ASP.NET Web API

ASP.NET Web-API is a powerful service framework sitting over Asp.Net MVC and lets the developer enforce a RESTful architectural style. After a brief discussion on how the request and response flow in the WebApi pipeline, we will dig into the main extensibility points and see how flexible is the infrastructure. In particular, we will see scenarios like content negotiation, validation, versioning, hosting outside IIS and few others.

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4. Browser Request Index.html MVC4 Traditional Request / Response for ALL rendered content and assets
5. Initial Request Application.htm MVC4 RequireJS Loader Page1 Partial.htm IndexViewModel.js Application.js (bootstrap) ViewModel (#index) ViewModel (#login) Model (LoginModel) JSON Requests HTML5 localstorage Handling disconnection
6. Source: www.programmableweb.com – current APIs: 4,535
10. POST SimpleService.asmx/EchoString HTTP/1.1 Host: localhost:1489 User-Agent: Mozilla/5.0 Accept: text/html Content-Type: application/json; Content-Length: 27 ... XML, JSON, SOAP, AtomPub ... Headers Data Verb URL
11. POST SimpleService.asmx/EchoString HTTP/1.1 Host: localhost:1489 User-Agent: Mozilla/5.0 Accept: text/html,application/xhtml+xml Content-Type: application/json; Content-Length: 27 ... { "Age":37, "FirstName":"Eyal", "ID":"123", "LastName":"Vardi“ } Headers Data Verb URL <Envelope> <Header> <!–- Headers --> <!-- Protocol's & Polices --> </Header> <Body> <!– XML Data --> </Body> </Envelope>
12. SOAP REST OData JSON POX ??
13. SOAP REST OData JSON POX ??
14. Dependency Injection Filters Content Negotiation Testing
15. Embrace HTTP
19. “An architectural style for building distributed hypermedia systems.”
20. WSDL description of a web services types defined in <xsd:schema> simple messages parts of messages interface specification operations of an interface input message output message binding of interface to protocols & encoding description of the binding for each operation service description URI and binding to port <definitions> <types></types> <message> <part></part> </message> <portType> <operation> <input> <output> </operation> </portType> <binding> <operation> </binding> <service> <port> </service> </definitions>
21. ASP.NET MVC 4 and the Web API: Building a REST Service from Start to Finish book
22. ASP.NET MVC 4 and the Web API: Building a REST Service from Start to Finish book
23. ASP.NET MVC 4 and the Web API: Building a REST Service from Start to Finish book
24. <?xml version="1.0" encoding="utf-8"?> <Tasks> <TaskInfo Id="1234" Status="Active" > <link rel="self" href="/api/tasks/1234" method="GET" /> <link rel="users" href="/api/tasks/1234/users" method="GET" /> <link rel="history" href="/api/tasks/1234/history" method="GET" /> <link rel="complete" href="/api/tasks/1234" method="DELETE" /> <link rel="update" href="/api/tasks/1234" method="PUT" /> </TaskInfo> <TaskInfo Id="0987" Status="Completed" > <link rel="self" href="/api/tasks/0987" method="GET" /> <link rel="users" href="/api/tasks/0987/users" method="GET" /> <link rel="history" href="/api/tasks/0987/history" method="GET" /> <link rel="reopen" href="/api/tasks/0987" method="PUT" /> </TaskInfo> </Tasks> /api/tasks
25. ASP.NET MVC 4 and the Web API: Building a REST Service from Start to Finish book
32. ASP.NET and Web Tools 2012.2 Update Adding a simple Test Client to ASP.NET Web API Help Page
35. Serialization Validation Deserialization Response Controller / Action Request HTTP/1.1 200 OK Content-Length: 95267 Content-Type: text/html | application/json Accept: text/html, application/xhtml+xml, application/xml
36. GlobalConfiguration.Configuration.Formatters
37. var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter; json.UseDataContractJsonSerializer = true;
38.  "opt-out" approach  "opt-in" approach public class Product { public string Name { get; set; } public decimal Price { get; set; } [JsonIgnore] public int ProductCode { get; set; } } [DataContract] public class Product { [DataMember] public string Name { get; set; } [DataMember] public decimal Price { get; set; } // omitted by default public int ProductCode { get; set; } }
39. public object Get() { return new { Name = "Alice", Age = 23, Pets = new List<string> { "Fido", "Polly", "Spot" } }; } public void Post(JObject person) { string name = person["Name"].ToString(); int age = person["Age"].ToObject<int>(); }
40. var xml = GlobalConfiguration.Configuration.Formatters.XmlFormatter; xml.UseXmlSerializer = true; The XmlSerializer class supports a narrower set of types than DataContractSerializer, but gives more control over the resulting XML. Consider using XmlSerializer if you need to match an existing XML schema.
