Module: import HTTP

Responder#

The Responder is a simple protocol defining the behavior of objects that can accept a Request and return a Response. Most notably in Vapor, it is the core API endpoint that connects the Droplet to the Server. Let’s look at the definition:

public protocol Responder {
    func respond(to request: Request) throws -> Response
}

The responder protocol is most notably related to Droplet and it’s relationship with a server. Average users will not likely interact with it much.

Simple#

Of course, Vapor provides some conveniences for this, and in practice, we will often call:

try drop.run()

Manual#

As we just mentioned, the Vapor Droplet itself conforms to Responder, connecting it to the Server. This means if we wanted to serve our droplet manually, we could do:

let server = try Server<TCPServerStream, Parser<Request>, Serializer<Response>>(port: port)
try server.start(responder: droplet)  { error in
    print("Got error: \(error)")
}

Advanced#

We can conform our own objects to Responder and pass them to Servers. Let’s look at an example:

final class Responder: HTTP.Responder {
    func respond(to request: Request) throws -> Response {
        let body = "Hello World".makeBody()
        return Response(body: body)
    }
}

This only returns "Hello World" for every request, it’s most commonly going to be linked with a router of some type.

final class Responder: HTTP.Responder {
    let router: Router = ...

    func respond(to request: Request) throws -> Response {
        return try router.route(request)
    }
}

We’ll then pass this responder to a server and let it go.

let server = try Server<TCPServerStream, Parser<Request>, Serializer<Response>>(port: port)

print("visit http://localhost:\(port)/")
try server.start(responder: Responder()) { error in
    print("Got error: \(error)")
}

This can be used as a jumping off point for applications looking to implement features manually.

Client#

The HTTP.Client is itself a Responder although, instead of handling the Request itself, it passes it on to the underlying URI.