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Would like to integrate a legacy application with a Symfony 2 application - replacing more and more parts of the old application with Symfony components. The approach I would take is using the Symfony 2 container in the legacy application getting the services that are already configured for the Symfony 2 application. The first services I would like to use are the session and the security context.

Questions:

  • Is this feasible?
  • How do I get the configured service container?

More info in the legacy application: The typical PHP mess: Single PHP files, as "controllers" (checking $_GET and $_POST for different execution paths). Each page includes init.php which sets up autoloading, database connection etc. The session management has its own class (which i would like to replace), the data is retrieved through calls to static methods (!) of database objects.

chiborg
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  • I can't say if it's possible or not... Of course it is, but is it worth it ? To implement the service container, considerate you'll have to implement Symfony2 kernel, that is the framework's core. – AlterPHP Apr 16 '12 at 08:50
  • Without any information on the structure of the legacy app it's impossible to answer this question, except to say that it probably isn't possible for non-OOP code without a major rewrite. – GordonM Apr 16 '12 at 09:09
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    I did something like this. I used regular S2 to get to a S2 controller action. From the controller I then called my legacy initialization code and then called it's controllers. Very much a hack but it worked okay. I don't think you will have much luck getting a properly configured S2 session object without doing something like this. – Cerad Apr 16 '12 at 12:55

2 Answers2

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Using Symfony's DIC as a standalone component is possible but you'd have to do many things "manually" (as you're not planning on using full Symfony Framework from the very beginning). You'll probably won't get much of using DIC with all that legacy stuff.

If you want to go this path I'd consider choosing another component first (like HttpFoundation and HttpKernel).

As @Cerad suggested you might wrap your legacy code in Symfony. Have a look at IngewikkeldWrapperBundle bundle. You can't use it as is but it might give you some ideas.

There's a third way.

You can decide to implement every new feature in a Symfony app. Than, you can make that both legacy and Symfony apps coexist. On a server level (i.e. Nginx), you might proxy legacy URLs to the legacy app and all the migrated URLs to a Symfony2 app. In my case this scenario was the best option and proved to be working. However, we were committed to abandon legacy app development (so every new feature or change had to be developed in a Symfony2 app).

Edit: here's how you could boot the Symfony kernel in a legacy app and dispatch an event (which is needed for the firewall):

$kernel = new \AppKernel('dev', true);
$kernel->boot();

$request = Request::createFromGlobals();
$request->attributes->set('is_legacy', true);
$request->server->set('SCRIPT_FILENAME', 'app.php');

$container = $kernel->getContainer();
$container->enterScope('request');
$container->get('request_stack')->push($request);
$container->set('request', $request);

$event = new GetResponseEvent($kernel, $request, HttpKernelInterface::MASTER_REQUEST);
$eventDispatcher = $container->get('event_dispatcher');
$eventDispatcher->dispatch('kernel.request', $event);
Jakub Zalas
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I believe you can access the container instance from your legacy application like this

$kernel = new AppKernel('prod', true);
$kernel->loadClassCache();
$kernel->boot();
$request = Request::createFromGlobals();
$container = $kernel->getContainer();
$sc = $container->get('security.context');
Sethunath K M
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  • Yes, that works. I added a line calling the "boot" method which initializes the container. However, I still can't use the security.context since it's heavily dependent on the symfony MVC setup. – chiborg Apr 17 '12 at 13:36
  • You can access security context like this $container->get('security.context') – Sethunath K M Apr 17 '12 at 13:42
  • Yes, but I've tried to call `getToken` or `isGranted` and got an `AuthenticationCredentialsNotFoundException`. So I assume using the security context will only work if you initialize your request objects and routing with Symfony - which I can't at the moment. – chiborg Apr 17 '12 at 14:34
  • The documentation says that "AuthenticationCredentialsNotFoundException is thrown when an authentication is rejected because no Token is available." . – Sethunath K M Apr 17 '12 at 14:45
  • I know. And as far as I see the token is only initialized when a request is funneled through the Symfony request handling mechanism. The Security bundle registers some event handlers for that, but the event handlers are never fired since I don't use the Symfony request handling. – chiborg Apr 17 '12 at 15:08