PHP로 작성된 프록시

프록시는 클라이언트가 사용하는 실제 서비스 객체를 대신하는 객체를 제공하는 구조 디자인 패턴입니다. 프록시는 클라이언트 요청을 수신하고, 일부 작업(접근 제어, 캐싱 등)을 수행한 다음 요청을 서비스 객체에 전달합니다.

프록시 객체는 서비스 객체와 같은 인터페이스를 가지기 때문에 클라이언트에 전달되면 실제 객체와 상호교환이 가능합니다.

프록시에 대하여 더 자세히 알아보세요

복잡도:

인기도:

사용 사례들: 프록시 패턴은 대부분의 PHP 앱에서 일반적으로 발견되지 않습니다. 그러나 일부 특별한 경우에는 여전히 매우 유용할 수 있습니다. 클라이언트 코드를 변경하지 않고 기존 클래스의 객체에 몇 가지 추가 행동들을 추가해야 할 때 매우 유용합니다.

식별: 프록시들은 모든 실제 작업을 다른 객체에 위임합니다. 각 프록시 메서드는 프록시가 서비스 객체의 자식 클래스가 아닌 이상 최종적으로 서비스 객체를 참조해야 합니다.

개념적인 예시

이 예시는 프록시 디자인 패턴의 구조를 보여주고 다음 질문에 중점을 둡니다:

패턴은 어떤 클래스들로 구성되어 있나요?
이 클래스들은 어떤 역할을 하나요?
패턴의 요소들은 어떻게 서로 연관되어 있나요?

이 패턴의 구조를 배우면 실제 PHP 사용 사례를 기반으로 하는 다음 예시를 더욱 쉽게 이해할 수 있을 것입니다.

index.php: 개념적인 예시

<?php

namespace RefactoringGuru\Proxy\Conceptual;

/**
 * The Subject interface declares common operations for both RealSubject and the
 * Proxy. As long as the client works with RealSubject using this interface,
 * you'll be able to pass it a proxy instead of a real subject.
 */
interface Subject
{
    public function request(): void;
}

/**
 * The RealSubject contains some core business logic. Usually, RealSubjects are
 * capable of doing some useful work which may also be very slow or sensitive -
 * e.g. correcting input data. A Proxy can solve these issues without any
 * changes to the RealSubject's code.
 */
class RealSubject implements Subject
{
    public function request(): void
    {
        echo "RealSubject: Handling request.\n";
    }
}

/**
 * The Proxy has an interface identical to the RealSubject.
 */
class Proxy implements Subject
{
    /**
     * @var RealSubject
     */
    private $realSubject;

    /**
     * The Proxy maintains a reference to an object of the RealSubject class. It
     * can be either lazy-loaded or passed to the Proxy by the client.
     */
    public function __construct(RealSubject $realSubject)
    {
        $this->realSubject = $realSubject;
    }

    /**
     * The most common applications of the Proxy pattern are lazy loading,
     * caching, controlling the access, logging, etc. A Proxy can perform one of
     * these things and then, depending on the result, pass the execution to the
     * same method in a linked RealSubject object.
     */
    public function request(): void
    {
        if ($this->checkAccess()) {
            $this->realSubject->request();
            $this->logAccess();
        }
    }

    private function checkAccess(): bool
    {
        // Some real checks should go here.
        echo "Proxy: Checking access prior to firing a real request.\n";

        return true;
    }

    private function logAccess(): void
    {
        echo "Proxy: Logging the time of request.\n";
    }
}

/**
 * The client code is supposed to work with all objects (both subjects and
 * proxies) via the Subject interface in order to support both real subjects and
 * proxies. In real life, however, clients mostly work with their real subjects
 * directly. In this case, to implement the pattern more easily, you can extend
 * your proxy from the real subject's class.
 */
function clientCode(Subject $subject)
{
    // ...

    $subject->request();

    // ...
}

echo "Client: Executing the client code with a real subject:\n";
$realSubject = new RealSubject();
clientCode($realSubject);

echo "\n";

echo "Client: Executing the same client code with a proxy:\n";
$proxy = new Proxy($realSubject);
clientCode($proxy);

Output.txt: 실행 결과

Client: Executing the client code with a real subject:
RealSubject: Handling request.

Client: Executing the same client code with a proxy:
Proxy: Checking access prior to firing a real request.
RealSubject: Handling request.
Proxy: Logging the time of request.

실제 사례 예시

프록시들이 사용될 수 있는 방법은 무수히 많습니다: 캐싱, 로깅, 접근 제한, 초기화 지연 등. 이 예시는 프록시 패턴이 다운로더 객체의 결과를 캐싱하여 해당 객체의 성능을 향상하는 방법을 보여줍니다.

index.php: 실제 사례 예시

<?php

namespace RefactoringGuru\Proxy\RealWorld;

/**
 * The Subject interface describes the interface of a real object.
 *
 * The truth is that many real apps may not have this interface clearly defined.
 * If you're in that boat, your best bet would be to extend the Proxy from one
 * of your existing application classes. If that's awkward, then extracting a
 * proper interface should be your first step.
 */
interface Downloader
{
    public function download(string $url): string;
}

/**
 * The Real Subject does the real job, albeit not in the most efficient way.
 * When a client tries to download the same file for the second time, our
 * downloader does just that, instead of fetching the result from cache.
 */
class SimpleDownloader implements Downloader
{
    public function download(string $url): string
    {
        echo "Downloading a file from the Internet.\n";
        $result = file_get_contents($url);
        echo "Downloaded bytes: " . strlen($result) . "\n";

        return $result;
    }
}

/**
 * The Proxy class is our attempt to make the download more efficient. It wraps
 * the real downloader object and delegates it the first download calls. The
 * result is then cached, making subsequent calls return an existing file
 * instead of downloading it again.
 *
 * Note that the Proxy MUST implement the same interface as the Real Subject.
 */
class CachingDownloader implements Downloader
{
    /**
     * @var SimpleDownloader
     */
    private $downloader;

    /**
     * @var string[]
     */
    private $cache = [];

    public function __construct(SimpleDownloader $downloader)
    {
        $this->downloader = $downloader;
    }

    public function download(string $url): string
    {
        if (!isset($this->cache[$url])) {
            echo "CacheProxy MISS. ";
            $result = $this->downloader->download($url);
            $this->cache[$url] = $result;
        } else {
            echo "CacheProxy HIT. Retrieving result from cache.\n";
        }
        return $this->cache[$url];
    }
}

/**
 * The client code may issue several similar download requests. In this case,
 * the caching proxy saves time and traffic by serving results from cache.
 *
 * The client is unaware that it works with a proxy because it works with
 * downloaders via the abstract interface.
 */
function clientCode(Downloader $subject)
{
    // ...

    $result = $subject->download("http://example.com/");

    // Duplicate download requests could be cached for a speed gain.

    $result = $subject->download("http://example.com/");

    // ...
}

echo "Executing client code with real subject:\n";
$realSubject = new SimpleDownloader();
clientCode($realSubject);

echo "\n";

echo "Executing the same client code with a proxy:\n";
$proxy = new CachingDownloader($realSubject);
clientCode($proxy);

Output.txt: 실행 결과

Executing client code with real subject:
Downloading a file from the Internet.
Downloaded bytes: 1270
Downloading a file from the Internet.
Downloaded bytes: 1270

Executing the same client code with a proxy:
CacheProxy MISS. Downloading a file from the Internet.
Downloaded bytes: 1270
CacheProxy HIT. Retrieving result from cache.