![JSON
Javascript Object Notation
• Lightweight Data Interchange Format – No tags
• Easy to parse and create
• Supports objects and Arrays
• We use Jackson Framework for JSON conversions
JSON Example:
{
“servers": [
{ “name":“server1" , “category":“Blade" },
A
Array A { “name":“Server2" , “category":“DL360" },
{ “name":“Server3" , “category":“DL480" }
]
} Object](https://image.slidesharecdn.com/rest-presentation-121213012311-phpapp02/85/Rest-presentation-18-320.jpg)
Rest presentation
- 1. REST - Basics Srividhya Umashanker
- 2. We are talking about …… 1. Introduction • Webservices, SOAP,vs REST 2. Spring – Rest, JSON • REST using Spring • Annotations • REST example with Spring
- 3. Introduction 1. Webservices 2. SOAP 3. What is REST? 4. SOAP vs REST 5. REST in Detail • Frameworks, • HTTP Methods, • HTTP Headers • Status Code
- 4. Web Services!! • Exposing existing software over the web (HTTP) • Deployed independent of the OS and Programming Languages • Standardized Protocol • Easily connecting Different Applications i.e., Interoperability • Low Cost of communication Service request validateCreditCard Number-1828282828282828 Server ICICI Bank ebay.com Credit Card Web Service Service Response “Name does not match”
- 5. SOAP? Simple Object Access Protocol • A simple XML-based protocol to let applications exchange information over HTTP. • WSDL defines endpoint, i/o format, security etc • Example : getUser(userName);
- 6. What is REST? - Rest Triangle • REST is a new and improved form of web Nouns : services. http://localhost/rest/user/123 • Introduced as SOAP is complex 4 • There isn’t a standard for REST architectures • Expose directory structure-like URIs • Used to expose a public API over the internet to handle CRUD operations on data. • Works on Nouns, Verbs, Content Types Content Types Verbs JSON, XML, HTML…. GET, POST …. GET /server/1234 POST /server?name=SERVER-1&id=1234
- 7. SOA vs REST – The right webservice GET /user/Robert GET /adduser?name=Robert getUser(userName);
- 8. Rest Frameworks – List Apache CXF Jersey Rest Easy Restlet Spring MVC
- 9. HTTP METHODS – CRUD in REST Methods CRUD Example Fetch all or any GET /user/ - Fetch all GET resource GET /user/1 – Fetch User 1 POST Create a Resource POST /user?name=user1&age=20 PUT /user/1? name=changed- PUT Update a Resource user1&age=22 DELETE Delete a Resource DELETE /user/1 Fetch Metainfo as HEAD HEAD /user header Fetch all VERBS OPTIONS OPTIONS /user allowed
- 10. HTTP Headers - To remember Headers Example Auth:<session-token> Auth:1ajkdsdajsd922j-w8eis0-jssjss Session token by logging in to Atlas Accept:<media Type> accept: application/json – Default Content-Type content-type:application/json Allow: Which method requests are allowed by the server
- 11. HTTP Status Codes To Remember - Status Codes 200 – OK Successful Return for sync call 307 – Temporarily Moved Redirection 400 – Bad Request Invalid URI, header, request param 401 – Un authorized User not authorized for operation 403 – Forbidden User not allowed to update 404 – Not Found URI Path not available 405 – Method not Method not valid for the path allowed 500 – Internal Server Server Errors Error 503 – Service Server not accessible unavailable
- 12. Spring 3 - REST • Spring Framework - Introduction • Dispatcher Servlet • Flow - Rest calls in Spring • Annotations for REST • REST Example with Spring
- 13. Spring Framework • The Spring Framework is an opensource, lightweight, Aspect based Inversion of Control container for the Java platform • helps "wire" different components together. • Spring's REST support is based upon Spring's annotation-based MVC framework • configure your servlet container as you would for a Spring MVC application using Spring's DispatcherServlet. http://static.springsource.org/spring/docs/3.0.0.M3/reference/html/ch18.html
- 14. Dispatcher Servlet <web-app> <servlet> <servlet-name>rest</servlet-name> <servlet-class> org.springframework.web.servlet.DispatcherServlet </servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>rest</servlet-name> <url-pattern>/rest/*</url-pattern> </servlet-mapping> </web-app>
- 15. Flow – REST calls in Spring HTTP Request Rest Template Dispatcher Servlet @ResponseBody Client Calls HTTP Response Jackson Converter @Controller @Service DB
- 16. Rest Template Spring Framework’s RestTemplate provides simple ways to make requests to RESTful services. Allows all REST METHODS – GET, POST, DELETE, PUT, HEAD, OPTIONS
- 17. Spring Annotations for REST Annotations Usage Example showing Annotations mark the class as a MVC @Controller @Controller controller @RequestMapping(value = “/ilo”) @RequestMappi Maps the request with path public class iLOController ng { @RequestMapping(value = “/server/{id}”, method = RequestMethod.GET) @PathVariable Map variable from the path public @ResponseBody Book getServer(@PathVariable String id) { System.out.println(“------Gettting Server ------”+id); unmarshalls the HTTP response body into a Java } @RequestBody object injected in the …… method. …….. } marshalls return value as @ResponseBody HTTP Response @Configuration Spring Config as a class
- 18. JSON Javascript Object Notation • Lightweight Data Interchange Format – No tags • Easy to parse and create • Supports objects and Arrays • We use Jackson Framework for JSON conversions JSON Example: { “servers": [ { “name":“server1" , “category":“Blade" }, A Array A { “name":“Server2" , “category":“DL360" }, { “name":“Server3" , “category":“DL480" } ] } Object
- 19. We are Done!
Editor's Notes
- #5: Webservices running on Linux and jbosscan be consumed from Windows .NET based applicationWebervices makes it easy to talk to each other
- #9: Jersey is the JAX-RS Implementation
- #10: A HEAD request is just like a GET request, except it asks the server to return the response headers only, The response to a HEAD request must never contain a message body, just the status line and headers.
- #14: "Dependency injection is where you design your classes so that they expect an outside actor to directly give them the sub-tools they need to do their jobs before anybody starts asking them to do something.“Annotations – adding metadata to the java elements like class, interfaces, methodsSpring uses annotations as an alternative to XML for declarative configuration
- #15: The DispatcherServlet consults the HandleMapping component to dispatch a request to a Controller.The BeanFactory interface provides an advanced configuration mechanism capable of managing objects of any nature. The ApplicationContext interface builds on top of theBeanFactory (it is a sub-interface) and adds other functionality such as easier integration with Spring's AOP features, message resource handling (for use in internationalization), event propagation, and application-layer specific contexts such as the WebApplicationContext for use in web applications.
- #16: What is Jackson,
- #18: TODO - What are annotations?