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Beyond MVC: Data, Context, and Interaction in CakePHP

Written by Yevgeny on December 15, 2024
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This article is part of the CakeDC Advent Calendar 2024 (December 15th 2024)

Introduction to the Creator of DCI

The Data-Context-Interaction (DCI) architectural pattern was introduced by Trygve Reenskaug, a Norwegian computer scientist and software engineer. Reenskaug is well known for his contributions to object-oriented programming and design. He is also famous for the development of the Model-View-Controller (MVC) design pattern, which has become a foundational concept in software architecture, especially in web development.

Other artciles of the series

The Emergence of DCI

Reenskaug introduced the DCI pattern as a way to address some of the limitations he observed in traditional object-oriented programming. The DCI pattern aims to separate the concerns of data (the model), the context in which that data is used (the interaction), and the interactions themselves (the roles that objects play in specific scenarios). This separation allows for more maintainable, understandable, and flexible code, making it easier to adapt to changing business requirements.

Classic Implementation

The classic example used to introduce the DCI pattern is the money transfer scenario. This example show how DCI separates the roles of data, context, and interaction, allowing for a clearer understanding of how objects interact in a system. By modeling the transfer of funds between accounts, we can see how the roles of TransferSource and TransferDestination are defined, encapsulating the behaviors associated with withdrawing and depositing money. This separation enhances code maintainability and readability, making it easier to adapt to changing business requirements.

classDiagram
    class TransferSource {
        +BigDecimal balance
        +updateBalance(newBalance: BigDecimal): Unit
        +withdraw(amount: BigDecimal): Unit
        +canWithdraw(amount: BigDecimal): Boolean
    }

    class TransferDestination {
        +BigDecimal balance
        +updateBalance(newBalance: BigDecimal): Unit
        +deposit(amount: BigDecimal): Unit
    }

    class Account {
        +String id
        +BigDecimal balance
    }

    class MoneyTransfer {
        +Account source
        +Account destination
        +BigDecimal amount
        +execute(): Unit
    }

    Account ..|> TransferSource : implements
    Account ..|> TransferDestination : implements
    MoneyTransfer --> TransferSource : uses
    MoneyTransfer --> TransferDestination : uses

In the money transfer example, we typically have two accounts: a source account from which funds are withdrawn and a destination account where the funds are deposited. The DCI pattern allows us to define the behaviors associated with these roles separately from the data structure of the accounts themselves. This means that the logic for transferring money can be encapsulated in a context, such as a MoneyTransfer class, which orchestrates the interaction between the source and destination accounts. By doing so, we achieve a more modular and flexible design that can easily accommodate future changes or additional features, such as transaction logging or validation rules.

sequenceDiagram
    participant M as Main
    participant S as Source Account
    participant D as Destination Account
    participant MT as MoneyTransfer

    M->>S: new Account("1", 1000) with TransferSource
    M->>D: new Account("2", 500) with TransferDestination
    M->>MT: new MoneyTransfer(source, destination, 100)
    M->>MT: execute()
    MT->>S: canWithdraw(100)
    alt Source can withdraw
        S-->>MT: true
        MT->>S: withdraw(100)
        S->>S: updateBalance(900)
        MT->>D: deposit(100)
        D->>D: updateBalance(600)
    else Source cannot withdraw
        S-->>MT: false
        MT->>M: throw Exception("Source cannot withdraw")
    end

First, I want to show the classic implementation in Scala. By Trygve the language is well suited for this pattern, as traits implementation allow to define the roles and the context in a very clean way and mixins traits into the objects allow explicitely define the roles of the each object.

trait TransferSource {
  def balance: BigDecimal
  def updateBalance(newBalance: BigDecimal): Unit

  def withdraw(amount: BigDecimal): Unit = {
    require(amount > 0, "Amount must be positive")
    require(balance >= amount, "Insufficient funds")

    updateBalance(balance - amount)
  }

  def canWithdraw(amount: BigDecimal): Boolean =
    amount > 0 && balance >= amount
}

trait TransferDestination {
  def balance: BigDecimal
  def updateBalance(newBalance: BigDecimal): Unit

  def deposit(amount: BigDecimal): Unit = {
    require(amount > 0, "Amount must be positive")
    updateBalance(balance + amount)
  }
}

case class Account(id: String, var balance: BigDecimal)

class MoneyTransfer(
    source: Account with TransferSource,
    destination: Account with TransferDestination,
    amount: BigDecimal
) {
  def execute(): Unit = {
    require(source.canWithdraw(amount), "Source cannot withdraw")

    source.withdraw(amount)
    destination.deposit(amount)
  }
}

object Main extends App {
  val source = new Account("1", 1000) with TransferSource
  val dest = new Account("2", 500) with TransferDestination

  val transfer = new MoneyTransfer(source, dest, 100)
  transfer.execute()
}

Basic PHP Implementation

Some languages don't have the same level of flexibility and expressiveness as Scala. Most obvious approach is class wrapper definition for actor roles. I see both pros and cons of this approach. The pros are that it's very easy to understand and implement. The cons are that it's not very flexible and it's not very easy to extend and require additional boilerplate code.

Here is the sequence diagram of the implementation:

sequenceDiagram
    participant MT as MoneyTransfer
    participant S as MoneySource
    participant D as MoneyDestination
    participant Source as Source Account
    participant Destination as Destination Account

    MT->>S: bind(Source)
    S->>Source: validatePlayer(Source)
    alt Player is valid
        S-->>MT: Player bound successfully
    else Player is invalid
        S-->>MT: throw Exception("Player does not meet role requirements")
    end

    MT->>D: bind(Destination)
    D->>Destination: validatePlayer(Destination)
    alt Player is valid
        D-->>MT: Player bound successfully
    else Player is invalid
        D-->>MT: throw Exception("Player does not meet role requirements")
    end

    MT->>S: withdraw(amount)
    S->>Source: getBalance()
    Source-->>S: balance
    alt Insufficient funds
        S-->>MT: throw Exception("Insufficient funds")
    else Sufficient funds
        S->>Source: setBalance(newBalance)
        S-->>MT: Withdrawal successful
    end

    MT->>D: deposit(amount)
    D->>Destination: getBalance()
    Destination-->>D: currentBalance
    D->>Destination: setBalance(newBalance)
    D-->>MT: Deposit successful

