The UrlMap class takes an array mapping paths to apps and dispatches accordingly. This class is insertable into a Middleware Stack Builder, like stack/builder.

Install with Composer:

$ curl -sS https://getcomposer.org/installer | php
$ php composer.phar require chh/url-map:~1.0@dev

Let's say we have a Silex app and want to map a blogging app which implements HttpKernelInterface at the sub path /blog:

<?php

use Symfony\Component\HttpFoundation\Request;
use Silex\Application;

$app = new Application();
$app->get('/', function () {
    return "Main Application!";
});

$blog = new Application();
$blog->get('/', function () {
    return "This is the blog!";
});

$map = [
    "/blog" => $blog
];

$app = (new Stack\Builder())
    ->push('Stack\UrlMap', $map)
    ->resolve($app);

$request = Request::createFromGlobals();

$response = $app->handle($request);
$response->send();

$app->terminate($request, $response);

If you now navigate to /blog you should see This is the blog! in your browser.

The UrlMap overrides SCRIPT_NAME, SCRIPT_FILENAME and PHP_SELF to point at the mapped path. This also makes sure that the path is stripped from the path info.

This also means that apps which use the Symfony Routing component for Routing and URL Generation don't need any adaptions.

Apps using other means for routing should prepend the return value of the request's getBaseUrl() method to generated URLs. The URL Map also sets a stack.url_map.prefix request attribute, which can be used if you don't want to rely on the request base URL.