Let's talk about the proxy mode in PHP (forward proxy and reverse proxy)

In the previous article " A Brief Talk on the Responsibility Chain Model in PHP" we introduced the responsibility chain model in PHP. This article will take you to understand the agency model in the PHP design pattern.

The profession of agent has another name in China, real estate broker and insurance broker. In fact, this profession is called real estate agent or insurance agent abroad. As the name suggests, they help us handle work in these professional fields that are unfamiliar to most of us. The same is true for the proxy mode. At the same time, this article will also briefly introduce forward proxy and reverse proxy.

Gof class diagram and explanation

GoF definition: Provide a proxy for other objects to control access to this object

GoF class diagram

##Code implementation

interface Subject
{
    public function Request();
}

class RealSubject implements Subject
{
    function Request()
    {
        echo "真实的操作", PHP_EOL;
    }
}

class Proxy implements Subject
{
    private $realSubject;

    public function __construct()
    {
        $this->realSubject = new RealSubject();
    }

    public function Request()
    {
        echo "代理的操作", PHP_EOL;
        $this->realSubject->Request();
    }
}

$proxy = new Proxy();
$proxy->Request();

The implementation of the proxy mode is actually very simple. You may often use it inadvertently.
Please pay attention to the difference between the proxy mode and decorators and adapters. In addition, the template method pattern is also very similar to it.
Decorator, generally decorates the object, and the method behavior will be increased, mainly modifying the object
Adapter, generally will change the method behavior, the purpose is to maintain the unity of the interface but get different implementations
Template method pattern, we will talk about it later, as long as you know here, the template method is to combine the methods of calling subclasses in the abstract class
The proxy mode has several forms: remote proxy (for example: Third-party interface SDK), virtual agent (for example: asynchronous loading of pictures), protection agent & intelligent guidance (for example: permission protection), and the most common agent implemented by our code is actually to let the agent class replace the operation of the real class

Full code: https://github.com/zhangyue0503/designpatterns-php/blob/master/12.proxy/source/proxy.php

Example

SMS sending class diagram

Full source code: https://github.com/zhangyue0503/designpatterns-php /blob/master/12.proxy/source/proxy-msg.php

<?php

interface SendMessage
{
    public function Send();
}

class RealSendMessage implements SendMessage
{
    public function Send()
    {
        echo &#39;短信发送中...&#39;, PHP_EOL;
    }
}

class ProxySendMessage implements SendMessage
{
    private $realSendMessage;

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

    public function Send()
    {
        echo &#39;短信开始发送&#39;, PHP_EOL;
        $this->realSendMessage->Send();
        echo &#39;短信结束发送&#39;, PHP_EOL;
    }
}

$sendMessage = new ProxySendMessage(new RealSendMessage());
$sendMessage->Send();

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Instructions

The example is very simple, it is still a normal proxy Implementation, here we talk about forward proxy and reverse proxy
• Usually what we call scientific Internet access (fanqiang) is forward proxy. We use software or configure the proxy gateway ourselves to access the Internet. In fact, we use The request is sent to the designated gateway, and then this gateway visits other websites on our behalf. This kind of proxy specified and selected by us is the forward proxy.
• Most PHPers are relatively aware of reverse proxy. After all, Nginx is now It has replaced Apache and become the standard configuration of PHP. When we visit a website, certain paths or domain names are not necessarily on this server. They are directly proxied on the server to other servers or even other people's sites. Those of us who browse the website don’t know this. This kind of situation where we are inexplicably proxyed without knowing it is a reverse proxy. Generally, it is a necessary knowledge in the backend operation and maintenance of services!

Original address: https://juejin.cn/post/6844903959988011016

Author: Hardcore Project Manager

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