📘 PART 6: PROFESSIONAL DEVELOPMENT AND DEPLOYMENT

🎯 General Objectives

Master professional software development processes and apply them to PHP projects.
Implement CI/CD systems to automate testing and deployment.
Understand and apply modern monitoring and logging techniques for PHP applications.
Optimize application performance through profiling tools and performance improvement techniques.
Prepare knowledge and skills necessary for interviews and career development in the PHP field.

🧑‍🏫 Lesson 26: Professional Software Development Process

Git Flow and Version Management

bash

# Install Git Flow
apt-get install git-flow

# Initialize Git Flow in repository
git flow init

# Work with feature branch
git flow feature start new-feature
# Develop feature...
git flow feature finish new-feature

# Work with release branch
git flow release start 1.0.0
# Prepare release...
git flow release finish '1.0.0'

# Hotfix for production issues
git flow hotfix start critical-bug
# Fix bug...
git flow hotfix finish critical-bug

Code Reviews and Pull Requests

php

<?php
// Example of code refactored after review

// Before review
function getData($id) {
    $db = new PDO('mysql:host=localhost;dbname=test', 'user', 'password');
    $stmt = $db->prepare("SELECT * FROM data WHERE id = ?");
    $stmt->execute([$id]);
    $result = $stmt->fetch(PDO::FETCH_ASSOC);
    return $result;
}

// After review - Applying dependency injection, error handling, and logging
class DataRepository {
    private $db;
    private $logger;

    public function __construct(PDO $db, LoggerInterface $logger) {
        $this->db = $db;
        $this->logger = $logger;
    }

    public function getData(int $id): ?array {
        try {
            $stmt = $this->db->prepare("SELECT * FROM data WHERE id = ?");
            $stmt->execute([$id]);
            return $stmt->fetch(PDO::FETCH_ASSOC) ?: null;
        } catch (PDOException $e) {
            $this->logger->error("Database error: " . $e->getMessage(), ['id' => $id]);
            throw new RepositoryException("Could not fetch data", 0, $e);
        }
    }
}
?>

Applying TDD (Test-Driven Development)

php

<?php
use PHPUnit\Framework\TestCase;

class UserServiceTest extends TestCase
{
    private $userRepository;
    private $userService;

    protected function setUp(): void
    {
        $this->userRepository = $this->createMock(UserRepository::class);
        $this->userService = new UserService($this->userRepository);
    }

    public function testRegisterUserWithValidData()
    {
        // Arrange
        $userData = [
            'name' => 'John Doe',
            'email' => '[email protected]',
            'password' => 'SecurePassword123'
        ];

        $this->userRepository->expects($this->once())
            ->method('create')
            ->with(
                $this->equalTo($userData['name']),
                $this->equalTo($userData['email']),
                $this->callback(function($password) use ($userData) {
                    return password_verify($userData['password'], $password);
                })
            )
            ->willReturn(1);

        // Act
        $result = $this->userService->register($userData);

        // Assert
        $this->assertEquals(1, $result);
    }

    public function testRegisterUserWithInvalidEmail()
    {
        // Arrange
        $userData = [
            'name' => 'John Doe',
            'email' => 'invalid-email',
            'password' => 'SecurePassword123'
        ];

        // Assert exception
        $this->expectException(ValidationException::class);

        // Act
        $this->userService->register($userData);
    }
}
?>

Applying DDD (Domain-Driven Design)

php

<?php
// Domain Layer: Entities & Value Objects
class User {
    private UserId $id;
    private string $name;
    private Email $email;
    private HashedPassword $password;

    public function __construct(UserId $id, string $name, Email $email, HashedPassword $password) {
        $this->id = $id;
        $this->name = $name;
        $this->email = $email;
        $this->password = $password;
    }

    public function changePassword(string $newPassword): void {
        $this->password = new HashedPassword($newPassword);
    }

    // Getters...
}

// Value Objects
class Email {
    private string $value;

    public function __construct(string $email) {
        if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
            throw new InvalidArgumentException("Invalid email address");
        }
        $this->value = $email;
    }

    public function __toString(): string {
        return $this->value;
    }
}

// Application Layer: Services
class UserService {
    private UserRepository $repository;

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

    public function registerUser(string $name, string $email, string $password): UserId {
        $user = new User(
            UserId::generate(),
            $name,
            new Email($email),
            new HashedPassword($password)
        );

        return $this->repository->save($user);
    }
}

// Infrastructure Layer: Repositories
interface UserRepository {
    public function save(User $user): UserId;
    public function findById(UserId $id): ?User;
}

class MySqlUserRepository implements UserRepository {
    private PDO $connection;

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

    public function save(User $user): UserId {
        // Implementation...
    }

    public function findById(UserId $id): ?User {
        // Implementation...
    }
}
?>

Workflow with Jira/Trello

Backlog:
- Create User Stories/Tasks.
- Estimate Story Points/Effort.
Sprint Planning:
- Select User Stories for sprint.
- Break down tasks.
Daily Standup:
- What did you do yesterday?
- What will you do today?
- Any blockers?
Sprint Review:
- Demo completed features.
- Get feedback.
Sprint Retrospective:
- What went well?
- What needs improvement?
- Actions for next sprint.

