Deployer is an open-source deployment tool for PHP projects — specifically designed to automate, standardize, and securely deploy applications like Laravel, Symfony, Magento, WordPress, or any custom PHP apps.

🚀 What Makes Deployer Special?

• It’s a CLI tool, written in PHP.

• You define your deployment process in a deploy.php configuration file with clearly defined tasks.

• It supports zero-downtime deployment using symbolic links (symlinks).

• It supports multi-environment deployments (e.g., staging, production).

🛠️ Typical Deployer Workflow

Install Deployer via Composer:

composer require deployer/deployer --dev

Generate a config template:

vendor/bin/dep init

Configure deploy.php, e.g., for Laravel:

host('my-server.com')
    ->set('deploy_path', '/var/www/myproject')
    ->set('branch', 'main');

task('deploy', [
    'deploy:prepare',
    'deploy:vendors',
    'artisan:migrate',
    'deploy:publish',
]);

Deploy your app:

vendor/bin/dep deploy production

🔁 What Happens Under the Hood?

Deployer:

• Connects to the server via SSH

• Clones your Git repo into a new release directory

• Installs Composer dependencies

• Runs custom tasks (e.g., php artisan migrate)

• Updates the symlink to point to the new release (current)

• Removes old releases if configured

📦 Benefits of Deployer

Laravel Octane is an official package for the Laravel framework that dramatically boosts application performance by running Laravel on high-performance application servers like Swoole or RoadRunner.

⚡ What Makes Laravel Octane Special?

Instead of reloading the Laravel framework on every HTTP request (as with traditional PHP-FPM setups), Octane keeps the application in memory, avoiding repeated bootstrapping. This makes your Laravel app much faster.

🔧 How Does It Work?

Laravel Octane uses persistent worker servers (e.g., Swoole or RoadRunner), which:

1. Bootstrap the Laravel application once,

2. Then handle incoming requests repeatedly without restarting the framework.

🚀 Benefits of Laravel Octane

RoadRunner is a high-performance PHP application server developed by Spiral Scout. It serves as a replacement for traditional PHP-FPM (FastCGI Process Manager) and offers a major performance boost by keeping your PHP application running persistently — especially useful with frameworks like Laravel or Symfony.

🚀 What Makes RoadRunner Special?

✅ Worker-Based Performance

• PHP scripts are not reloaded on every request. Instead, they run continuously in persistent worker processes (similar to Node.js or Swoole).

• This eliminates the need to re-bootstrap the framework on every request — resulting in significantly faster response times than with PHP-FPM.

✅ Built with Go

• RoadRunner is written in the programming language Go, which provides high concurrency, easy deployment, and great stability.

✅ Features

• Native HTTP server (with HTTPS, Gzip, CORS, etc.)

• PSR-7 and PSR-15 middleware support

• Supports:

  • Queues (e.g., Redis, RabbitMQ)

  • gRPC

  • WebSockets

  • Static file serving

  • Prometheus metrics

  • RPC between Go and PHP

• Hot reload support with a watch plugin

⚙️ How Does It Work?

1. RoadRunner starts PHP worker processes.

2. These workers load your full framework bootstrap once.

3. Incoming HTTP or gRPC requests are forwarded to the PHP workers.

4. The response is returned through the Go layer — fast and concurrent.

📦 Common Use Cases:

• Laravel + RoadRunner (instead of Laravel + PHP-FPM)

• High-traffic applications and APIs

• Microservices

• Real-time apps (e.g., using WebSockets)

• Low-latency, serverless-like services

📉 RoadRunner vs PHP-FPM

A Headless CMS (Content Management System) is a system where the backend (content management) is completely separated from the frontend (content presentation).

In detail:

Traditional CMS (e.g., WordPress):

• Backend and frontend are tightly coupled.

• You create content in the system and it's rendered directly using built-in themes and templates with HTML.

• Pros: All-in-one solution, quick to get started.

• Cons: Limited flexibility, harder to deliver content across multiple platforms (e.g., website + mobile app).

Headless CMS:

• Backend only.

• Content is accessed via an API (usually REST or GraphQL).

• The frontend (e.g., a React site, native app, or digital signage) fetches the content dynamically.

• Pros: Very flexible, ideal for multi-channel content delivery.

• Cons: Frontend must be built separately (requires more development effort).

Common use cases:

• Websites built with modern JavaScript frameworks (like React, Next.js, Vue)

• Mobile apps that use the same content as the website

• Omnichannel strategies: website, app, smart devices, etc.

Examples of Headless CMS platforms:

• Contentful

• Strapi

• Sanity

• Directus

• Prismic

• Storyblok (a hybrid with visual editing capabilities)

Storyblok is a user-friendly, headless Content Management System (CMS) that helps developers and marketing teams create, manage, and publish content quickly and efficiently. It offers a visual editing interface for real-time content design and is flexible with various frameworks and platforms. Its API-first architecture allows content to be delivered to any digital platform, making it ideal for modern web and app development.

Aspect-Oriented Programming (AOP) is a programming paradigm focused on modularizing cross-cutting concerns—aspects of a program that affect multiple parts of the codebase and don't fit neatly into object-oriented or functional structures.

