自托管WebAPI请求两次

Question

I'm learning about self-hosted web api, owin/katana and I came with this example:

Source: http://pastebin.com/0hsiEsdP

I pasted it on pastebin because here I keep getting "your code is not formatted" even between code tags =\\

So, there's two middlewares in the pipeline, one for "logging" and the other to just write something as response.

When I execute it and open the url in browser, it prints the "logging" message twice, like this:

Server started [Request from ::1] [Request from ::1]

The question is: why it's executed twice if I did only one request ?

Thanks!

Answer 1

If you log the request uri, like this:

Console.WriteLine("[Request from {0} to {1}]", context.Request.RemoteIpAddress, context.Request.Uri);

You'll see that there are in fact two requests:

[Request from ::1 to http://localhost:8080/]
[Request from ::1 to http://localhost:8080/favicon.ico]

The second one is to get the little icon that is displayed in the browser address bar. Also, this is browser-dependant: firefox will try to get favicon.ico once, and then will issue just single requests. Chome is always trying to get the favicon.

For testing purpose, you can use Fiddler to peek the http traffic and see what's excatly going on. Also, you can use some tools to issue raw HTTP requests directly (Fiddler, Postman, wget), because browsers can do stuff that you don't need or want while testing (like getting the favicon, caching, etc).