🧑‍🏫 Lesson 27: CI/CD for PHP Applications

Introduction to CI/CD

Continuous Integration (CI): Automatically verifying source code upon changes. Each commit triggers build and test.
Continuous Deployment (CD): Automatically deploying the application to production environment after CI completes.

yaml

# .github/workflows/php-ci.yml
name: PHP CI

on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main, develop]

jobs:
  build-test:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v3

      - name: Setup PHP
        uses: shivammathur/setup-php@v2
        with:
          php-version: "8.1"
          extensions: mbstring, intl, pdo_mysql
          coverage: xdebug

      - name: Validate composer.json and composer.lock
        run: composer validate --strict

      - name: Cache Composer packages
        uses: actions/cache@v3
        with:
          path: vendor
          key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
          restore-keys: ${{ runner.os }}-php-

      - name: Install dependencies
        run: composer install --prefer-dist --no-progress

      - name: Run code style check
        run: vendor/bin/phpcs

      - name: Run static analysis
        run: vendor/bin/phpstan analyse src tests

      - name: Run test suite
        run: vendor/bin/phpunit --coverage-clover coverage.xml

      - name: Upload coverage to Codecov
        uses: codecov/codecov-action@v3
        with:
          file: ./coverage.xml

Configuring PHPUnit in Project

php

<?php
// phpunit.xml.dist
?>

xml

<?xml version="1.0" encoding="UTF-8"?>
<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.5/phpunit.xsd"
         colors="true"
         bootstrap="vendor/autoload.php">
  <testsuites>
    <testsuite name="Unit Tests">
      <directory>tests/Unit</directory>
    </testsuite>
    <testsuite name="Integration Tests">
      <directory>tests/Integration</directory>
    </testsuite>
    <testsuite name="Feature Tests">
      <directory>tests/Feature</directory>
    </testsuite>
  </testsuites>

  <coverage processUncoveredFiles="true">
    <include>
      <directory suffix=".php">src</directory>
    </include>
    <report>
      <clover outputFile="coverage.xml"/>
      <html outputDirectory="coverage-report"/>
    </report>
  </coverage>

  <php>
    <env name="APP_ENV" value="testing"/>
    <env name="DB_CONNECTION" value="sqlite"/>
    <env name="DB_DATABASE" value=":memory:"/>
  </php>
</phpunit>

Code Quality Tools

php

<?php
// phpcs.xml
?>

xml

<?xml version="1.0" encoding="UTF-8"?>
<ruleset name="PHP_CodeSniffer">
    <description>PHP Coding Standards</description>

    <!-- Scan these files -->
    <file>src</file>
    <file>tests</file>

    <!-- Show progress -->
    <arg value="p"/>
    <arg name="colors"/>

    <!-- Use PSR-12 -->
    <rule ref="PSR12"/>

    <!-- Específic rules -->
    <rule ref="Generic.Files.LineLength">
        <properties>
            <property name="lineLimit" value="120"/>
            <property name="absoluteLineLimit" value="120"/>
        </properties>
    </rule>
</ruleset>

PHP Static Analysis Tool (PHPStan)

php

<?php
// phpstan.neon
?>

yaml

parameters:
  level: 8
  paths:
    - src
    - tests
  excludePaths:
    - vendor/*
  checkMissingIterableValueType: false
  checkGenericClassInNonGenericObjectType: false

Automated Deployment with Laravel Forge/Envoyer

Laravel Forge Deployment Process

Connect to repository (GitHub/GitLab/Bitbucket).
When a new commit is pushed to the deploy branch (main/master):
- Pull changes from repository.
- Run composer install --no-dev.
- Run npm ci && npm run build (if frontend exists).
- Run migrations: php artisan migrate --force.
- Reload PHP-FPM.
- Clear cache: php artisan cache:clear.
- Restart queues: php artisan queue:restart.