    MT->>S: unbind()
    MT->>D: unbind()
  1. First, let's create the Data part (domain objects):
// /src/Model/Entity/Account.php
namespace App\Model\Entity;

use Cake\ORM\Entity;

class Account extends Entity
{
    protected $_accessible = [
        'balance' => true,
        'name' => true
    ];

    protected float $balance;

    public function getBalance(): float
    {
        return $this->get('balance');
    }

    public function setBalance(float $amount): void
    {
        $this->set('balance', $amount);
    }
}
  1. Create Role management classes:
// /src/Context/Contracts/RoleInterface.php
namespace App\Context\Contracts;

interface RoleInterface
{
    public function bind($player): void;
    public function unbind(): void;
    public function getPlayer();
}
// /src/Context/Roles/AbstractRole.php
namespace App\Context\Roles;

use App\Context\Contracts\RoleInterface;

abstract class AbstractRole implements RoleInterface
{
    protected $player;

    public function bind($player): void
    {
        if (!$this->validatePlayer($player)) {
            throw new \InvalidArgumentException('Player does not meet role requirements');
        }
        $this->player = $player;
    }

    public function unbind(): void
    {
        $this->player = null;
    }

    public function getPlayer()
    {
        return $this->player;
    }

    abstract protected function validatePlayer($player): bool;
}
  1. Create roles that define transfer behaviors:
// /src/Context/Roles/MoneySource.php
namespace App\Context\Roles;

use App\Model\Entity\Account;

class MoneySource extends AbstractRole
{
    protected function validatePlayer($player): bool
    {
        return $player instanceof Account
            && method_exists($player, 'getBalance')
            && method_exists($player, 'setBalance');
    }

    public function withdraw(float $amount): void
    {
        $balance = $this->player->getBalance();
        if ($balance < $amount) {
            throw new \Exception('Insufficient funds');
        }
        $this->player->setBalance($balance - $amount);
    }
}
// /src/Context/Roles/MoneyDestination.php
namespace App\Context\Roles;

use App\Model\Entity\Account;

class MoneyDestination extends AbstractRole
{
    protected function validatePlayer($player): bool
    {
        return $player instanceof Account
            && method_exists($player, 'getBalance')
            && method_exists($player, 'setBalance');
    }

    public function deposit(float $amount): void
    {
        $currentBalance = $this->player->getBalance();
        $this->player->setBalance($currentBalance + $amount);
    }
}
  1. Create the context that orchestrates the transfer:
// /src/Context/MoneyTransfer.php

namespace App\Context;

use App\Model\Entity\Account;
use App\Context\Roles\MoneySource;
use App\Context\Roles\MoneyDestination;

class MoneyTransfer
{
    private MoneySource $sourceRole;
    private MoneyDestination $destinationRole;
    private float $amount;

    public function __construct(Account $source, Account $destination, float $amount)
    {
        $this->sourceRole = new MoneySource();
        $this->sourceRole->bind($source);

        $this->destinationRole = new MoneyDestination();
        $this->destinationRole->bind($destination);

        $this->amount = $amount;
    }

    public function execute(): void
    {
        try {
            $this->sourceRole->withdraw($this->amount);
            $this->destinationRole->deposit($this->amount);
        } finally {
            $this->sourceRole->unbind();
            $this->destinationRole->unbind();
        }
    }

    public function __destruct()
    {
        $this->sourceRole->unbind();
        $this->destinationRole->unbind();
    }
}
  1. Implements controller logic
// /src/Controller/AccountsController.php

namespace App\Controller;

use App\Context\MoneyTransfer;

class AccountsController extends AppController
{

    public $Accounts;

    public function initialize(): void
    {
        parent::initialize();
        $this->Accounts = $this->fetchTable('Accounts');

    }

    public function transfer()
    {
        if ($this->request->is(['post'])) {
            $sourceAccount = $this->Accounts->get($this->request->getData('source_id'));
            $destinationAccount = $this->Accounts->get($this->request->getData('destination_id'));
            $amount = (float)$this->request->getData('amount');
            try {
                $context = new MoneyTransfer($sourceAccount, $destinationAccount, $amount);
                $context->execute();

                $this->Accounts->saveMany([
                    $sourceAccount,
                    $destinationAccount
                ]);

                $this->Flash->success('Transfer completed successfully');
            } catch (\Exception $e) {
                $this->Flash->error($e->getMessage());
            }
            return $this->redirect(['action' => 'transfer']);
        }

        $this->set('accounts', $this->Accounts->find('list', valueField: ['name'])->all());
    }
}

Synthesizing DCI Pattern with CakePHP's Architectural Philosophy

One can look at the roles like a behaviors for table records. We can't use table behaviors directly, because it completely breaks the conception of methods separation based on the roles. In case of table behaviors we can't define methods for different roles for same instance as all class objects will have access to all roles methods.

So we're going to implement the behaviors like roles on the entity level.

  1. RoleBehavior layer that mimics CakePHP's behavior system but for entities:
classDiagram
    class RoleBehavior {
        #EntityInterface _entity
        #array _config
        #array _defaultConfig
        +__construct(entity: EntityInterface, config: array)
        +initialize(config: array): void
        +getConfig(key: string|null, default: mixed): mixed
        hasProperty(property: string): bool
        getProperty(property: string): mixed
        setProperty(property: string, value: mixed): void
        +implementedMethods(): array
        +implementedEvents(): array
    }

    class ObjectRegistry {
        #_resolveClassName(class: string): string
        #_create(class: string, alias: string, config: array): object
        #_resolveKey(name: string): string
        +clear(): void
    }

    class RoleRegistry {
        -EntityInterface _entity
        +__construct(entity: EntityInterface)
        #_resolveClassName(class: string): string
        #_create(class: string, alias: string, config: array): RoleBehavior
        #_resolveKey(name: string): string
        +clear(): void
        #_throwMissingClassError(class: string, plugin: string|null): void
    }

    class RoleAwareEntity {
        -RoleRegistry|null _roles
        -array _roleMethods
        #_getRoleRegistry(): RoleRegistry
        +addRole(role: string, config: array): void
        +removeRole(role: string): void
        +hasRole(role: string): bool
        #getRole(role: string): RoleBehavior
        +__call(method: string, arguments: array)
        +hasMethod(method: string): bool
    }

    ObjectRegistry <|-- RoleRegistry
    RoleAwareEntity o-- RoleRegistry
    RoleRegistry o-- RoleBehavior
    RoleAwareEntity ..> RoleBehavior

// /src/Model/Role/RoleBehavior.php
namespace App\Model\Role;

use Cake\Datasource\EntityInterface;
use Cake\Event\EventDispatcherInterface;
use Cake\Event\EventDispatcherTrait;

abstract class RoleBehavior implements EventDispatcherInterface
{
    use EventDispatcherTrait;

    protected EntityInterface $_entity;
    protected array $_config;

    protected $_defaultConfig = [];

    public function __construct(EntityInterface $entity, array $config = [])
    {
        $this->_entity = $entity;
        $this->_config = array_merge($this->_defaultConfig, $config);
        $this->initialize($config);
    }

    /**
     * Initialize hook - like CakePHP behaviors
     */
    public function initialize(array $config): void
    {
    }

    /**
     * Get behavior config
     */
    public function getConfig(?string $key = null, $default = null): mixed
    {
        if ($key === null) {
            return $this->_config;
        }
        return $this->_config[$key] ?? $default;
    }

    /**
     * Check if entity has specific property/method
     */
    protected function hasProperty(string $property): bool
    {
        return $this->_entity->has($property);
    }

    /**
     * Get entity property
     */
    protected function getProperty(string $property): mixed
    {
        return $this->_entity->get($property);
    }

    /**
     * Set entity property
     */
    protected function setProperty(string $property, mixed $value): void
    {
        $this->_entity->set($property, $value);
    }