43. config.Formatters.JsonFormatter .SerializerSettings .ReferenceLoopHandling = ReferenceLoopHandling.Ignore; The simple fix will make serializer to ignore the reference which will cause a loop. However, it has limitations:  The data loses the looping reference information  The fix only applies to JSON.net  The level of references can't be controlled if there is a deep reference chain
45. config.Formatters.JsonFormatter .SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Serialize; config.Formatters.JsonFormatter .SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects;
47. // Fix 3 [JsonObject(IsReference = true)] public class Category { public int Id { get; set; } public string Name { get; set; } // Fix 3 [JsonIgnore] [IgnoreDataMember] public virtual ICollection<Product> Products { get; set; } } [DataContract(IsReference = true)] public class Product { [Key] public int Id { get; set; } [DataMember] public string Name { get; set; } [DataMember] public virtual Category Category { get; set; } }
48. “the process of selecting the best representation for a given response when there are multiple representations available.”
49. public HttpResponseMessage GetProduct(int id) { var product = new Product() { Id = id, Name = "Gizmo", Price = 1.99M }; IContentNegotiator negotiator = this.Configuration .Services.GetContentNegotiator(); ContentNegotiationResult result = negotiator.Negotiate( typeof(Product), this.Request, this.Configuration.Formatters); if (result == null) { var response = new HttpResponseMessage(HttpStatusCode.NotAcceptable); throw new HttpResponseException(response)); } return new HttpResponseMessage() { Content = new ObjectContent<Product>( product, // What we are serializing result.Formatter, // The media formatter result.MediaType.MediaType // The MIME type ) }; }
51. public class ProductMD { [StringLength(50), Required] public string Name { get; set; } [Range(0, 9999)] public int Weight { get; set; } }
52.  [Required]  [Exclude]  [DataType]  [Range] [MetadataTypeAttribute( typeof( Employee.EmployeeMetadata ) )] public partial class Employee } internal sealed class EmployeeMetadata } [StringLength(60)] [RoundtripOriginal] public string AddressLine { get; set; } } }  [StringLength(60)]  [RegularExpression]  [AllowHtml]  [Compare]
53. public class ProductsController : ApiController { public HttpResponseMessage Post(Product product) { if ( ModelState.IsValid ) { // Do something with the product (not shown). return new HttpResponseMessage(HttpStatusCode.OK); } else { return new HttpResponseMessage(HttpStatusCode.BadRequest); } } }
54. public class ModelValidationFilterAttribute : ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext actionContext) { if (actionContext.ModelState.IsValid == false) { // Return the validation errors in the response body. var errors = new Dictionary<string, IEnumerable<string>>(); foreach ( var keyValue in actionContext.ModelState ) { errors[keyValue.Key] = keyValue.Value.Errors.Select(e => e.ErrorMessage); } actionContext.Response = actionContext .Request .CreateResponse(HttpStatusCode.BadRequest, errors); } } }
55. public class ModelValidationFilterAttribute : ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext actionContext) { if (actionContext.ModelState.IsValid == false) { // Return the validation errors in the response body. var errors = new Dictionary<string, IEnumerable<string>>(); foreach ( var keyValue in actionContext.ModelState ) { errors[keyValue.Key] = keyValue.Value.Errors.Select(e => e.ErrorMessage); } actionContext.Response = actionContext .Request .CreateResponse(HttpStatusCode.BadRequest, errors); } } } protected void Application_Start() { // ... GlobalConfiguration .Configuration .Filters.Add(new ModelValidationFilterAttribute()); }
59. var config = new HttpSelfHostConfiguration("http://localhost:8080"); config.Routes.MapHttpRoute( "API Default", "api/{controller}/{id}", new { id = RouteParameter.Optional }); using (HttpSelfHostServer server = new HttpSelfHostServer(config)) { server.OpenAsync().Wait(); Console.ReadLine(); }
63. http://www.asp.net/web-api/ Why I’m giving REST a rest Building Hypermedia Web APIs with ASP.NET Web API
65. eyalvardi.wordpress.com