Or custom deploy script configuration:

bash

composer install --no-dev
php artisan migrate --force
php artisan optimize
php artisan config:cache
php artisan route:cache
php artisan view:cache

Zero-Downtime Deployment

Zero-Downtime Deployment Process:

Preparation:
- Create new release directory.
- Copy new code to release directory.
Install dependencies:
- composer install --no-dev
Configuration:
- Copy/symlink config files and .env.
Optimization:
- php artisan optimize
- php artisan config:cache
- php artisan route:cache
- php artisan view:cache
Migrations:
- php artisan migrate --force (Ensure migrations do not cause downtime)
Update symlink:
- Point "current" symlink to new release. (This is an "atomic switch" - almost instant and no downtime)
Restart services:
- php-fpm reload
- php artisan queue:restart
Cleanup:
- Keep X most recent releases, delete old ones.

🧑‍🏫 Lesson 28: Monitoring and Logging PHP Applications

Monolog in PHP

php

<?php
// Logging configuration with Monolog
use Monolog\Logger;
use Monolog\Handler\StreamHandler;
use Monolog\Handler\SlackHandler;
use Monolog\Formatter\JsonFormatter;
use Monolog\Processor\IntrospectionProcessor;
use Monolog\Processor\WebProcessor;

// Create main logger
$logger = new Logger('app');

// Add file handler
$fileHandler = new StreamHandler('logs/app.log', Logger::DEBUG);
$fileHandler->setFormatter(new JsonFormatter());
$logger->pushHandler($fileHandler);

// Add Slack handler for critical errors
$slackHandler = new SlackHandler(
    'slack-token',
    '#errors',
    'ErrorBot',
    true,
    null,
    Logger::ERROR
);
$logger->pushHandler($slackHandler);

// Add processors to log extra info
$logger->pushProcessor(new IntrospectionProcessor());
$logger->pushProcessor(new WebProcessor());

// Use logger
$logger->info('User logged in', ['user_id' => 123]);
$logger->error('Payment failed', [
    'user_id' => 123,
    'amount' => 99.95,
    'error_code' => 'CARD_DECLINED'
]);
?>

Monitoring with ELK Stack (Elasticsearch, Logstash, Kibana)

yml

# docker-compose.yml for ELK stack
version: "3"

services:
  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch:7.17.0
    environment:
      - discovery.type=single-node
      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
    ports:
      - "9200:9200"
    volumes:
      - elasticsearch-data:/usr/share/elasticsearch/data

  logstash:
    image: docker.elastic.co/logstash/logstash:7.17.0
    depends_on:
      - elasticsearch
    volumes:
      - ./logstash-config:/usr/share/logstash/pipeline
    ports:
      - "5000:5000"

  kibana:
    image: docker.elastic.co/kibana/kibana:7.17.0
    depends_on:
      - elasticsearch
    ports:
      - "5601:5601"
    environment:
      ELASTICSEARCH_HOSTS: http://elasticsearch:9200

volumes:
  elasticsearch-data:

Logstash Configuration

conf

# logstash-config/logstash.conf
input {
  file {
    type => "php-logs"
    path => "/var/log/php/app.log"
    codec => "json"
  }
  tcp {
    port => 5000
    codec => "json"
  }
}

filter {
  if [type] == "php-logs" {
    grok {
      match => { "message" => "%{COMBINEDAPACHELOG}" }
    }
    date {
      match => [ "timestamp", "dd/MMM/yyyy:HH:mm:ss Z" ]
    }
  }
}

output {
  elasticsearch {
    hosts => ["elasticsearch:9200"]
    index => "php-logs-%{+YYYY.MM.dd}"
  }
}

Monitoring with Prometheus and Grafana

php

<?php
// Use Prometheus PHP Client
// composer require promphp/prometheus_client_php

use Prometheus\CollectorRegistry;
use Prometheus\Storage\Redis;

// Connect to Redis instance
$adapter = new Redis(['host' => 'redis', 'port' => 6379]);
$registry = new CollectorRegistry($adapter);

// Count requests
$counter = $registry->getOrRegisterCounter('app', 'requests_total', 'Total request count', ['endpoint']);
$counter->incBy(1, [$_SERVER['REQUEST_URI']]);

// Measure execution time
$histogram = $registry->getOrRegisterHistogram(
    'app',
    'request_duration_seconds',
    'Request duration in seconds',
    ['endpoint'],
    [0.01, 0.05, 0.1, 0.5, 1, 2, 5]
);

$start = microtime(true);
// Process request...
$duration = microtime(true) - $start;
$histogram->observe($duration, [$_SERVER['REQUEST_URI']]);

// Set gauge for database connections
$gauge = $registry->getOrRegisterGauge('app', 'db_connections', 'Current database connections');
$gauge->set(DB::getConnectionCount());
?>

Prometheus Metrics Endpoint

php

<?php
// metrics.php - Endpoint for Prometheus scrape metrics

// Header
header('Content-Type: text/plain; version=0.0.4');