    /**
     * Get implemented methods - similar to CakePHP behaviors
     */
    public function implementedMethods(): array
    {
        return [];
    }

    /**
     * Get implemented events
     */
    public function implementedEvents(): array
    {
        return [];
    }
}
  1. Now we can create a RoleRegistry to manage roles for entities:
// /src/Model/Role/RoleRegistry.php
namespace App\Model\Role;

use Cake\Core\ObjectRegistry;
use Cake\Datasource\EntityInterface;
use InvalidArgumentException;

class RoleRegistry extends ObjectRegistry
{
    private EntityInterface $_entity;

    public function __construct(EntityInterface $entity)
    {
        $this->_entity = $entity;
    }

    /**
     * Should return a string identifier for the object being loaded.
     *
     * @param string $class The class name to register.
     * @return string
     */
    protected function _resolveClassName(string $class): string
    {
        if (class_exists($class)) {
            return $class;
        }

        $className = 'App\\Model\\Role\\' . $class . 'Role';
        if (!class_exists($className)) {
            throw new InvalidArgumentException("Role class for '{$class}' not found");
        }

        return $className;
    }

    /**
     * Create an instance of a role.
     *
     * @param string $class The class to create.
     * @param string $alias The alias of the role.
     * @param array $config The config array for the role.
     * @return \App\Model\Role\RoleBehavior
     */
    protected function _create($class, string $alias, array $config): RoleBehavior
    {
        return new $class($this->_entity, $config);
    }

    /**
     * Get the key used to store roles in the registry.
     *
     * @param string $name The role name to get a key for.
     * @return string
     */
    protected function _resolveKey(string $name): string
    {
        return strtolower($name);
    }

    /**
     * Clear all roles from the registry.
     *
     * @return void
     */
    public function clear(): void
    {
        $this->reset();
    }

    /**
     * @inheritDoc
     */
    protected function _throwMissingClassError(string $class, ?string $plugin): void
    {
        throw new InvalidArgumentException("Role class for '{$class}' not found");
    }
}
  1. And add role support to Entity:
// /src/Model/Entity/RoleAwareEntity.php
namespace App\Model\Entity;

use App\Model\Role\RoleBehavior;
use App\Model\Role\RoleRegistry;
use Cake\ORM\Entity;
use BadMethodCallException;

class RoleAwareEntity extends Entity
{
    private ?RoleRegistry $_roles = null;
    private array $_roleMethods = [];

    protected function _getRoleRegistry(): RoleRegistry
    {
        if ($this->_roles === null) {
            $this->_roles = new RoleRegistry($this);
        }
        return $this->_roles;
    }

    public function addRole(string $role, array $config = []): void
    {
        $roleInstance = $this->_getRoleRegistry()->load($role, $config);

        foreach ($roleInstance->implementedMethods() as $method => $callable) {
            $this->_roleMethods[$method] = $role;
        }
    }

    public function removeRole(string $role): void
    {
        $this->_roleMethods = array_filter(
            $this->_roleMethods,
            fn($roleType) => $roleType !== $role
        );

        $this->_getRoleRegistry()->unload($role);
    }

    public function hasRole(string $role): bool
    {
        return $this->_getRoleRegistry()->has($role);
    }

    protected function getRole(string $role): RoleBehavior
    {
        return $this->_getRoleRegistry()->load($role);
    }

    public function __call(string $method, array $arguments)
    {
        if (isset($this->_roleMethods[$method])) {
            $role = $this->getRole($this->_roleMethods[$method]);
            return $role->$method(...$arguments);
        }

        throw new BadMethodCallException(sprintf(
            'Method %s::%s does not exist',
            static::class,
            $method
        ));
    }

    public function hasMethod(string $method): bool
    {
        return isset($this->_roleMethods[$method]);
    }
}

  1. Now our Account entity can use roles:

    // /src/Model/Entity/ComplexAccount.php
namespace App\Model\Entity;

/**
 * @method void withdraw(float $amount)
 * @method bool canWithdraw(float $amount)
 * @method void deposit(float $amount)
 * @method bool canDeposit(float $amount)
 * @method void logOperation(string $operation, array $data)
 * @method void notify(string $type, array $data)
 */
class ComplexAccount extends RoleAwareEntity
{
    protected array $_accessible = [
        'balance' => true,
        'account_type' => true,
        'status' => true,
        'is_frozen' => true,
        'created' => true,
        'modified' => true
    ];
}

  2. Let's rewrite the money transfer example using our new role layer system:

classDiagram
    class AuditableBehavior {
        #Table _auditLogsTable
        +initialize(config: array): void
        +logOperation(table: Table, foreignKey: int, operation: string, data: array)
    }

    class RoleBehavior {
        #EntityInterface _entity
        #array _config
        #array _defaultConfig
        +initialize(config: array)
        +getConfig(key: string|null): mixed
        #hasProperty(property: string): bool
        #getProperty(property: string): mixed
        #setProperty(property: string, value: mixed)
    }

    class AuditableRole {
        +implementedMethods(): array
        +logOperation(operation: string, data: array): void
    }

    class TransferSourceRole {
        #ComplexAccount _entity
        #_defaultConfig: array
        +implementedMethods(): array
        +withdraw(amount: float): void
        +canWithdraw(amount: float): bool
    }

    class TransferDestinationRole {
        #ComplexAccount _entity
        #_defaultConfig: array
        +implementedMethods(): array
        +deposit(amount: float): void
        +canDeposit(amount: float): bool
    }

    class MoneyTransferContext {
        -ComplexAccount source
        -ComplexAccount destination
        -float amount
        -ComplexAccountsTable ComplexAccounts
        +__construct(ComplexAccountsTable, source, destination, amount, config)
        -attachRoles(config: array): void
        +execute(): void
        -detachRoles(): void
    }

    class ComplexAccountsController {
        +ComplexAccounts
        +initialize(): void
        +transfer()
    }

    RoleBehavior <|-- AuditableRole
    RoleBehavior <|-- TransferSourceRole
    RoleBehavior <|-- TransferDestinationRole

    MoneyTransferContext --> TransferSourceRole : uses
    MoneyTransferContext --> TransferDestinationRole : uses
    MoneyTransferContext --> AuditableRole : uses
    ComplexAccountsController --> MoneyTransferContext : creates
    AuditableRole ..> AuditableBehavior : uses

    note for TransferSourceRole "Handles withdrawal operations\nand balance validation"
    note for TransferDestinationRole "Handles deposit operations\nand deposit limits"
    note for AuditableRole "Provides audit logging\ncapabilities"
    note for MoneyTransferContext "Orchestrates money transfer\nwith role management"

TransferSourceRole

// /src/Model/Role/TransferSourceRole.php
namespace App\Model\Role;

use App\Model\Entity\ComplexAccount;
use Cake\Datasource\EntityInterface;

class TransferSourceRole extends RoleBehavior
{

    /**
     * @var ComplexAccount
     */
    protected EntityInterface $_entity;

    protected $_defaultConfig = [
        'field' => 'balance',
        'minimumBalance' => 0
    ];

    public function implementedMethods(): array
    {
        return [
            'withdraw' => 'withdraw',
            'canWithdraw' => 'canWithdraw'
        ];
    }

    public function withdraw(float $amount): void
    {
        if (!$this->canWithdraw($amount)) {
            throw new \InvalidArgumentException('Cannot withdraw: insufficient funds or invalid amount');
        }

