PHPers: Fetching data to entities which belong to many external sources, see: https://www.facebook.com/groups/223889134481096/permalink/337805749756100/ .

classes.php

<?php
namespace PHPers;

use GuzzleHttp\Client as GuzzleClient;
use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Input\InputArgument;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;

// Entities: Just a place to store runtime data

class Repository
    {
    private $id;
    private $name;
    private $url;

    public function __construct($name, $url) {}

    public function getId() {}
    public function getName() {}
    public function getUrl() {}
    }

class User
    {
    private $id;
    private $email;
    private $repositories = array();

    public function __construct($email) {}

    public function addRepository(Repository $repository) {}
    public function hasRepository(Repository $repository) {}

    public function getId() {}
    public function getEmail() {}
    public function getRepositories() {}
    }

// Services: Interact with external sources using proper connector

interface RepositoryHostInterface
    {
    public function fetchRepositoriesByEmail($email);
    }

class Github implements RepositoryHostInterface
    {
    private $guzzle;

    public function __construct(GuzzleClient $guzzle) {}

    public function fetchRepositoriesByEmail($email) {}
    }

class BitBucket implements RepositoryHostInterface
    {
    private $guzzle;

    public function __construct(GuzzleClient $guzzle) {}

    public function fetchRepositoriesByEmail($email) {}
    }

// Repositories: Management of application storage

class UserCommandRepository
    {
    public function persist(User $user) {}
    }

class UserQueryRepository
    {
    public function findById($id) {}
    public function findByEmail($email) {}
    }

// Application: Handle user actions and defer external requests to commands

class UserController
    {
    private $userCommandRepository;
    private $userQueryRepository;

    public function __construct(
        UserCommandRepository $userCommandRepository,
        UserQueryRepository $userQueryRepository) {}

    public function createAction()
        {
        $user = new User('user@host.tld');
        $this->userCommandRepository->persist($user);
        $this->queueCommand('user:repositories:fetch', array(
            'id' => $user->getId(),
            ));
        }

    public function viewAction($id)
        {
        return $this->render('view.twig', array(
            'user' => $this->userQueryRepository->findById($id),
            ));
        }
    }

// Command: Use services fetch data from external sources and put them in an application storage

class UserFetchRepositoriesCommand extends Command
    {
    private $github;
    private $bitbucket;
    private $userCommandRepository;
    private $userQueryRepository;

    public function __construct(
        Github $github,
        BitBucket $bitbucket,
        UserCommandRepository $userCommandRepository,
        UserQueryRepository $userQueryRepository) {}

    protected function configure()
        {
        $this
            ->setName('user:repositories:fetch')
            ->setDefinition(array(new InputArgument('id', InputArgument::REQUIRED, 'User ID')));
        }

    public function execute(InputInterface $input, OutputInterface $output)
        {
        $id = $input->getArgument('id');
        $user = $this->userQueryRepository->findById($id);

        $repositories = $this->github->fetchByEmail($user->getEmail());
        $output->writeln(sprintf('Found %s repositories!', count($repositories)));
        array_map(function(Repository $repository) use($user) {
            $user->addRepository($repository);
            }, $repositories);

        // same for bitbucket

        $this->userCommandRepository->persist($user);
        }
    }