML âą <COURSE> âą <ID>CS2650</ID> âą <NAME>Distributed Multimedia Software</NAME> âą </COURSE> âą JSON âą {course âą {id: CS2650} âą {name: Distributed Multimedia Sofware} âą }
- 15. 15 Why is it called "Representational State Transfer"? Resource Client http://www.boeing.com/aircraft/747 Boeing747.html The Client references a Web resource using a URL. A representation of the resource is returned (in this case as an HTML document). The representation (e.g., Boeing747.html) places the client application in a state. The result of the client traversing a hyperlink in Boeing747.html is another resource accessed. The new representation places the client application into yet another state. Thus, the client application changes (transfers) state with each resource representation --> Representation State Transfer! Fuel requirements Maintenance schedule ...
- 16. 16 Request (XML doc) Response (XML doc) Web/Proxy Server HTTP GET URL 1 HTTP Response doGet() Request (XML doc) Response (JSON doc) HTTP POST URL 1 HTTP Response doPost(id) REST Engine (locate resource and generate response) PO (XML doc) HTTP DELETE URL 1 doDelete() Response (TEXT doc) HTTP Response Architecture Style
- 17. 17 Real Life Examples âą Google Maps âą Google AJAX Search API âą Yahoo Search API âą Amazon WebServices
- 18. 18 REST and the Web âą The Web is an example of a REST system! âą All of those Web services that you have been using all these many years - book ordering services, search services, online dictionary services, etc - are REST- based Web services. âą Alas, you have been using REST, building REST services and you didn't even know it.
- 19. 19 REST Implementations âą Restlet âą http://www.restlet.org/ âą Project Zero âą http://www.projectzero.org âą GlassFish Jersey âą https://jersey.dev.java.net/ âą JBoss RESTeasy âą http://www.jboss.org/resteasy/
- 20. 20 My Project - Web 2.0 IC Card âą Objective âą Transform the IC Card Application to support REST resources âą http://www.cs.pitt.edu/icms/iccards âą http://www.cs.pitt.edu/icms/iccards/001 âą http://www.cs.pitt.edu/icms/groups/1/users
- 21. 21 Invocation Model Client REST Service Database Channels http http SQL
- 22. 22 Tasks âą Design a REST resource model for the IC Card âą Review persistent model (MySql) âą Configure a REST engine (Project Zero) âą Create a new Rich User Interface (DOJO Toolkit)
- 23. 23 References âą Representational State Transfer http://en.wikipedia.org/wiki/Representational_State_Tr ansfer âą Roy Fieldings Thesis http://www.ics.uci.edu/~fielding/pubs/dissertation/top.h tm