        $balanceField = $this->getConfig('field');
        $currentBalance = $this->getProperty($balanceField);

        $this->_entity->logOperation('pre_withdrawal', [
            'amount' => $amount,
            'current_balance' => $currentBalance
        ]);

        $this->setProperty($balanceField, $currentBalance - $amount);

        $this->_entity->logOperation('post_withdrawal', [
            'amount' => $amount,
            'new_balance' => $this->getProperty($balanceField)
        ]);
    }

    public function canWithdraw(float $amount): bool
    {
        if ($amount <= 0) {
            return false;
        }

        $balanceField = $this->getConfig('field');
        $minimumBalance = $this->getConfig('minimumBalance');

        return $this->getProperty($balanceField) - $amount >= $minimumBalance &&
               $this->getProperty('status') === 'active' &&
               !$this->getProperty('is_frozen');
    }
}

TransferDestinationRole

// /src/Model/Role/TransferDestinationRole.php
namespace App\Model\Role;

use Cake\Datasource\EntityInterface;

class TransferDestinationRole extends RoleBehavior
{
    /**
     * @var ComplexAccount
     */
    protected EntityInterface $_entity;

    protected $_defaultConfig = [
        'field' => 'balance',
        'maxDeposit' => null
    ];

    public function implementedMethods(): array
    {
        return [
            'deposit' => 'deposit',
            'canDeposit' => 'canDeposit'
        ];
    }

    public function deposit(float $amount): void
    {
        if (!$this->canDeposit($amount)) {
            throw new \InvalidArgumentException('Cannot deposit: invalid amount or limit exceeded');
        }

        $balanceField = $this->getConfig('field');
        $currentBalance = $this->getProperty($balanceField);

        $this->_entity->logOperation('pre_deposit', [
            'amount' => $amount,
            'current_balance' => $currentBalance
        ]);

        $this->setProperty($balanceField, $currentBalance + $amount);

        $this->_entity->logOperation('post_deposit', [
            'amount' => $amount,
            'new_balance' => $this->getProperty($balanceField)
        ]);
    }

    public function canDeposit(float $amount): bool
    {
        if ($amount <= 0) {
            return false;
        }

        $maxDeposit = $this->getConfig('maxDeposit');
        return ($maxDeposit === null || $amount <= $maxDeposit) &&
               $this->getProperty('status') === 'active' &&
               !$this->getProperty('is_frozen');
    }
}
  1. Lets implement audit functionality to show more complex role usage.

AuditableRole

// /src/Model/Role/AuditableRole.php
namespace App\Model\Role;

use Cake\ORM\TableRegistry;

class AuditableRole extends RoleBehavior
{
    public function implementedMethods(): array
    {
        return [
            'logOperation' => 'logOperation'
        ];
    }

    public function logOperation(string $operation, array $data): void
    {
        $table = TableRegistry::getTableLocator()->get($this->_entity->getSource());
        $table->logOperation($table, $this->_entity->id, $operation, $data);
    }
}

AuditableBehavior

// /src/Model/Behavior/AuditableBehavior.php
namespace App\Model\Behavior;

use Cake\ORM\Behavior;
use Cake\ORM\Table;
use Cake\ORM\TableRegistry;

class AuditableBehavior extends Behavior
{
    protected array $_defaultConfig = [
        'implementedMethods' => [
            'logOperation' => 'logOperation',
        ],
    ];

    protected Table $_auditLogsTable;

    public function initialize(array $config): void
    {
        parent::initialize($config);
        $this->_auditLogsTable = TableRegistry::getTableLocator()->get('AuditLogs');
    }

    public function logOperation(Table $table, int $foreignKey, string $operation, array $data = [])
    {
        $log = $this->_auditLogsTable->newEntity([
            'model' => $table->getAlias(),
            'foreign_key' => $foreignKey,
            'operation' => $operation,
            'data' => json_encode($data),
            'created' => new \DateTime()
        ]);

        return $this->_auditLogsTable->save($log);
    }
}
  1. Lets take a look on improved context implementation.
// /src/Context/MoneyTransfer/MoneyTransferContext.php
namespace App\Context\MoneyTransfer;

use App\Model\Entity\ComplexAccount;
use App\Model\Table\ComplexAccountsTable;

class MoneyTransferContext
{
    private readonly ComplexAccount $source;
    private readonly ComplexAccount $destination;
    private readonly float $amount;
    private readonly ComplexAccountsTable $ComplexAccounts;

    public function __construct(
        ComplexAccountsTable $ComplexAccounts,
        ComplexAccount $source,
        ComplexAccount $destination,
        float $amount,
        array $config = []
    ) {
        $this->source = $source;
        $this->destination = $destination;
        $this->amount = $amount;
        $this->ComplexAccounts = $ComplexAccounts;
        $this->attachRoles($config);
    }

    private function attachRoles(array $config): void
    {
        $this->source->addRole('Auditable');
        $this->source->addRole('TransferSource', $config['source'] ?? []);

        $this->destination->addRole('Auditable');
        $this->destination->addRole('TransferDestination', $config['destination'] ?? []);
    }

    public function execute(): void
    {
        try {
            $this->ComplexAccounts->getConnection()->transactional(function() {
                if (!$this->source->canWithdraw($this->amount)) {
                    throw new \InvalidArgumentException('Source cannot withdraw this amount');
                }

                if (!$this->destination->canDeposit($this->amount)) {
                    throw new \InvalidArgumentException('Destination cannot accept this deposit');
                }

                $this->source->withdraw($this->amount);
                $this->destination->deposit($this->amount);

                // This code will not able to work! Methods not attached not available, and logic errors does not possible to perform in context.
                // $this->source->deposit($this->amount);
                // $this->destination->withdraw($this->amount);

                $this->ComplexAccounts->saveMany([
                    $this->source,
                    $this->destination
                ]);
            });
        } finally {
            $this->detachRoles();
        }
    }

    private function detachRoles(): void
    {
        $this->source->removeRole('TransferSource');
        $this->source->removeRole('Auditable');

        $this->destination->removeRole('TransferDestination');
        $this->destination->removeRole('Auditable');
    }
}
  1. And finally lets implements controller logic.
// /src/Controller/ComplexAccountsController.php
namespace App\Controller;

use App\Context\MoneyTransfer\MoneyTransferContext as MoneyTransfer;

class ComplexAccountsController extends AppController
{

    public $ComplexAccounts;

    public function initialize(): void
    {
        parent::initialize();
        $this->ComplexAccounts = $this->fetchTable('ComplexAccounts');

    }

    public function transfer()
    {
        if ($this->request->is(['post'])) {
            try {
                $source = $this->ComplexAccounts->get($this->request->getData('source_id'));
                $destination = $this->ComplexAccounts->get($this->request->getData('destination_id'));
                $amount = (float)$this->request->getData('amount');

