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Doing REST with new WCF Web API

Himanshu DesaiSenior Consultant - Readify

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Agenda

• Web as Resource Oriented Architecture• Current Industry Trends• Overview of REST–What is REST? – REST Constraints– REST Benefits

• REST using WCF– REST Support in WCF–WCF Web API

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Resource Oriented Architecture

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Current Industry Trends

• A Move to cloud-based computing• A Migration away from SOAP• More browser based Apps• Adoption of REST• Other standards like OAuth,

WebSockets

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What is REST?

• Representational State Transfer• Idea floated by Roy Fielding• Architecture Style (not a protocol or

spec and it is not restricted to HTTP)

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REST Constraints

• Client - server• Stateless• Cacheable• Layered• Uniform interface

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REST Constraints

• Uniform interface• Client - server• Stateless• Cacheable• Layered

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REST Benefits

• Scalability of component interactions• Evolvability• Reach• Intermediary components to reduce

latency, enforce security and encapsulate legacy systems

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RESTful Services-1

• A Traditional RPC based Service

• Moving from Verb to Noun– Users– Bookmarks

Operation Description createUserAccount Creates a new user accountgetUserProfile Retrieves a specific user’s

public profile informationcreateBookmark Creates a new bookmark for

the authenticated user

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RESTful Services-2

• Designing the Uri Template– An invidual user account– An individual bookmark– A user’s collection of private/public

bookmark– Collection of all public bookmarks

• Applying the Uniform HTTP Interface

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RESTful Services-2

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RESTful Services-3

• Designing Resource RepresentationMethod URI Template Equivalent RPC

Operation PUT users/{username} createUserAccountGET users/{username} getUserAccountPUT users/{username} updateUserAccountDELETE users/{username}/

bookmarks/{id}deleteBookmark

GET users/{username}/bookmarks/{id}

getBookmark

GET users/{username}/bookmarks?tag={tag}

getUserBookmarks

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RESTful Services-4

• Designing Resource Representation<User>

< Email>aaron@pluralsight.com</Email><Name>Aaron Skonnard</Name>

</User>

• Supporting Alternate Representation?tag={tag}&format=json{username}?tag={tag}&format=jsonusers/{username}?format=jsonusers/{username}/profile?format=json

• Security Consideration• Providing Resource Metadata• Avoiding RPC Tendencies

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REQUEST

GET /index.html

Host: www.example.comRESPONSEHTTP/1.1 200 OK

Etag: „3f80f-1b6-3e1cb03b”

Content-Type: text/html;

charset=UTF-8l

GET Example

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POST /order HTTP/1.1Host: amazon.netContent-Type: application/xmlContent-Length: 216<order xmlns="http://schemas.amazon.net/order"><drink>latte</drink></order>

201 CreatedLocation: http://amazon.net/order/1234ContentType: application/xml<order xmlns="http://schemas.amazon.net/order">...

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POST Example

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PUT /payment/1234 HTTP/1.1Host: amazon.netContent-Type: application/xmlContent-Length: 216<payment xmlns="http://schemas.amazon.net/order"><cardNumber>...</cardNumber></order>

200 OKContentType: application/vnd.amazon+xml xmlns="http://schemas.amazon.net/order"><drink>Latte</drink><link href=„payment/1234” rel=„http://relations.amazon.net/payment”/></order>

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PUT Example

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REST Using WCF

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Rest Support Comparison

.NET 3.0 & 4.0 Web API

WebGet/WebInvoke Support Available

Partial Support for Content Negotiation

Full Support

Partial HTTP Support Full Power of HTTP

Limited Reach Maximise Reach

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Message Handler 1

Transport+Encoder

Op Handler2

Resource

Response

Architecture

Dispatcher

Message Handler 2

GetById?

Op Handler 4

Op Handler 3

Requ

est

Op Handler 1

GetById?

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Components

Content Negotiation

Central Configuration (Fluent API)

Http Classes

Operation Handler Factory Error Handler

Message Handler Factory(Channel

Level)

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Classes for Request & Response

• HttpRequestMessage• HttpResponseMessage• HttpContent• HttpClient

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Content Negotiation

• Support for Multiple Formats including an add-in model– if you want xml ,it gives xml and if you

want Json, it gives Json

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Demo

• Content Negotiation

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Operation Handler Factory

• Responsible for creating new instances of Media Type Formatters and Operation Handlers.

• Media Type Formatter • Operation Handler - an abstract base

class used to create transfer a set of input into a set of output

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Operation Handler Factory

Request Pipeline Response Pipeline

Operation Handler

Operation Handler

Operation Handler

Operation Handler

Operation Handler

Operation Handler

Dispatch

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Message Handler Factory

Ope

ratio

nMessage Handler 1

Message Handler2

Message Handler3

Message Handler4

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Query Composition

• Support for OData like query support–http://localhost/AlbumService/

albums?$Top=5–http://localhost/AlbumService/

albums?$Top=5&$OrderBy=Title

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Consuming RESTful Services

• Consuming with Javascript• Consuming with WCF

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Consuming Web API with Javascript

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HttpClient

• Helps you access web resources using Linqvar client = new HttpClient(address);

var personQuery = client.CreateQuery<Person>(); var results = personQuery.ExecuteAsync().ContinueWith(p =>

{//Dosomething here

});

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Demo

• Query Composition & HttpClient

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Questions?