Run Owin app in ASP .NET MVC 4

Question

I have an ASP .NET MVC 4 project where I am trying to integrate an Owin app to run only for a specific path, so all requests starting with owin-api/* will be handled by the Owin pipeline Microsoft.Owin.Host.SystemWeb.OwinHttpHandler and the other requests by the MVC pipeline System.Web.Handlers.TransferRequestHandler

To accomplish this, I have the following:

In the Web.config

<appSettings>
    <add key="owin:appStartup" value="StartupServer.Startup"/>
</appSettings>   
<system.webServer>
        <handlers>
            <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
            <remove name="OPTIONSVerbHandler" />
            <remove name="TRACEVerbHandler" />
            <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
            <add  name="Owin" verb="*" path="owin-api/*" type="Microsoft.Owin.Host.SystemWeb.OwinHttpHandler, Microsoft.Owin.Host.SystemWeb" />
        </handlers>
</system.webServer>

The startup class:

namespace StartupServer
{

    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            app.Run(context =>
            {
                return context.Response.WriteAsync("Owin API");
            });
        }
    }
}

However "Owin API" is now the outoput for every request. How can I tell IIS to use the OwinHttpHandler only when the path owin-api/* as specified in the Web.config?

Have you tried adding the handler under <location path="owin-api">? — haim770
@haim770 unfortunately it doesn't work. The problem is Owin appear to be taking precedence over all other http handlers — Sow OBM

DavidG DavidG · Accepted Answer · 2016-11-03T16:24:34

app.Run() inserts into the OWIN pipeline a middleware which does not have a next middleware reference. So you probably want to replace it with app.Use().

You could detect the URL and base your logic on that. For example:

app.Use(async (context, next) =>
{
    if (context.Request.Uri.AbsolutePath.StartsWith("/owin-api"))
    {
        await context.Response.WriteAsync("Owin API");
    }
    await next();
});

Run Owin app in ASP .NET MVC 4

1 Answers