                $transfer = new MoneyTransfer($this->ComplexAccounts, $source, $destination, $amount);

                $transfer->execute();

                $this->Flash->success('Transfer completed successfully');

            } catch (\InvalidArgumentException $e) {
                $this->Flash->error($e->getMessage());
            }
            $this->redirect(['action' => 'transfer']);
        }

        $this->set('complexAccounts', $this->ComplexAccounts->find('list', valueField: ['account_type', 'id'])->all());
    }
}

The money transfer flow is shown in the following diagram:

sequenceDiagram
    participant CC as ComplexAccountsController
    participant MT as MoneyTransferContext
    participant SA as Source Account
    participant DA as Destination Account
    participant TSR as TransferSourceRole
    participant TDR as TransferDestinationRole
    participant AR as AuditableRole
    participant AB as AuditableBehavior
    participant DB as Database

    CC->>MT: new MoneyTransfer(accounts, source, destination, amount)
    activate MT

    MT->>SA: addRole('Auditable')
    MT->>SA: addRole('TransferSource')
    MT->>DA: addRole('Auditable')
    MT->>DA: addRole('TransferDestination')

    CC->>MT: execute()

    MT->>SA: canWithdraw(amount)
    SA->>TSR: canWithdraw(amount)
    TSR->>SA: getProperty('balance')
    TSR->>SA: getProperty('status')
    TSR->>SA: getProperty('is_frozen')
    TSR-->>MT: true/false

    alt Can Withdraw
        MT->>DA: canDeposit(amount)
        DA->>TDR: canDeposit(amount)
        TDR->>DA: getProperty('balance')
        TDR->>DA: getProperty('status')
        TDR->>DA: getProperty('is_frozen')
        TDR-->>MT: true/false

        alt Can Deposit
            MT->>SA: withdraw(amount)
            SA->>TSR: withdraw(amount)
            TSR->>SA: logOperation('pre_withdrawal')
            SA->>AR: logOperation('pre_withdrawal')
            AR->>AB: logOperation(table, id, operation, data)
            AB->>DB: save audit log

            TSR->>SA: setProperty(balance, newBalance)

            TSR->>SA: logOperation('post_withdrawal')
            SA->>AR: logOperation('post_withdrawal')
            AR->>AB: logOperation(table, id, operation, data)
            AB->>DB: save audit log

            MT->>DA: deposit(amount)
            DA->>TDR: deposit(amount)
            TDR->>DA: logOperation('pre_deposit')
            DA->>AR: logOperation('pre_deposit')
            AR->>AB: logOperation(table, id, operation, data)
            AB->>DB: save audit log

            TDR->>DA: setProperty(balance, newBalance)

            TDR->>DA: logOperation('post_deposit')
            DA->>AR: logOperation('post_deposit')
            AR->>AB: logOperation(table, id, operation, data)
            AB->>DB: save audit log

            MT->>DB: saveMany([source, destination])
        else Cannot Deposit
            MT-->>CC: throw InvalidArgumentException
        end
    else Cannot Withdraw
        MT-->>CC: throw InvalidArgumentException
    end

    MT->>SA: removeRole('TransferSource')
    MT->>SA: removeRole('Auditable')
    MT->>DA: removeRole('TransferDestination')
    MT->>DA: removeRole('Auditable')
    deactivate MT

    alt Success
        CC->>CC: Flash.success('Transfer completed')
    else Error
        CC->>CC: Flash.error(error.message)
    end

    CC->>CC: redirect(['action' => 'transfer'])

Conclusion

DCI pattern helps us write safer code by controlling what objects can do at any given time. Like in our money transfer example, we make sure the source account can only take money out and the destination account can only receive money. This prevents mistakes and makes the code more secure.

Context is a great way to keep code organized and focused. It serves as an excellent implementation of the Single Responsibility Principle. Each context, like our MoneyTransferContext, does just one thing and does it well. This makes the code easier to understand and test because each piece has a clear job to do.

Even though PHP isn't as flexible as some other programming languages (for example, we can't change object behavior on the fly), we found good ways to make DCI work. Our RoleBehavior and RoleRegistry classes give us a solid way to manage different roles for our objects. CakePHP turns out to be a great framework for using the DCI pattern. We were able to build on CakePHP's existing features, like its behavior system, to create our role-based approach.

Demo Project for Article

The examples used in this article are located at https://github.com/skie/cakephp-dci and available for testing.

This article is part of the CakeDC Advent Calendar 2024 (December 15th 2024)

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The Generational Perception of Work and Productivity in the Remote-Work Era

Generational Work Illustration

The Generational Perception of Work and Productivity in the Remote-Work Era

In the year 2020, everything changed when the world stopped completely during COVID-19. The perception of safety, health, mental health, work, and private life completely turned around and led to a different conception of the world we knew. As the global pandemic thrived, we saw how many jobs could be done from home, because people had to reinvent themselves as we were not able to go to our workplaces. And it settled a statement, changing the perception of work dramatically. Before it, and for older generations, work was associated with physical presence, rigid schedules, and productivity measured by visible hours. But after it, younger generations saw the potential of working from home or being a so-called digital nomad, giving more priority to flexibility, emotional well-being, and measuring efficiency through results. This change reflects a social evolution guided by new technologies, new expectations, and a more connected workforce. Remote work has been key in this transformation. For thousands of professionals, the ability to work from home meant reclaiming personal time, reducing stress, and achieving a healthier work--life balance (for example, by reducing commuting time most people get almost 2 extra hours of personal time). Productivity did not decrease --- in many cases, it actually improved --- because the focus shifted from "time spent" to "goals achieved." This model has also shown that trust and autonomy can lead to more engaged teams. However, despite all of the perks, many companies are apparently eager to return to traditional workplaces. Maybe it is the fear of losing control or a lack of understanding of the new work dynamics, but this tendency threatens to undo meaningful progress for generations that have already experienced the freedom and effectiveness of remote work. Going back to the old-fashioned way of work feels like a step backward. So now, the challenge is to find a middle ground that acknowledges the cultural and technological changes of our time, passing the torch to a new generation of workers. Because productivity is no longer measured by how many people are sitting in a chair, but by the value of the final results. And if we want organizations truly prepared for the future, we must listen to younger generations and build work models that prioritize both results and workers' well-being. In CakeDC we do believe in remote work! Proving through the years that work can be done remotely no matter the timezone or language.

Written by Rcardoso on December 10, 2025

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Scaling Task Processing in CakePHP: Achieving Concurrency with Multiple...

This article is part of the CakeDC Advent Calendar 2025 (December 9th 2025)

Introduction: need of Concurrency

While offloading long-running tasks to an asynchronous queue solves the initial web request bottleneck, relying on a single queue worker introduces a new, serious point of failure and bottleneck. This single-threaded approach transfers the issue from the web server to the queue system itself.

