Update documentation home page

docs/source/index.rst

@@ -1,7 +1,7 @@
 WellRESTed
 ==========
 
-WellRESTed is a library for creating RESTful APIs and websites in PHP that provides abstraction for HTTP messages, a powerful middleware system, and a flexible router.
+WellRESTed is a library for creating RESTful APIs and websites in PHP that provides abstraction for HTTP messages, a powerful handler and middleware system, and a flexible router.
 
 Features
 --------
@@ -13,6 +13,11 @@ Request and response messages are built to the interfaces standardized by PSR-7_
 
 The message abstractions facilitate working with message headers, status codes, variables extracted from the path, message bodies, and all the other aspects of requests and responses.
 
+PSR-15 Handler interfaces
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Handlers and middleware may implement the interfaces define by the PSR-15_ standard.
+
 Router
 ^^^^^^
 
@@ -47,54 +52,75 @@ The site will also provide an ``X-example: hello world`` using dedicated middlew
 
     <?php
 
+    use Psr\Http\Message\ResponseInterface;
+    use Psr\Http\Message\ServerRequestInterface;
+    use Psr\Http\Server\MiddlewareInterface;
+    use Psr\Http\Server\RequestHandlerInterface;
+    use WellRESTed\Message\Response;
     use WellRESTed\Message\Stream;
     use WellRESTed\Server;
 
-    require_once "vendor/autoload.php";
-
-    // Build some middleware. We'll register these with a server below.
-    // We're using callables to fit this all in one example, but these
-    // could also be classes implementing WellRESTed\MiddlewareInterface.
-
-    // Set the status code and provide the greeting as the response body.
-    $hello = function ($request, $response, $next) {
+    require_once 'vendor/autoload.php';
 
+    // Create a handler that will construct and return a response. We'll 
+    // register this handler with a server and router below.
+    class HelloHandler implements RequestHandlerInterface
+    {
+        public function handle(ServerRequestInterface $request): ResponseInterface
+        {
             // Check for a "name" attribute which may have been provided as a
             // path variable. Use "world" as a default.
             $name = $request->getAttribute("name", "world");
 
             // Set the response body to the greeting and the status code to 200 OK.
-        $response = $response->withStatus(200)
+            $response = (new Response(200))
                 ->withHeader("Content-type", "text/plain")
                 ->withBody(new Stream("Hello, $name!"));
 
-        // Propagate to the next middleware, if any, and return the response.
-        return $next($request, $response);
+            // Return the response.
+            return $response;
+        }
+    }
 
-    };
+    // Create middleware that will add a custom header to every response.
+    class CustomerHeaderMiddleware implements MiddlewareInterface
+    {
+        public function process(
+            ServerRequestInterface $request,
+            RequestHandlerInterface $handler
+        ): ResponseInterface {
+
+            // Delegate to the next handler in the chain to obtain a response.
+            $response = $handler->handle($request);
 
-    // Add a header to the response.
-    $headerAdder = function ($request, $response, $next) {
             // Add the header.
             $response = $response->withHeader("X-example", "hello world");
-        // Propagate to the next middleware, if any, and return the response.
-        return $next($request, $response);
-    };
+
+            // Return the altered response.
+            return $response;
+        }
+    }
 
     // Create a server
     $server = new Server();
 
-    // Start each request-response cycle by dispatching the header adder.
-    $server->add($headerAdder);
+    // Add the header adding middleware to the server first so that it will
+    // forward requests on to the router.
+    $server->add(new CustomerHeaderMiddleware());
 
-    // The header adder will propagate to this router, which will dispatch the
-    // $hello middleware, possibly with a {name} variable.
-    $server->add($server->createRouter()
-        ->register("GET", "/hello", $hello)
-        ->register("GET", "/hello/{name}", $hello)
-    );
+    // Create a router to map methods and endpoints to handlers.
+    $router = $server->createRouter();
 
-    // Read the request from the client, dispatch middleware, and output.
+    $handler = new HelloHandler();
+    // Register a route to the handler without a variable in the path.
+    $router->register('GET', '/hello', $handler);
+    // Register a route that reads a "name" from the path.
+    // This will make the "name" request attribute available to the handler.
+    $router->register('GET', '/hello/{name}', $handler);
+
+    $server->add($router);
+
+    // Read the request from the client, dispatch, and output.
     $server->respond();
 
 Contents
@@ -116,6 +142,7 @@ Contents
    web-server-configuration
 
 .. _PSR-7: http://www.php-fig.org/psr/psr-7/
+.. _PSR-15: http://www.php-fig.org/psr/psr-15/
 .. _middleware: middleware.html
 .. _router: router.html
 .. _URI Templates: uri-templates.html