// Get registry
$adapter = new Prometheus\Storage\Redis(['host' => 'redis', 'port' => 6379]);
$registry = new Prometheus\CollectorRegistry($adapter);

// Output metrics
$renderer = new Prometheus\RenderTextFormat();
echo $renderer->render($registry->getMetricFamilySamples());
?>

Exception Handling and Error Tracking

php

<?php
// Set custom error handler
set_error_handler(function($severity, $message, $file, $line) {
    if (!(error_reporting() & $severity)) {
        // Error not in error_reporting
        return;
    }
    throw new ErrorException($message, 0, $severity, $file, $line);
});

// Set exception handler
set_exception_handler(function(Throwable $exception) {
    global $logger;

    // Log exception
    $logger->error('Uncaught exception: ' . $exception->getMessage(), [
        'exception' => [
            'class' => get_class($exception),
            'message' => $exception->getMessage(),
            'code' => $exception->getCode(),
            'file' => $exception->getFile(),
            'line' => $exception->getLine(),
            'trace' => $exception->getTraceAsString(),
        ]
    ]);

    // Notify Slack for critical errors
    if ($exception instanceof FatalErrorException) {
        notifySlack($exception);
    }

    // Display user-friendly error in production
    if (getenv('APP_ENV') === 'production') {
        http_response_code(500);
        echo json_encode([
            'error' => 'Server Error',
            'message' => 'Something went wrong. Our team has been notified.'
        ]);
    } else {
        // Display detailed error in development
        http_response_code(500);
        echo '<h1>Error</h1>';
        echo '<p>' . htmlspecialchars($exception->getMessage()) . '</p>';
        echo '<pre>' . htmlspecialchars($exception->getTraceAsString()) . '</pre>';
    }
});

// Integrate with Error Tracking service like Sentry
// composer require sentry/sdk
Sentry\init([
    'dsn' => 'https://[email protected]/0',
    'environment' => getenv('APP_ENV'),
    'release' => '1.0.0',
]);

try {
    // Code might cause exception
    processOrder($orderId);
} catch (Throwable $exception) {
    Sentry\captureException($exception);
    // Handle exception
}
?>

🧑‍🏫 Lesson 29: Performance Tuning and Profiling

Profiling Tools for PHP

php

<?php
// Use Xdebug profiling
// php.ini configuration
/*
[xdebug]
xdebug.mode=profile
xdebug.output_dir=/tmp/xdebug
xdebug.profiler_output_name=cachegrind.out.%p
*/

// Use Tideways XHProf
// composer require tideways/php-xhprof-extension

// Start profiling
tideways_xhprof_enable(TIDEWAYS_XHPROF_FLAGS_CPU | TIDEWAYS_XHPROF_FLAGS_MEMORY);

// Code to profile
$result = complexCalculation();

// Stop profiling and save results
$profile_data = tideways_xhprof_disable();
file_put_contents(
    '/tmp/profile_data_' . uniqid() . '.json',
    json_encode($profile_data)
);
?>

Blackfire.io Integration

Integrating Blackfire.io

Install Blackfire Agent and PHP Probe following instructions.

Use Blackfire SDK to profile specific code.

bash

composer require blackfire/php-sdk

php

<?php
\BlackfireProbe::getMainInstance()->enable();

// Code to profile
$result = complexCalculation();

\BlackfireProbe::getMainInstance()->disable();

// 3. Web UI for interacting with dashboard
// Use Chrome extension to trigger profile
?>

Database Query Optimization

php

<?php
// Analyze and optimize queries

// 1. Enable MySQL Slow Query Log
// my.cnf configuration
/*
[mysqld]
slow_query_log = 1
slow_query_log_file = /var/log/mysql/mysql-slow.log
long_query_time = 1
*/

// 2. Analyze query with EXPLAIN
$stmt = $pdo->prepare("EXPLAIN SELECT * FROM users JOIN orders ON users.id = orders.user_id WHERE users.status = ?");
$stmt->execute(['active']);
$explainResults = $stmt->fetchAll(PDO::FETCH_ASSOC);
print_r($explainResults);

// 3. Optimize queries
// Bad query
$stmt = $pdo->prepare("SELECT * FROM products WHERE category_id = ? ORDER BY price DESC");

// Optimized query - only fetch needed data
$stmt = $pdo->prepare("SELECT id, name, price FROM products WHERE category_id = ? ORDER BY price DESC");

// 4. Use indexes
// Create index
$pdo->exec("CREATE INDEX idx_products_category_price ON products (category_id, price)");

