Web API HTTP Pipeline

							Web API HTTP Pipeline




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Objectives
• Understand the client-side and server-side
  pipelines
• Send the best HTTP responses for Web API
  operations
• Use the HTTP pipeline objects to handle
  exceptions
• Write your own custom handlers for Web API
  requests

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Agenda
•   Pipeline Elements
•   Client-Side Pipeline
•   Server-Side Pipeline
•   Improving CRUD Responses
•   Exception Handling
•   Custom Handlers


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Pipeline Elements
•   Request/Response models have pipelines
•   Composed of sequential events that fire
•   Uses specific objects
•   Web API has client and server-side pipelines
•   Both share some common objects




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HttpRequestMessage
• Represents all the info about the HTTP request
  • URL
  • HTTP method
  • Headers




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HttpResponseMessage
• Represents all the info about the HTTP
  response
  • Status code
  • Success flag
  • Original HTTP request




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HttpMessageHandler
• Base class implemented by other objects
• Most custom processing code goes here
• Able to write custom handlers and put them in
  the pipeline




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Agenda
•   Pipeline Elements
•   Client-Side Pipeline
•   Server-Side Pipeline
•   Improving CRUD Responses
•   Exception Handling
•   Custom Handlers


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Client-Side Pipeline
 • HttpClient sends requests
 • Request is an HttpRequestMessage
 • Request is sent to HttpMessageHandler
 • HttpMessageHandler returns
   HttpResponseMessage
 • Default handler is HttpClientHandler



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Client-Side Pipeline




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Agenda
•   Pipeline Elements
•   Client-Side Pipeline
•   Server-Side Pipeline
•   Improving CRUD Responses
•   Exception Handling
•   Custom Handlers


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               Copyright © by Application Developers Training Company
Server-Side Pipeline
 • Web host gives the request to HttpServer
 • Request passed through series of
   HttpMessageHandlers
 • Ends with HttpControllerDispatcher
 • Dispatcher sends request to appropriate
   Controller which sends response



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Agenda
•   Pipeline Elements
•   Client-Side Pipeline
•   Server-Side Pipeline
•   Improving CRUD Responses
•   Exception Handling
•   Custom Handlers


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Improving CRUD Responses
• By default, Web API always sends same HTTP
  response code
• Can alter the response to include more
  accurate info




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Improving CRUD Responses
• Let’s improve a Web API service’s HTTP
  responses!




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              Copyright © by Application Developers Training Company
Agenda
•   Pipeline Elements
•   Client-Side Pipeline
•   Server-Side Pipeline
•   Improving CRUD Responses
•   Exception Handling
•   Custom Handlers


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               Copyright © by Application Developers Training Company
Exception Handling
• Exceptions tend to be vague on client
• HttpResponseException
• Can use filters to assign HTTP responses




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Exception Handling
• Let’s set up an automated way to send better
  error messages to the client




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              Copyright © by Application Developers Training Company
Agenda
•   Pipeline Elements
•   Client-Side Pipeline
•   Server-Side Pipeline
•   Improving CRUD Responses
•   Exception Handling
•   Custom Handlers


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               Copyright © by Application Developers Training Company
Custom Handlers
• Inherit DelegatingHandler
• Custom code to perform any kind of per
  request functionality
  • Logging
  • Security
  • Handling certain kinds of requests




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Custom Handlers
• We’ll add some security to a Web API service




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Learn More!
• This is an excerpt from a larger course. Visit
  www.learnnowonline.com for the full details!


• Learn more about Web API on SlideShare:
   Web API Basics




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