要 Self Hosting Web API，首先需要安裝 Microsoft.AspNet.WebApi.SelfHost 套件。

建立 HttpSelfHostConfiguration 並指定要監聽的位置。

var config =new HttpSelfHostConfiguration("http://localhost:32767");

設定 HttpSelfHostConfiguration，像是 URL Routing 資訊。

config.Routes.MapHttpRoute("API","{controller}/{action}/{id}",
new{ });

如果要被 Host 的 Web API 在其它的組件，這邊也可建立一個實作 IAssembliesResolver 的 SelfHostAssemblyResolve 類型。

public class SelfHostAssemblyResolver : IAssembliesResolver
{
#region Properties
///
/// Gets the path.
///
///
/// The path.
///
public string Path { get; private set ; }
#endregion Properties

#region Constructors
///
/// Initializes a new instance of the class.
///
/// The path.
public SelfHostAssemblyResolver(string path)
{
this.Path = path;
}
#endregion Constructors

#region Methods
///
/// Returns a list of assemblies available for the application.
///
///
/// An of assemblies.
///
public ICollection GetAssemblies()
{
List assemblies = new List();

assemblies.Add( Assembly.LoadFrom(Path));

return assemblies;
}
#endregion Methods
}

帶入外部組件位置建立對應的物件，然後將服務中的 IAssembliesResolver 用該物件取代即可。

config.Services.Replace(typeof(IAssembliesResolver),new SelfHostAssemblyResolver("AgileSlot.API.dll"));

接著建立 HttpSelfHostServer，建立時帶入前面所建立的 HttpSelfHostConfiguration

當開始要使用服務時，叫用 HttpSelfHostServer.OpenAsync 啟動 Web API 服務

httpServer.OpenAsync();

當不在需要服務時，叫用 HttpSelfHostServer.CloseAsync 中止 Web API 服務

httpServer.CloseAsync();

整個程式寫起來會像下面這樣：

var config =new HttpSelfHostConfiguration("http://localhost:32767");
config.Routes.MapHttpRoute("API","{controller}/{action}/{id}",
new{ });

config.Services.Replace(typeof(IAssembliesResolver),newSelfHostAssemblyResolver("AgileSlot.API.dll"));

using(var httpServer =new HttpSelfHostServer(config))
{
httpServer.OpenAsync().Wait();
Console.WriteLine("Web API host started...");
string line =null;
do
{
line =Console.ReadLine();
}
while(line !="exit");
httpServer.CloseAsync().Wait();
}