What's the difference among app.use, app.run, app.map in Owin? When to use what?

 When dealing with a request we use IApplicationBuilder. And we have four methods available to interact with a request:

• Use
• Run
• Map
• MapWhen

These are called Request Delegates.

Use:

Adds a middleware to the application pipeline and it can either pass the request to next delegate or it can end the request (short- circuit request pipeline). It is the most commonly used method to interact with middleware. 

More simple (app.use inserts a middleware into the pipeline which requires you to call the next middleware by calling next.Invoke()).

 Run:

app.run inserts a middleware without a next, so it just runs.

Map: 

With app.map you can map paths, which get evaluated at runtime, per request, to run certain middleware only if the request path matches the pattern you mapped.

MapWhen:

Behaves almost the same as Map except that we can specify the detailed condition by using a HttpContext object. We could check for URL, headers, query strings, cookies, etc).

Thank you