// 5. Avoid N+1 query problem
// Bad approach - N+1 queries
$users = $pdo->query("SELECT * FROM users LIMIT 100")->fetchAll();
foreach ($users as $user) {
    $orders = $pdo->prepare("SELECT * FROM orders WHERE user_id = ?");
    $orders->execute([$user['id']]);
    // Process orders...
}

// Good approach - 1 query with JOIN
$stmt = $pdo->query(
    "SELECT users.*, orders.*
     FROM users
     LEFT JOIN orders ON users.id = orders.user_id
     WHERE users.id IN (SELECT id FROM users LIMIT 100)"
);
?>

Caching Strategies

php

<?php
// 1. Install and connect Redis
$redis = new Redis();
$redis->connect('redis', 6379);

// 2. Caching data
function getUserData($userId) {
    global $redis, $pdo;

    // Cache key
    $cacheKey = "user:{$userId}:data";

    // Try to get from cache
    $cachedData = $redis->get($cacheKey);
    if ($cachedData) {
        return json_decode($cachedData, true);
    }

    // Cache miss - fetch from database
    $stmt = $pdo->prepare("SELECT * FROM users WHERE id = ?");
    $stmt->execute([$userId]);
    $userData = $stmt->fetch(PDO::FETCH_ASSOC);

    // Store in cache with TTL (1 hour)
    $redis->setex($cacheKey, 3600, json_encode($userData));

    return $userData;
}

// 3. Caching query results
function getActiveProducts($categoryId) {
    global $redis, $pdo;

    // Cache key
    $cacheKey = "category:{$categoryId}:active_products";

    // Try to get from cache
    $cachedData = $redis->get($cacheKey);
    if ($cachedData) {
        return json_decode($cachedData, true);
    }

    // Cache miss - fetch from database
    $stmt = $pdo->prepare(
        "SELECT id, name, price, stock
         FROM products
         WHERE category_id = ? AND active = 1"
    );
    $stmt->execute([$categoryId]);
    $products = $stmt->fetchAll(PDO::FETCH_ASSOC);

    // Store in cache with TTL (5 minutes)
    $redis->setex($cacheKey, 300, json_encode($products));

    return $products;
}

// 4. Cache invalidation when data changes
function updateProduct($productId, $data) {
    global $redis, $pdo;

    // Update in database
    $stmt = $pdo->prepare(
        "UPDATE products SET name = ?, price = ?, stock = ? WHERE id = ?"
    );
    $stmt->execute([$data['name'], $data['price'], $data['stock'], $productId]);

    // Get category for cache invalidation
    $stmt = $pdo->prepare("SELECT category_id FROM products WHERE id = ?");
    $stmt->execute([$productId]);
    $product = $stmt->fetch(PDO::FETCH_ASSOC);

    // Invalidate cache
    $redis->del("category:{$product['category_id']}:active_products");
    $redis->del("product:{$productId}:data");
}
?>

Load Testing with k6

// load-test.js - k6 script
import http from "k6/http";
import { sleep, check } from "k6";

export const options = {
  stages: [
    { duration: "30s", target: 50 }, // Ramp-up to 50 users over 30s
    { duration: "1m", target: 50 }, // Stay at 50 users for 1 minute
    { duration: "30s", target: 100 }, // Ramp-up to 100 users
    { duration: "1m", target: 100 }, // Stay at 100 users for 1 minute
    { duration: "30s", target: 0 }, // Ramp-down to 0 users
  ],
  thresholds: {
    http_req_duration: ["p(95)<500"], // 95% of requests should finish within 500ms
    "http_req_duration{status:200}": ["max<600"], // Maximum duration of 200 responses should be below 600ms
  },
};

export default function () {
  // Test homepage
  const homeRes = http.get("https://example.com/");
  check(homeRes, {
    "homepage status is 200": (r) => r.status === 200,
    "homepage load time < 500ms": (r) => r.timings.duration < 500,
  });

  sleep(1);

  // Test API endpoint
  const apiRes = http.get("https://example.com/api/products");
  check(apiRes, {
    "api status is 200": (r) => r.status === 200,
    "api response is JSON": (r) =>
      r.headers["Content-Type"].includes("application/json"),
  });

  sleep(2);
}

Best Practices for Performance

Use Opcode Cache (OPcache)

Improves PHP code execution speed by storing precompiled bytecode.
Configure OPcache in php.ini

ini

[opcache]
opcache.enable=1
opcache.memory_consumption=128
opcache.interned_strings_buffer=8
opcache.max_accelerated_files=10000
opcache.validate_timestamps=0 # in production
opcache.save_comments=1
opcache.fast_shutdown=1
opcache.enable_file_override=1
opcache.jit=1255
opcache.jit_buffer_size=100M

Avoid eager loading of unnecessary code
- Use composer autoloader optimization
bash
```
composer dump-autoload --optimize
```
Use connection pooling for database
- Use PgBouncer or ProxySQL to reduce overhead when creating new connections.
- Configure PgBouncer
ini
```
[databases]
mydb = host=localhost dbname=mydb user=myuser password=mypassword
```
Optimize file size
- Minify & Combine CSS/JS for frontend.
- Enable HTTP/2 to reduce latency.
- Enable Gzip compression to reduce response size.
Use CDN for static assets.

