1. REST and the WCF Web API Getting started with REST services and the WCF Web API Maurice de Beijer

2. Objectives What are REST services Why REST instead of SOAP The WCF Web API framework The next webinar on the 25th of October is about creating HTML5/JavaScript clients for REST services

3. What are REST services Representational State Transfer A way of creating web services Not using the WS-* SOAP specifications All about resources Not about calling functions, RPC Embraces HTTP Not just a way of getting data across the wire Leverages the structure of the Internet URLS MIME Media Types HTTP Methods Caching Security

4. The origin of REST Architectural Styles and the Design of Network-based Software Architectures By Roy Thomas Fielding Chapter 5 One of the authors of the HTTP specification

5. Why are REST services popular Almost every platform supports consuming them All you need is an HTTP client stack Many services are build around resources CRUD style Enables very scalable services Build around the technology that powers the Internet

6. The WCF Web API framework On CodePlex http://wcf.codeplex.com/wikipage?title=WCF%20HTTP Use NuGet from within Visual Studio 2010 http://nuget.org/ Current version 0.5 Much better than the original WCF support for REST But doesn’t replace it

7. The resource URL The URL is the key to a resource http://bookshop.com/books (The collection of books) http://bookshop.com/books/12345(An individual book) A given URL always returns the same resource Deleting one resource doesn’t change the URL of another resource But a resource can have multiple URL’s http://bookshop.com/orders/12345 http://bookshop.com/customers/12345/orders/12345

8. Different request/response formats Uses standard HTTP MIME Media Types http://www.iana.org/assignments/media-types/index.html Content Negotiation The client specifies a list of acceptable media types The server chooses the best supported media type to return XML Good general purpose data format JSON Optimised for usage with JavaScript clients Custom formats Use one of the many IANA types Define your own Normally prefixed with vnd. Example: application/vnd.wordperfect

9. HTTP Status codes Tell the client application what happened Successful 2xx 200 OK 201 Resource created Redirection 3xx 301 Moved Permanently Client Error 4xx 400 Bad request 404 Not found Server Error 5xx 500 Internal Server Error 503 Service Unavailable

10. HTTP GET Method No side effects Can retrieve it as often as you like Allows for caching Request may never get to the server Makes the web as scalable as it is Use Accept header to specify the acceptable media type Multiple types are supported Examples: Accept: application/xml Accept: application/json Accept: image/jpeg, image/*; q=0.5

11. Other HTTP Methods POST Creates new resource Returns the URL to the created resource PUT or PATCH Replaces/updates resource Idempotent PATCH only replaces a part of the resource DELETE Removes resource Idempotent

12. Microformats Enable a much smarter client application Embed allowed actions with a resource Client can update the UI based on the resource OData is a good example Based on AtomPub http://www.odata.org Roll your own Or reuse an existing one from IANA Set the content-type Use your own application/vnd.xxx

13. Rest is not perfect No metadata Little tooling in Visual Studio 2010 It’s harder than it seems There is no official REST standard There are many strong opinions about what is REST and what is not

14. Usefull resources Essential Windows Communication Foundation 4 Training http://www.develop.com/training-course/windows-communication-foundation-wcf Hypertext Transfer Protocol -- HTTP/1.1 http://tools.ietf.org/html/rfc2616 The Atom Syndication Format http://tools.ietf.org/html/rfc4287 The Atom Publishing Protocol http://tools.ietf.org/html/rfc5023 Open Data Protocol (OData) http://www.odata.org WCF Web API Contrib http://webapicontrib.codeplex.com Fiddler http://www.fiddler2.com

15. Summary REST is all about resources CRUD actions REST embraces HTTP and the web HTTP isn’t just a means of moving bits REST services are a good way to build scalable services Build on the infrastructure of the web REST allows for very flexible services You control every part of the message