Bottlenecks of Single-Worker Queue Processing

The fundamental limitation in the standard web request lifecycle is its synchronous, single-threaded architecture. This design mandates that a user's request must wait for all associated processing to fully complete before a response can be returned. The Problem: Single-Lane Processing Imagine a queue worker as a single cashier at a very busy bank . Each item in the queue (the "job") represents a customer.
  1. Job Blocking (The Long Transaction): If the single cashier encounters a customer with an extremely long or slow transaction (e.g., generating a massive report, bulk sending 100,000 emails, or waiting for a slow API), every other customer must wait for that transaction to complete.
  2. Queue Backlog Accumulation: New incoming jobs (customers) pile up rapidly in the queue. This is known as a queue backlog. The time between a job being put on the queue and it starting to execute (Job Latency) skyrockets.
  3. Real-Time Failure: If a job requires an action to happen now (like sending a password reset email), the backlog means that action is critically delayed, potentially breaking the user experience or application logic.
  4. Worker Vulnerability and Downtime: If this single worker crashes (due to a memory limit or unhandled error) or is temporarily taken offline for maintenance, queue processing stops entirely. The application suddenly loses its entire asynchronous capability until the worker is manually restarted, resulting in a complete system freeze of all background operations.
To eliminate this bottleneck, queue consumption must be handled by multiple concurrent workers, allowing the system to process many jobs simultaneously and ensuring no single slow job can paralyze the entire queue.

Improved System Throughput and Reliability with Multiple Workers

While introducing a queue solves the initial issue of synchronous blocking, scaling the queue consumption with multiple concurrent workers is what unlocks significant performance gains and reliability for the application's background processes.

Key Benefits of Multi-Worker Queue Consumption

  • Consistent, Low Latency: Multiple workers process jobs in parallel, preventing any single slow or heavy job (e.g., report generation) from causing a queue backlog. This ensures time-sensitive tasks, like password resets, are processed quickly, maintaining instant user feedback.
  • Enhanced Reliability and Resilience: If one worker crashes, the other workers instantly take over** the remaining jobs. This prevents a complete system freeze and ensures queue processing remains continuous.
  • Decoupling and Effortless Scaling: The queue facilitates decoupling. When background load increases, you simply deploy more CakePHP queue workers. This horizontal scaling is simple, cost-effective, and far more efficient than scaling the entire web server layer.

Workflows that Benefit from Multi-Worker Concurrency

These examples show why using multiple concurrent workers with the CakePHP Queue plugin (https://github.com/cakephp/queue) is essential for performance and reliability:
  • Mass Email Campaigns (Throughput): Workers process thousands of emails simultaneously, drastically cutting the time for large campaigns and ensuring the entire list is delivered fast.
  • Large Media Processing (Parallelism): Multiple workers handle concurrent user uploads or divide up thumbnail generation tasks. This speeds up content delivery by preventing one heavy image from blocking all others.
  • High-Volume API Synchronization (Consistency): Workers ensure that unpredictable external API latency from one service doesn't paralyze updates to another. This maintains a consistent, uninterrupted flow of data across all integrations.

The Job

Lets say that you have the queue job like this: <?php declare(strict_types=1); namespace App\Job; use Cake\Mailer\Mailer; use Cake\ORM\TableRegistry; use Cake\Queue\Job\JobInterface; use Cake\Queue\Job\Message; use Interop\Queue\Processor; /** * SendBatchNotification job */ class SendBatchNotificationJob implements JobInterface { /** * The maximum number of times the job may be attempted. * * @var int|null */ public static $maxAttempts = 10; /** * We need to set the shouldBeUnique to true to avoid race condition with multiple queue workers * * @var bool */ public static $shouldBeUnique = true; /** * Executes logic for SendBatchNotificationJob * * @param \Cake\Queue\Job\Message $message job message * @return string|null */ public function execute(Message $message): ?string { // 1. Retrieve job data from the message object $data = $message->getArgument('data'); $userId = $data['user_id'] ?? null; if (!$userId) { // Log error or skip, but return ACK to remove from queue return Processor::ACK; } try { // 2. Load user and prepare email $usersTable = TableRegistry::getTableLocator()->get('Users'); $user = $usersTable->get($userId); $mailer = new Mailer('default'); $mailer ->setTo($user->email) ->setSubject('Your batch update is complete!') ->setBodyString("Hello {$user->username}, \n\nThe recent batch process for your account has finished."); // 3. Send the email (I/O operation that can benefit from concurrency) $mailer->send(); } catch (\Exception $e) { // If the email server fails, we can tell the worker to try again later // The queue system will handle the delay and retry count. return Processor::REQUEUE; } // Success: Acknowledge the job to remove it from the queue return Processor::ACK; } } Setting $shouldBeUnique = true; in a CakePHP Queue Job class is crucial for preventing a race condition when multiple queue workers consume the same queue, as it ensures only one instance of the job is processed at any given time, thus avoiding duplicate execution or conflicting updates. In another part of the application you have code that enqueues the job like this: // In a Controller, Command, or Service Layer: use Cake\ORM\TableRegistry; use Cake\Queue\QueueManager; use App\Job\SendBatchNotificationJob; // Our new Job class // Find all users who need notification (e.g., 500 users) $usersToNotify = TableRegistry::getTableLocator()->get('Users')->find()->where(['is_notified' => false]); foreach ($usersToNotify as $user) { // Each loop iteration dispatches a distinct, lightweight job $data = [ 'user_id' => $user->id, ]; // Dispatch the job using the JobInterface class name QueueManager::push(SendBatchNotificationJob::class, $data); } // Result: 500 jobs are ready in the queue. By pushing 500 separate jobs, you allow 10, 20, or even 50 concurrent workers to pick up these small jobs and run the email sending logic in parallel, drastically reducing the total time it takes for all 500 users to receive their notification.

Implementing Concurrency with multiple queue workers

In modern Linux distributions, systemd is the preferred init and service manager. By leveraging User Sessions and the Lingering feature, we can run the CakePHP worker as a dedicated, managed service without needing root privileges for the process itself, offering excellent stability and integration.

SystemD User Sessions

Prerequisite: The Lingering User Session

For a service to run continuously in the background, even after the user logs out, we must enable the lingering feature for the user account that will run the workers (e.g., a service user named appuser). Enabling Lingering: Bash sudo loginctl enable-linger appuser This ensures the appuser's systemd user session remains active indefinitely, allowing the worker processes to survive server reboots and user logouts.

Creating the Systemd User Unit File

We define the worker service using a unit file, placed in the user's systemd configuration directory (~/.config/systemd/user/).
  • File Location: ~appuser/.config/systemd/user/[email protected]
  • Purpose of @: The @ symbol makes this a template unit. This allows us to use a single file to create multiple, distinct worker processes, which is key to achieving concurrency.
[email protected] Content: Ini, TOML [Unit] Description=CakePHP Queue Worker #%i After=network.target [Service] # We use the full path to the PHP executable ExecStart=/usr/bin/php /path/to/your/app/bin/cake queue worker # Set the current working directory to the application root WorkingDirectory=/path/to/your/app # Restart the worker if it fails (crashes, memory limit exceeded, etc.) Restart=always # Wait a few seconds before attempting a restart RestartSec=5 # Output logs to the systemd journal StandardOutput=journal StandardError=journal # Ensure permissions are correct and process runs as the user User=appuser [Install] WantedBy=default.target

Achieving Concurrency (Scaling the Workers)

Concurrency is achieved by enabling multiple instances of this service template, distinguished by the suffix provided in the instance name (e.g., -1, -2, -3). Reload and Start Instances: After creating the file, the user session must be reloaded, and the worker instances must be started and enabled: Reload Daemon (as appuser): Bash systemctl --user daemon-reload Start and Enable Concurrent Workers (as appuser): To run three workers concurrently: Bash # Start Worker Instance 1 systemctl --user enable --now [email protected] # Start Worker Instance 2 systemctl --user enable --now [email protected] # Start Worker Instance 3 systemctl --user enable --now [email protected] Result: The system now has three independent and managed processes running the bin/cake queue worker command, achieving a concurrent processing pool of three jobs.

