Proxy Pattern

The Proxy Pattern is a structural design pattern that provides a placeholder or representative object to control access to another object.

Instead of accessing the real object directly, the client communicates through a proxy.

The proxy can:

• Control access

• Add security

• Add caching

• Delay object creation

• Log requests

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Real Life Example

Think about an ATM Card 💳

You do not directly access the bank server.

Flow:

Client
   ↓
Proxy
   ↓
Real Service

The ATM card:

• Verifies PIN

• Checks permissions

• Controls access

This is Proxy Pattern.

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Structure

Client
   ↓
Proxy
   ↓
Real Service

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Laravel / PHP Example

Scenario

We are building an image loader.

Large images are expensive to load.

We use a proxy to:

• Delay loading

• Load only when needed

This is called Virtual Proxy.

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Step 1: Subject Interface

interface Image
{
    public function display();
}

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Step 2: Real Object

Heavy object.

class RealImage implements Image
{
    protected string $filename;

    public function __construct(string $filename)
    {
        $this->filename = $filename;

        $this->loadFromDisk();
    }

    protected function loadFromDisk()
    {
        echo "Loading {$this->filename} from disk...\n";
    }

    public function display()
    {
        echo "Displaying {$this->filename}\n";
    }
}

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Step 3: Proxy Class

class ProxyImage implements Image
{
    protected ?RealImage $realImage = null;

    protected string $filename;

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

    public function display()
    {
        if ($this->realImage === null) {
            $this->realImage = new RealImage($this->filename);
        }

        $this->realImage->display();
    }
}

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Step 4: Usage

$image = new ProxyImage('large-photo.jpg');

echo "Image will load only when needed\n";

$image->display();

$image->display();

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Output

Image will load only when needed

Loading large-photo.jpg from disk...
Displaying large-photo.jpg
Displaying large-photo.jpg

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What Happened?

First Call

display()

Proxy creates the real object.

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Second Call

Object already exists.

No reload needed ✅

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Why Use Proxy?

Without proxy:

$image = new RealImage('large-photo.jpg');

Large file loads immediately ❌

Even if never used.

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With Proxy

$image = new ProxyImage('large-photo.jpg');

Loads only when required ✅

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Types of Proxy Pattern

Type	Purpose
Virtual Proxy	Lazy loading
Protection Proxy	Access control
Remote Proxy	Remote service communication
Caching Proxy	Store previous results
Logging Proxy	Monitor requests

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Protection Proxy Example

class AdminProxy
{
    public function access($role)
    {
        if ($role !== 'admin') {
            return "Access Denied";
        }

        return "Welcome Admin";
    }
}

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Real Laravel Examples

1. Lazy Loading in Eloquent

$user->posts

Laravel loads relation only when needed.

Proxy-like behavior.

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2. Cache Facade

Cache::remember()

Acts like caching proxy.

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3. Middleware

Middleware controls access before request reaches controller.

Proxy behavior.

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Advantages

1. Lazy Loading

Load expensive objects only when needed.

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2. Security Control

Can restrict unauthorized access.

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3. Performance Optimization

Caching and delayed initialization improve performance.

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4. Logging & Monitoring

Track access transparently.

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Proxy vs Decorator

Proxy	Decorator
Controls access	Adds behavior
May delay execution	Enhances functionality
Focus on control	Focus on extension

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Proxy vs Facade

Proxy	Facade
Controls one object	Simplifies many objects
Same interface as real object	Different simplified interface
Access management	Complexity reduction

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When to Use Proxy Pattern

Use Proxy Pattern when:

✅ Object creation is expensive ✅ Lazy loading is needed ✅ Access control is required ✅ Logging/caching needed ✅ Remote object communication exists

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Short Interview Definition

The Proxy Pattern provides a surrogate or placeholder object that controls access to another object.