Use queues for heavy processing.

Example: email, file processing, report generation.
Use RabbitMQ or Redis for queue processing.

php

// Publish job to queue
function queueEmailJob($emailData) {
    $connection = new AMQPStreamConnection('localhost', 5672, 'guest', 'guest');
    $channel = $connection->channel();

    $channel->queue_declare('email_queue', false, true, false, false);

    $msg = new AMQPMessage(
        json_encode($emailData),
        ['delivery_mode' => AMQPMessage::DELIVERY_MODE_PERSISTENT]
    );

    $channel->basic_publish($msg, '', 'email_queue');

    $channel->close();
    $connection->close();
}

// Worker to process queue
function startEmailWorker() {
    $connection = new AMQPStreamConnection('localhost', 5672, 'guest', 'guest');
    $channel = $connection->channel();

    $channel->queue_declare('email_queue', false, true, false, false);

    $callback = function($msg) {
        $emailData = json_decode($msg->body, true);

        try {
            // Process email
            sendEmail($emailData);
            $msg->delivery_info['channel']->basic_ack($msg->delivery_info['delivery_tag']);
        } catch (Exception $e) {
            // Log error and reject message
            $msg->delivery_info['channel']->basic_reject($msg->delivery_info['delivery_tag'], false);
        }
    };

    $channel->basic_qos(null, 1, null);
    $channel->basic_consume('email_queue', '', false, false, false, false, $callback);

    while(count($channel->callbacks)) {
        $channel->wait();
    }
}
?>

🧑‍🏫 Lesson 30: PHP Interview Preparation and Career Development

Common PHP Interview Questions

PHP Basics:
- Difference between "==" and "==="?
- Data types in PHP?
- Magic methods in PHP?
- What are superglobals?
- Scope in PHP (global/local)?
OOP in PHP:
- What is encapsulation, inheritance, polymorphism?
- Interface vs Abstract class?
- Type hinting in PHP?
- What are Traits in PHP and when to use them?
- Namespaces and their purpose?
Design Patterns:
- What is Singleton pattern and when to use?
- MVC pattern and role of each component?
- Factory pattern and when to apply?
- What is Repository pattern?
- Dependency Injection and benefits?
Database and SQL:
- What are prepared statements and why use them?
- MySQL vs PostgreSQL - when to use which?
- Indexing in database?
- INNER JOIN vs LEFT JOIN?
- What are transactions and when are they needed?
Security:
- Cross-site scripting (XSS) and prevention?
- SQL Injection and prevention?
- What is CSRF and how to protect against it?
- Password security in PHP?
- Session security best practices?
Modern PHP:
- What is Composer and how to manage dependencies?
- What are PSR standards?
- New features in PHP 8?
- Async programming in PHP?
- Docker and containerization in PHP?
Testing:
- Unit testing vs Integration testing?
- What is PHPUnit and how to use it?
- Mocking in testing?
- What is TDD and why apply it?
Performance:
- How to optimize PHP performance?
- Caching strategies in PHP?
- What is Opcache and how to configure it?
- JIT in PHP 8?
- When to use queues?

Portfolio and Open Source

Building a PHP Developer Portfolio:

Projects to include in portfolio:
- CRUD application using MVC framework.
- RESTful API or GraphQL API.
- Application with authentication/authorization.
- Project using complex database relationships.
- Third-party API integration.
Open Source Contributions:
- Find suitable PHP repositories on GitHub.
- Start with "good first issues".
- Contribute documentation.
- Fix simple bugs.
- Create small PHP packages.
Technical Blog:
- Write about PHP concepts you just learned.
- Share case studies from projects.
- Tutorials on new PHP technologies.
- Analysis of performance and security issues.

