The ASP.NET Web API for Beginners
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This document provides an overview and examples for building web APIs with ASP.NET Web API. It discusses Richardson maturity levels, the HTTP request/response processing pipeline, attribute routing, and implementing handlers. It also demonstrates testing Web API controllers with the WebApiTestClient without requiring a running host. Key topics include building controllers, adding OData query support, creating an authorization handler, and following the Arrange, Act, Assert pattern for tests.
The ASP.NET Web API for Beginners
- 1. The ASP.NET Web API for Beginners W. Kevin Hazzard
- 3. The Web API Experience • Solid resource-orientation • HTTP method support • Content negotiation • Open-ended formatting • Model-binding • Minimal platform dependencies • Test friendly Level 3 Level 2 Level 1 Level 0
- 4. H A T E O A S Hypermedia As The Engine Of Application State H A T E O A S
- 6. Web API Processing Architecture HttpRequestMessage HttpResponseMessag e
- 7. HTTP Request GET /index.html HTTP/1.1 Accept: text/html Accept-Encoding: gzip, deflate Accept-Language: en-US User-Agent: Mozilla/5.0 Connection: Keep-Alive
- 8. HttpRequestMessage • In System.Net.Http namespace • Properties: o Content – HttpContent o Headers – HttpRequestHeaders o Method – HttpMethod o Properties – IDictionary<string, object> o RequestUri – Uri
- 9. Request Extensions • CreateErrorResponse – many overloads • CreateResponse – many overloads • GetClientCertificate • GetProperty<T> • GetQueryNameValuePairs • GetUrlHelper These are in System.Net.Http.dll.
- 10. HTTP Response HTTP/1.1 200 OK Cache-Control: private, max-age=0 Content-Type: text/html; charset=utf-8 Vary: Accept-Encoding Date: Thu, 31 Dec 2015 23:59:59 GMT Content-Length: 41309 Connection: keep-alive Set-Cookie: XYZ=123; domain=.me.com; path=/ ...
- 11. HttpResponseMessage • In System.Net.Http namespace • Properties: o Content – HttpContent o Headers – HttpResponseHeaders o IsSuccessStatusCode – bool o ReasonString – string o RequestMessage – HttpRequestMessage o StatusCode – HttpStatusCode
- 12. Key Attributes o HttpGet o HttpPost o HttpPut o HttpPatch o HttpDelete o HttpHead o HttpOptions o AcceptVerbs o Authorize o AllowAnonymous o NonAction o FromBody o FromUri o Queryable
- 13. Example One Create a Simple Controller to Fetch Person Entities Add OData Query Syntax Support
- 14. Example One Summary • Implement a basic controller with a actions • Demonstrate controller selection by convention • Discuss controller selection by attribution • Implement OData query parameters and demonstrate
- 15. Example Two Add WebApiTestClient to the Project and Configure Turn Documentation Comments on and Configure
- 16. Cross-Cutting Concerns HttpMessageHandler class: protected abstract Task<HttpResponseMessage> SendAsync( HttpRequestMessage request, CancellationToken token);
- 17. DelegatingHandler Derives from HttpMessageHandler Chains handlers together in the order you add them
- 18. Chained Handlers Server SendAsync SendAsync SendAsync
- 19. Example Three Implement an Authorization Key Handler
- 20. Example Three Summary • Implement an application key handler • Discuss the invocation of the InnerHandler • Demonstrate the creation and return of an error response • Discuss why throwing exceptions will always return an HTTP 500 (Internal Server Error) result • Demonstrate using the request object to create the error response instead • Attach the handler to the pipeline • Debug with Help & Test
- 21. Possible Uses • Implementing a cache manager • Implementing an AAA scheme • Capturing pay-per-call data • Recording statistics • Logging and tracing • Inserting custom request and response headers • Performing message compression or encryption • Transforming messages
- 22. Testing Web API • Faking context with ASMX and WCF is difficult • Too many platform dependencies o ASP.NET produces an HttpContext o WFC produces an OperationContext • Typically requires a running host
- 24. Example Four Summary • Add test fixtures • Demonstrate Arrange, Act, Assert pattern • Call controller action without HttpRequestMethod • Call controller action with HttpRequestMethod
Editor's Notes
- #6: Values idealism over pragmatism and app longevity over short-term efficiencyResult: nobody does it correctly