💡 Goal:

Typical cross-cutting concerns include logging, security checks, error handling, transaction management, or performance monitoring. These concerns often appear in many classes and methods. AOP allows you to write such logic once and have it automatically applied where needed.

🔧 Key Concepts:

• Aspect: A module that encapsulates a cross-cutting concern.

• Advice: The actual code to be executed (e.g., before, after, or around a method call).

• Join Point: A point in the program flow where an aspect can be applied (e.g., method execution).

• Pointcut: A rule that defines which join points are affected (e.g., "all methods in class X").

• Weaving: The process of combining aspects with the main program code—at compile-time, load-time, or runtime.

🛠 Example (Java with Spring AOP):

@Aspect
public class LoggingAspect {
    @Before("execution(* com.example.service.*.*(..))")
    public void logBeforeMethod(JoinPoint joinPoint) {
        System.out.println("Calling method: " + joinPoint.getSignature().getName());
    }
}

This code automatically logs a message before any method in the com.example.service package is executed.

✅ Benefits:

• Improved modularity

• Reduced code duplication

• Clear separation of business logic and system-level concerns

❌ Drawbacks:

• Can reduce readability (the flow isn't always obvious)

• Debugging can become more complex

• Often depends on specific frameworks (e.g., Spring, AspectJ)

Design by Contract (DbC) is a concept in software development introduced by Bertrand Meyer. It describes a method to ensure the correctness and reliability of software by defining clear "contracts" between different components (e.g., methods, classes).

Core Principles of Design by Contract

In DbC, every software component is treated as a contract party with certain obligations and guarantees:

1. Preconditions
   Conditions that must be true before a method or function can execute correctly.
   → Responsibility of the caller.

2. Postconditions
   Conditions that must be true after the execution of a method or function.
   → Responsibility of the method/function.

3. Invariant (Class Invariant)
   Conditions that must always remain true throughout the lifetime of an object.
   → Responsibility of both the method and the caller.

Goal of Design by Contract

• Clear specification of responsibilities.

• More robust and testable software.

• Errors are detected early (e.g., through contract violations).

Example in Pseudocode

class BankAccount {
    private double balance;

    // Invariant: balance >= 0

    void withdraw(double amount) {
        // Precondition: amount > 0 && amount <= balance
        if (amount <= 0 || amount > balance) throw new IllegalArgumentException();

        balance -= amount;

        // Postcondition: balance has been reduced by amount
    }
}

Benefits

• Clear contracts reduce misunderstandings.

• Easier debugging, as violations are detected immediately.

• Supports defensive programming.

Drawbacks

• Requires extra effort to define contracts.

• Not directly supported by all programming languages (e.g., Java and C++ via assertions, Python with decorators; Eiffel supports DbC natively).

A daemon (pronounced like "day-mon", not like the English word "demon") is a background process that runs on a computer system—typically without direct user interaction.

Key characteristics of a daemon:

• Starts automatically during system boot.

• Runs continuously in the background.

• Performs tasks without user input.

• Listens for requests from other programs or network connections.

Examples:

• cron daemon: Executes scheduled tasks (e.g., daily backups).

• sshd: Handles incoming SSH connections.

• httpd or nginx: Web server daemons.

• cupsd: Manages print jobs.

Technical background:

• On Unix/Linux systems, daemon process names often end in "d" (e.g., httpd, systemd).

• Daemons are typically launched at system startup by init systems like systemd or init.

Origin of the term:

The word comes from Greek mythology, where a “daimon” was a guiding spirit or invisible force—aptly describing software that works quietly behind the scenes.

The "Happy Path" (also known as the "Happy Flow") refers to the ideal scenario in software development or testing where everything works as expected, no errors occur, and all inputs are valid.

Example:

Let’s say you’re developing a user registration form. The Happy Path would look like this:

1. The user enters all required information correctly (e.g., a valid email and secure password).

2. They click “Register.”

3. The system successfully creates an account.

4. The user is redirected to a welcome page.

➡️ No validation errors, no server issues, and no unexpected behavior.

What is the purpose of the Happy Path?

• Initial testing focus: Developers and testers often check the Happy Path first to make sure the core functionality works.

• Basis for use cases: In documentation or requirements, the Happy Path is typically the main scenario before covering edge cases.

• Contrasts with edge cases / error paths: Anything that deviates from the Happy Path (e.g., missing password, server error) is considered an "unhappy path" or "alternate flow."

In software development, a guard (also known as a guard clause or guard statement) is a protective condition used at the beginning of a function or method to ensure that certain criteria are met before continuing execution.

In simple terms:

A guard is like a bouncer at a club—it only lets valid input or states through and exits early if something is off.

Typical example (in Python):

def divide(a, b):
    if b == 0:
        return "Division by zero is not allowed"  # Guard clause
    return a / b

This guard prevents the function from attempting to divide by zero.

Benefits of guard clauses:

• Early exit on invalid conditions

• Improved readability by avoiding deeply nested if-else structures

• Cleaner code flow, as the "happy path" (normal execution) isn’t cluttered by edge cases

Examples in other languages:

JavaScript:

function login(user) {
  if (!user) return; // Guard clause
  // Continue with login logic
}

Swift (even has a dedicated guard keyword):

func greet(person: String?) {
  guard let name = person else {
    print("No name provided")
    return
  }
  print("Hello, \(name)!")
}