Run your legacy applications within Zend Framework 2.

Since rewriting your legacy application from scratch to a ZF2 application could be nearly impossible due to time, effort, and resources, i was searching for a way to migrate a legacy application to a ZF2 application.

A great article by Chris Abernethy described a way on how to run your legacy application within ZF1, so I migrated this HowTo to a small ZF2 module, to be able to run a legacy application within ZF2.

While running your legacy application within a ZF2 application it is possible to slowly migrate an existing application to ZF2 by leaving your old application (nearly - see "Adjust your legacy Application") untouched and build new modules with the power of ZF2.
By adding a simple wrapper (see "Using ZF2 within your legacy application") you could also use the new modules within your legacy application.

Install through composer

{
    "require" : {
        "maglnet/magl-legacy-application" : "*"
    }
}

Enable the module within your ZF2 application.config.php

    'modules' => array(
        'Application',
        'MaglLegacyApplication',
    ),

Copy the provided file data/magl-zf2-legacy-wrapper.php to your public/ folder.
Copy the provided file data/.htaccess to your publix folder.
Copy your legacy Application to your public/ folder.

Your legacy application should now run within ZF2. :)

For any SEO optimized route within your legacy application, add a route to the zend router that routes to legacy controller and remove the mod_rewrite rules from your .htaccess

return array(
    'router' => array(
        'routes' => array(
            // example for transferring mod rewrite rules to zf2 routes
            'legacy-seo-calendar' => array(
                'type' => 'Zend\Mvc\Router\Http\Regex',
                'options' => array(
                    'regex'    => '/calendar/(?<foo>.+)',
                    'defaults' => array(
                        'controller' => 'MaglLegacyApplication\Controller\Legacy',
                        'action'     => 'index',
                        'script'     => 'index-already-seo-optimized.php',
                    ),
                    'spec' => '/',
                ),
            ),
        ),
    ),
);

There are several cases in which your legacy application won't run without additional adjustments, here are some of them:

Using relative paths for require, require_once or includes will possibly fail now, since ZF2 will do a chdir() to the ZF2's application root. So you will need to adjust your paths to match the new root.

Example:

include '../lib/somelib.php';

should be changed to:

include __DIR__ . '/../lib/somelib.php';

Because of mod_rewrite rules, SCRIPT_FILENAME and SCRIPT_NAME won't be your real script anymore. If you use these variables, you need to adjust these places within your legacy application:

Example:

$script_filename = $_SERVER['SCRIPT_FILENAME'];
$script_name     = $_SERVER['SCRIPT_NAME'];

should be changed to:

use MaglLegacyApplication\Application\MaglLegacy;
$legacy          = MaglLegacy::getInstance();
$script_filename = $legacy->getLegacyScriptFilename();
$script_name     = $legacy->getLegacyScriptName();

use MaglLegacyApplication\Application\MaglLegacy;
$application = MaglLegacy::getInstance()->getApplication();
$yourService = $application->getServiceManager()->get('YourService');

from wherever you are within your legacy application, it is possible to bypass your legacy applications controller code and send a response to the ZF2 Controller wrapper. This response will then be handled like within a normal ZF2 controller.

use MaglLegacyApplication\Application\MaglLegacy;
$application = MaglLegacy::getInstance()->getApplication();
$application->getEventManager()->getSharedManager()->attach('*', MaglLegacy::EVENT_SHORT_CIRCUIT_RESPONSE, function(Event $e){
    $response = new \Zend\Http\Response();
    $response->setStatusCode(404);
    $response->setContent('not found');
    $e->stopPropagation(true);
    return $response;
});

If you have questions or problems regarding this module just open an issue or, even better, solve it and open a pull request. 👍