Monitoring and Management

systemd provides powerful tools for managing and debugging the worker pool: Check Concurrency Status: Bash systemctl --user status 'cakephp-worker@*' This command displays the status of all concurrent worker instances, showing which are running or if any have failed and been automatically restarted. Viewing Worker Logs: All output is directed to the systemd journal: Bash journalctl --user -u 'cakephp-worker@*' -f This allows developers to inspect errors and task completion messages across all concurrent workers from a single, centralized log. Using systemd and lingering is highly advantageous as it eliminates the need for a third-party tool, integrates naturally with system logging, and provides reliable process management for a robust, concurrent task environment.

Summary

Shifting from a single worker to multiple concurrent workers is essential to prevent bottlenecks and system freezes caused by slow jobs, ensuring high reliability and low latency for asynchronous tasks. One robust way to achieve this concurrency in CakePHP applications is by using Systemd User Sessions and template unit files (e.g., [email protected]) to easily manage and horizontally scale the worker processes. This article is part of the CakeDC Advent Calendar 2025 (December 9th 2025)

Written by Arusinowski on December 08, 2025

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Notifications That Actually Work

This article is part of the CakeDC Advent Calendar 2025 (December 8th 2025) Building a modern application without notifications is like running a restaurant without telling customers their food is ready. Users need to know what's happening. An order shipped. A payment went through. Someone mentioned them in a comment. These moments matter, and how you communicate them matters even more. I've built notification systems before. They always started simple. Send an email when something happens. Easy enough. Then someone wants in-app notifications. Then someone needs Slack alerts. Then the mobile team wants push notifications. Before you know it, you're maintaining five different notification implementations, each with its own bugs and quirks. That's exactly why the CakePHP Notification plugin exists. It brings order to the chaos by giving you one consistent way to send notifications, regardless of where they're going or how they're being delivered. The core notification system (crustum/notification) provides the foundation with database and email support built in.

Two Worlds of Notifications

Notifications naturally fall into two categories, and understanding this split helps you architect your system correctly. The first category is what I call presence notifications. These are for users actively using your application. They're sitting there, browser open, working away. You want to tell them something right now. A new message arrived. Someone approved their request. The background job finished. These notifications need to appear instantly in the UI, update the notification bell, and maybe play a sound. They live in your database and get pushed to the browser through WebSockets. The second category is reach-out notifications. These go find users wherever they are. Email reaches them in their inbox. SMS hits their phone. Slack pings them in their workspace. Telegram messages appear on every device they own. These notifications cross boundaries, reaching into other platforms and services to deliver your message. Understanding this distinction is crucial because these two types of notifications serve different purposes and require different technical approaches. Presence notifications need a database to store history and WebSocket connections for real-time delivery. Reach-out notifications need API integrations and reliable delivery mechanisms.

The Beautiful Part: One Interface

Here's where it gets good. Despite these two worlds being completely different, you write the same code to send both types. Your application doesn't care whether a notification goes to the database, WebSocket, email, or Slack. You just say "notify this user" and the system handles the rest. $user = $this->Users->get($userId); $user->notify(new OrderShipped($order)); That's it. The OrderShipped notification might go to the database for the in-app notification bell, get broadcast via WebSocket for instant delivery, and send an email with tracking information. All from that one line of code.

Web interface for notifications

Let's talk about the in-app notification experience first. This is what most users interact with daily. That little bell icon in the corner of your application. Click it, see your notifications. It's so common now that users expect it. The NotificationUI plugin (crustum/notification-ui) provides a complete notification interface out of the box. There's a bell widget that you drop into your layout, and it just works. It shows the unread count, displays notifications in a clean interface, marks them as read when clicked, and supports actions like buttons in the notification. You have two display modes to choose from. Dropdown mode gives you the traditional experience where clicking the bell opens a menu below it. Panel mode creates a sticky side panel that slides in from the edge of your screen, similar to what you see in modern admin panels. Setting it up takes just a few lines in your layout template. <?= $this->element('Crustum/NotificationUI.notifications/bell_icon', [ 'mode' => 'panel', 'pollInterval' => 30000, ]) ?> The widget automatically polls the server for new notifications every 30 seconds by default. This works perfectly fine for most applications. Users see new notifications within a reasonable time, and your server isn't overwhelmed with requests. But sometimes 30 seconds feels like forever. When someone sends you a direct message, you want to see it immediately. That's where real-time broadcasting comes in.

Real-Time Broadcasting for Instant Delivery

Adding real-time broadcasting transforms the notification experience. Instead of polling every 30 seconds, new notifications appear instantly through WebSocket connections. The moment someone triggers a notification for you, it pops up in your interface. The beautiful thing is you can combine both approaches. Keep database polling as a fallback, add real-time broadcasting for instant delivery. If the WebSocket connection drops, polling keeps working. When the connection comes back, broadcasting takes over again. Users get reliability and instant feedback. <?php $authUser = $this->request->getAttribute('identity'); ?> <?= $this->element('Crustum/NotificationUI.notifications/bell_icon', [ 'mode' => 'panel', 'enablePolling' => true, 'broadcasting' => [ 'userId' => $authUser->getIdentifier(), 'userName' => $authUser->username, 'pusherKey' => 'app-key', 'pusherHost' => '127.0.0.1', 'pusherPort' => 8080, ], ]) ?> This hybrid approach gives you the best of both worlds. Real-time when possible, reliable fallback always available. Behind the scenes, this uses the Broadcasting (crustum/broadcasting) and BroadcastingNotification (crustum/notification-broadcasting) plugins working together. When you broadcast a notification, it goes through the same WebSocket infrastructure. The NotificationUI plugin handles subscribing to the right channels and updating the interface when broadcasts arrive.