Career Path in PHP

Junior PHP Developer (0-2 years):
- Solid grasp of basic PHP and OOP.
- Familiar with at least one framework (Laravel/Symfony).
- Understand basic database and SQL.
- Basic knowledge of HTML, CSS, JavaScript.
Mid-level PHP Developer (2-5 years):
- Deep understanding of framework.
- Design patterns and architectural patterns.
- Unit testing and CI/CD.
- Performance optimization.
- REST APIs and API design.
- Caching strategies.
- Professional Git workflow.
Senior PHP Developer (5+ years):
- System design and architecture.
- Microservices and distributed systems.
- Infrastructure and DevOps.
- Database optimization and scaling.
- Security best practices.
- Mentoring and code reviews.
- Cross-functional collaboration.
Tech Lead / Architect:
- Guide system architecture.
- Select technology and technical roadmap.
- Manage technical debt.
- Train and develop team.
- Participate in hiring process.
- Communicate with stakeholders.
Specialized paths:
- DevOps Engineer
- Security Specialist
- Performance Engineer
- API Architect
- Open Source Contributor

Technical Interview Preparation

Coding challenges:
- Practice on LeetCode/HackerRank.
- Implement basic algorithms.
- Solve design pattern problems.
Whiteboard/system design:
- Practice designing databases.
- Draw architecture diagrams.
- Explain trade-offs in decisions.
Mock interviews:
- Pair programming with colleagues.
- Online mock interviews.
- Review and improve from feedback.
Prepare questions for interviewers:
- Tech stack and challenges.
- Engineering culture and processes.
- Career growth and mentorship.
- Work-life balance.

php

<?php
// Example: Common Coding Challenge
function isPalindrome(string $str): bool {
    $str = preg_replace('/[^a-z0-9]/i', '', strtolower($str));
    return $str === strrev($str);
}

function fizzbuzz(int $n): void {
    for ($i = 1; $i <= $n; $i++) {
        if ($i % 3 === 0 && $i % 5 === 0) {
            echo "FizzBuzz\n";
        } elseif ($i % 3 === 0) {
            echo "Fizz\n";
        } elseif ($i % 5 === 0) {
            echo "Buzz\n";
        } else {
            echo $i . "\n";
        }
    }
}
?>

Keeping Up with PHP Ecosystem:

php

<?php
/*
Follow and update PHP knowledge:

1. PHP RFC and GitHub:
   - https://wiki.php.net/rfc
   - https://github.com/php/php-src

2. Blogs and newsletters:
   - PHP Weekly
   - PHP Annotated Monthly
   - Laravel News
   - Symfony Blog

3. Podcasts:
   - PHP Roundtable
   - Laravel Podcast
   - Full Stack Radio
   - PHP Architects Radio

4. Conferences:
   - PHP[tek]
   - Laracon
   - Symfony Con
   - PHP UK Conference

5. Online courses and platforms:
   - Laracasts
   - Symfonycasts
   - PHP The Right Way

6. Twitter accounts and social media:
   - @official_php
   - @laravelphp
   - @symfony
   - @nikita_ppv
*/
?>

🧪 FINAL COMPREHENSIVE PROJECT: Build a Complete E-Learning System

Requirements

System Architecture:
- Apply microservices architecture.
- Use Docker to containerize services.
- Implement CI/CD pipeline.
Core Modules:
- Authentication Service (registration, login, user management).
- Course Service (create courses, manage content).
- Enrollment Service (enroll in courses, track progress).
- Media Service (upload and stream lecture videos).
- Analytics Service (statistics, reports).
- Payment Service (course payments).
Technical Requirements:
- Backend API: PHP 8.1+, Laravel/Symfony.
- Database: MySQL/PostgreSQL.
- Cache: Redis.
- Message Queue: RabbitMQ.
- Frontend: Vue.js/React.
- Authentication: JWT/OAuth2.
- API Gateway: Kong/Nginx.
- Logging: ELK Stack.
- Monitoring: Prometheus/Grafana.
- Testing: PHPUnit, Jest.
Features:
- Registration/Login (email, social).
- User/Instructor dashboard.
- Create and manage courses.
- Upload and manage lecture videos.
- Discussion forum for each course.
- Online payment.
- Reporting and data analysis.
- Integrated notifications (email, push).
- Admin panel to manage the whole system.
Advanced Features:
- Real-time chat with instructors.
- Video conferencing for live classes.
- Recommendation system for courses.
- Mobile-friendly responsive design.
- Progressive Web App capabilities.
- Multilingual support.
- Content caching and CDN integration.