Creating Your Notification Classes

Notifications in CakePHP are just classes. Each notification type gets its own class that defines where it goes and what it contains. This keeps everything organized and makes notifications easy to test. namespace App\Notification; use Crustum\Notification\Notification; use Crustum\Notification\Message\DatabaseMessage; use Crustum\Notification\Message\MailMessage; use Crustum\BroadcastingNotification\Message\BroadcastMessage; use Crustum\BroadcastingNotification\Trait\BroadcastableNotificationTrait; class OrderShipped extends Notification { use BroadcastableNotificationTrait; public function __construct( private $order ) {} public function via($notifiable): array { return ['database', 'broadcast', 'mail']; } public function toDatabase($notifiable): DatabaseMessage { return DatabaseMessage::new() ->title('Order Shipped') ->message("Your order #{$this->order->id} has shipped!") ->actionUrl(Router::url(['controller' => 'Orders', 'action' => 'view', $this->order->id], true)) ->icon('check'); } public function toMail($notifiable): MailMessage { return MailMessage::create() ->subject('Your Order Has Shipped') ->greeting("Hello {$notifiable->name}!") ->line("Great news! Your order #{$this->order->id} has shipped.") ->line("Tracking: {$this->order->tracking_number}") ->action('Track Your Order', ['controller' => 'Orders', 'action' => 'track', $this->order->id]); } public function toBroadcast(EntityInterface|AnonymousNotifiable $notifiable): BroadcastMessage|array { return new BroadcastMessage([ 'title' => 'Order Shipped', 'message' => "Your order #{$this->order->id} has shipped!", 'order_id' => $this->order->id, 'order_title' => $this->order->title, 'tracking_number' => $this->order->tracking_number, 'action_url' => Router::url(['controller' => 'Orders', 'action' => 'view', $this->order->id], true), ]); } public function broadcastOn(): array { return [new PrivateChannel('users.' . $notifiable->id)]; } } The via method tells the system which channels to use. The toDatabase method formats the notification for display in your app. The toMail method creates an email. The toBroadcast method formats the notification for broadcast. The broadcastOn method specifies which WebSocket channels to broadcast to. One notification class, three different formats, all sent automatically when you call notify. That's the power of this approach.

Reach-Out Notifications

Now let's talk about reaching users outside your application. This is where the plugin really shines because there are so many channels available. Email is the classic. Everyone has email. The base notification plugin gives you a fluent API for building beautiful transactional emails. You describe what you want to say using simple methods, and it generates a responsive HTML email with a plain text version automatically. Slack integration (crustum/notification-slack) lets you send notifications to team channels. Perfect for internal alerts, deployment notifications, or monitoring events. You get full support for Slack's Block Kit, so you can create rich, interactive messages with buttons, images, and formatted sections. Telegram (crustum/notification-telegram) reaches users on their phones. Since Telegram has a bot API, you can send notifications directly to users who've connected their Telegram account. The messages support formatting, buttons, and even images. SMS through Seven.io (crustum/notification-seven) gets messages to phones as text messages. This is great for critical alerts, verification codes, or appointment reminders. Things that need immediate attention and work even without internet access. RocketChat (crustum/notification-rocketchat) is perfect if you're using RocketChat for team communication. Send notifications to channels or direct messages, complete with attachments and formatting. The plugin system allows you to add new notification channels easily. You can create a new plugin for a new channel and install it like any other plugin. The brilliant part is that adding any of these channels to a notification is just adding a string to the via array and implementing one method. Want to add Slack to that OrderShipped notification? Add 'slack' to the array and implement toSlack. Done. public function via($notifiable): array { return ['database', 'broadcast', 'mail', 'slack']; } public function toSlack($notifiable): BlockKitMessage { return (new BlockKitMessage()) ->text('Order Shipped') ->headerBlock('Order Shipped') ->sectionBlock(function ($block) { $block->text("Order #{$this->order->id} has shipped!"); $block->field("*Customer:*\n{$notifiable->name}"); $block->field("*Tracking:*\n{$this->order->tracking_number}"); }); } Now when someone's order ships, they get an in-app notification with real-time delivery, an email with full details, and your team gets a Slack message in the orders channel. All automatic.

The Database as Your Notification Store

Every notification sent through the database channel gets stored in a notifications table. This gives you a complete history of what users were notified about and when. The NotifiableBehavior adds methods to your tables for working with notifications. $user = $usersTable->get($userId); $unreadNotifications = $usersTable->unreadNotifications($user)->all(); $readNotifications = $usersTable->readNotifications($user)->all(); $usersTable->markNotificationAsRead($user, $notificationId); $usersTable->markAllNotificationsAsRead($user); The UI widget uses these methods to display notifications and mark them as read. But you can use them anywhere in your application. Maybe you want to show recent notifications on a user's dashboard. Maybe you want to delete old notifications. The methods are there.

Queuing for Performance

Sending notifications, especially external ones, takes time. Making API calls to Slack, Seven.io, or Pusher adds latency to your request. If you're sending to multiple channels, that latency multiplies. The solution is queuing. Implement the ShouldQueueInterface on your notification class, and the system automatically queues notification sending as background jobs. use Crustum\Notification\ShouldQueueInterface; class OrderShipped extends Notification implements ShouldQueueInterface { protected ?string $queue = 'notifications'; } Now when you call notify, it returns immediately. The actual notification sending happens in a background worker. Your application stays fast, users don't wait, and notifications still get delivered reliably.

Testing Your Notifications

Testing notification systems used to be painful. You'd either send test notifications to real services (annoying) or mock everything (fragile). The NotificationTrait makes testing clean and simple. use Crustum\Notification\TestSuite\NotificationTrait; class OrderTest extends TestCase { use NotificationTrait; public function testOrderShippedNotification() { $user = $this->Users->get(1); $order = $this->Orders->get(1); $user->notify(new OrderShipped($order)); $this->assertNotificationSentTo($user, OrderShipped::class); $this->assertNotificationSentToChannel('mail', OrderShipped::class); $this->assertNotificationSentToChannel('database', OrderShipped::class); } } The trait captures all notifications instead of sending them. You can assert that the right notifications were sent to the right users through the right channels. You can even inspect the notification data to verify it contains the correct information. There are many diferent assertions you can use to test your notifications. You can assert that the right notifications were sent to the right users through the right channels. You can even inspect the notification data to verify it contains the correct information.

Localization

Applications serve users in different languages, and your notifications should respect that. The notification system integrates with CakePHP's localization system. $user->notify((new OrderShipped($order))->locale('es')); Even better, users can have a preferred locale stored on their entity. Implement a preferredLocale method or property, and notifications automatically use it. class User extends Entity { public function getPreferredLocale(): string { return $this->locale; } } Now you don't even need to specify the locale. The system figures it out automatically and sends notifications in each user's preferred language.

Bringing It Together

What I like about this notification system is how it scales with your needs. Start simple. Just database notifications. Add real-time broadcasting when you want instant delivery. Add email when you need to reach users outside your app. Add Slack when your team wants internal alerts. Add SMS for critical notifications. Each addition is incremental. You're not rewriting your notification system each time. You're adding channels to the via array and implementing format methods. The core logic stays the same. The separation between presence notifications and reach-out notifications makes architectural sense. They serve different purposes, use different infrastructure, but share the same interface. This makes your code clean, your system maintainable, and your notifications reliable. Whether you're building a small application with basic email notifications or a complex system with real-time updates, database history, email, SMS, and team chat integration, you're using the same patterns. The same notification classes. The same notify method. That consistency is what makes the system powerful. You're not context switching between different notification implementations. You're just describing what should be notified, who should receive it, and how it should be formatted. The system handles the rest. This article is part of the CakeDC Advent Calendar 2025 (December 8th 2025)

Written by Yevgeny on December 08, 2025

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