Project Structure

text

e-learning-platform/
├── docker-compose.yml
├── api-gateway/
│   ├── Dockerfile
│   └── src/
├── auth-service/
│   ├── Dockerfile
│   ├── src/
│   └── database/
├── course-service/
│   ├── Dockerfile
│   ├── src/
│   └── database/
├── enrollment-service/
│   ├── Dockerfile
│   ├── src/
│   └── database/
├── media-service/
│   ├── Dockerfile
│   ├── src/
│   └── storage/
├── analytics-service/
│   ├── Dockerfile
│   ├── src/
│   └── database/
├── payment-service/
│   ├── Dockerfile
│   ├── src/
│   └── database/
├── frontend/
│   ├── Dockerfile
│   └── src/
├── admin-panel/
│   ├── Dockerfile
│   └── src/
├── message-broker/
│   └── rabbitmq/
├── cache/
│   └── redis/
├── monitoring/
│   ├── prometheus/
│   └── grafana/
└── logging/
    ├── elasticsearch/
    ├── logstash/
    └── kibana/

Evaluation Criteria

Code Quality:
- Clean code and best practices.
- Proper documentation.
- Appropriate design patterns usage.
- Code consistency and style standards (PSR).
Architecture:
- Microservices communication.
- System resilience.
- Scaling capabilities.
- Service boundaries.
Testing:
- Unit tests (minimum 70% coverage).
- Integration tests.
- E2E tests for critical flows.
Performance:
- Optimization techniques.
- Caching strategy.
- Response time (<300ms for APIs).
Security:
- Authentication/Authorization.
- Data protection.
- Input validation.
- CSRF/XSS prevention.
CI/CD:
- Automated testing.
- Deployment pipeline.
- Environment configurations.
- Monitoring integration.
Documentation:
- API documentation.
- System architecture diagrams.
- Setup and deployment instructions.
- User guides.

📘 PART 6: PROFESSIONAL DEVELOPMENT AND DEPLOYMENT ​

🎯 General Objectives ​

🧑‍🏫 Lesson 26: Professional Software Development Process ​

Git Flow and Version Management ​

Code Reviews and Pull Requests ​

Applying TDD (Test-Driven Development) ​

Applying DDD (Domain-Driven Design) ​

Workflow with Jira/Trello ​

🧑‍🏫 Lesson 27: CI/CD for PHP Applications ​

Introduction to CI/CD ​

Configuring PHPUnit in Project ​

Code Quality Tools ​

PHP Static Analysis Tool (PHPStan) ​

Automated Deployment with Laravel Forge/Envoyer ​

Zero-Downtime Deployment ​

🧑‍🏫 Lesson 28: Monitoring and Logging PHP Applications ​

Monolog in PHP ​

Monitoring with ELK Stack (Elasticsearch, Logstash, Kibana) ​

Logstash Configuration ​

Monitoring with Prometheus and Grafana ​

Prometheus Metrics Endpoint ​

Exception Handling and Error Tracking ​

🧑‍🏫 Lesson 29: Performance Tuning and Profiling ​

Profiling Tools for PHP ​

Blackfire.io Integration ​

Database Query Optimization ​

Caching Strategies ​

Load Testing with k6 ​

Best Practices for Performance ​

🧑‍🏫 Lesson 30: PHP Interview Preparation and Career Development ​

Common PHP Interview Questions ​

Portfolio and Open Source ​

Career Path in PHP ​

Technical Interview Preparation ​

🧪 FINAL COMPREHENSIVE PROJECT: Build a Complete E-Learning System ​

Requirements ​

Project Structure ​

Evaluation Criteria ​

📘 PART 6: PROFESSIONAL DEVELOPMENT AND DEPLOYMENT

🎯 General Objectives

🧑‍🏫 Lesson 26: Professional Software Development Process

Git Flow and Version Management

Code Reviews and Pull Requests

Applying TDD (Test-Driven Development)

Applying DDD (Domain-Driven Design)

Workflow with Jira/Trello

🧑‍🏫 Lesson 27: CI/CD for PHP Applications

Introduction to CI/CD

Configuring PHPUnit in Project

Code Quality Tools

PHP Static Analysis Tool (PHPStan)

Automated Deployment with Laravel Forge/Envoyer

Zero-Downtime Deployment

🧑‍🏫 Lesson 28: Monitoring and Logging PHP Applications

Monolog in PHP

Monitoring with ELK Stack (Elasticsearch, Logstash, Kibana)

Logstash Configuration

Monitoring with Prometheus and Grafana

Prometheus Metrics Endpoint

Exception Handling and Error Tracking

🧑‍🏫 Lesson 29: Performance Tuning and Profiling

Profiling Tools for PHP

Blackfire.io Integration

Database Query Optimization

Caching Strategies

Load Testing with k6

Best Practices for Performance

🧑‍🏫 Lesson 30: PHP Interview Preparation and Career Development

Common PHP Interview Questions

Portfolio and Open Source

Career Path in PHP

Technical Interview Preparation

🧪 FINAL COMPREHENSIVE PROJECT: Build a Complete E-Learning System

Requirements

Project Structure

Evaluation Criteria