ipc07 talk - beautiful code with aop and di

Beautiful Code with AOP and DIInternational PHP Conference – Frankfurt, Germany

CAUTION!HOT CODE

Overview

Background Information

Domain Driven Design

Components and Dependecy Injection

Aspect Oriented Programming

TYPO3 Framework

Background Information

Mission "Ease of Use"

"Ease of Use" has been identified as the main topic for next TYPO3 versions

First steps were founding the TYPO3 Association, building a brand and "zapping the Gremlins"

Decision to rewrite TYPO3 based on a new architecture to achieve Ease of Use for developers

Currently TYPO3 5.0 is being developed - the 4.x branch will still be improved and see new features

Background Information

Core + Extensions = TYPO3

Background Information

Three Sub-Projects

TYPO3 CMS TYPO3 Framework TYPO3 CR

Background Information

Empty Canvas

?

Background Information

(Some) Guiding Principles

anticipate real world needs

focus on the domain

centralize concerns

convention over configuration

human readable code

modularity everywhere

design decisions can be changed

Background Information

5 Development Methods

Work where it matters (DDD)

Work where it belongs to (DRY)

No chaos, ever (TDD)

No bad surprises (CI)

Innovation built-in (DI, AOP, GUI)

... and more XP techniques

Domain Driven Design

Don't Repeat Yourself

Test Driven Development

ContinuousIntegration Dependency Injection

Aspect Orient ProgrammingGraphical User Interface

Domain Driven Design

A domain is the activity or business of the user

Domain Driven Design is about

focussing on the domain and domain logic

accurately mapping the domain concepts to software

forming a ubiquitous language among the project members

Domain Driven Design

Why focus on the Domain?

Most time in development is spent on infrastructure instead of user interfaces and business logic.

We don't want that.

Domain Driven Design

Ubiquitous language

The common vocabulary is an important prerequisitefor successful collaboration

Use the same words for discussion, modeling, developmentand documentation

Domain Driven Design

Phone Book Domain Model

Domain Driven Design

More phone book actions

show phone book entries

check if user may delete phone book entry

export phone book entries

log phone book actions

Domain Driven Design

More phone book actions

show phone book entries

check if user may delete phone book entry

export phone book entries

log phone book actions✘ not in the domain of a phone book

Domain Driven Design

Layered Architecture

Presentation

Domain

Data source

Application Logic (Service Layer)

Domain Model (Domain Layer)

View

Controller

Data Mapper (part of Content Repository)

Data Source Abstraction

Domain Driven Design

Layered Architecture

Presentation

Domain

Data source

Application Logic (Service Layer)

Domain Model (Domain Layer)

View

Controller

Data Mapper (part of Content Repository)

Data Source Abstraction

Domain Driven Design

Domain-Driven Design

$res = $DB->execQuery('SELECT cnumber FROM customers WHERE lastname LIKE "Sarkosh"'); if (!$res) throw new Exception; $c = mysql_fetch_assoc($res); if (!is_array($c)) throw new Exception; $res = $DB->execQuery('SELECT * FROM registrations WHERE cnumber =' . intval($c['cnumber'])); $reg = mysql_fetch_assoc($res); if (!is_array($reg)) { $this->log('Registration not found'); throw new Exception; } if (!$reg['status'] == 3) throw new Exception;

„Cancel the registration for Mr. Sarkosh“

Domain Driven Design

Domain-Driven Design

„Cancel the registration for Mr. Sarkosh“

$customer = $this->customerRepository->findByLastname('Sarkosh'); $event = $this->eventRepository->getEvent('IPC07');$event->addParticipant($customer);$event->removeParticipant($customer);

$customer = $this->customerRepository->findByLastname('Sarkosh'); $event = $this->eventRepository->getEvent('IPC07'); $registrationService->cancelRegistration($event, $customer);

Components

Components

Playing with building blocks

In TYPO3 5.0, objects considered as components

The combination of components used is configurable(orchestration)

The less components know about each other the easier it is to reuse them in a variety of contexts

Create your own LEGO set by creating cleanly separated, decoupled components!

Components

Component Dependencies

Components seldomly come alone

Components depend on other components which depend on other components which ...

Inspiring people toshare

Components

Component Dependencies

Components seldomly come alone

Components depend on other components which depend on other components which ...

Problem:

Components explicitly refer to other components:$event = new Event();

Inspiring people toshare

Components

Component Dependencies

Possible solutions:

Factory pattern (GoF):$event = EventFactory::createEvent();

Registry pattern (Fowler) / Service Locator:class ServiceLocator { public function registerComponent($name, $component) {} public function getInstance($name);}

Inspiring people toshare

Components

Dependency Injection

A component doesn't ask for the instance of another component but gets it injected

This a type of "Inversion of Control" also referred to as the "Hollywood Principle": "Don't call us, we'll call you"

Enforces loose coupling and high cohesion

Makes you a better programmer

Components

Practical examples for DI

Example using ...

Constructor Injection

Setter Injection

Autowiring Demo

Aspect Oriented Programming

AOP is a programming paradigm

complements OOP by separating concerns to improve modularization

OOP modularizes concerns: methods, classes, packages

AOP addresses cross-cutting concerns

Aspect Oriented Programming

Cross-cutting concerns

Presentation

Domain

Data source

Aspect Oriented Programming

Cross-cutting concerns

Presentation

Domain

Data source

The concerns

live here

Aspect Oriented Programming

Cross-cutting concerns

Event Domain Model

Security

Logging

CONCERNSX-ING

Aspect Oriented Programming

Some Definitions

Advice

encapsulated code, to be re-used

Joinpoint

places in the code where advice can be applied

Pointcut

identifies set of joinpoints where advice should be applied

Aspect

groups advices and pointcuts

Aspect Oriented Programming

Aspects in action

Demo

Read before first use

Try it yourself

Try it yourself

(Advertising)

The TYPO3 Framework is the only PHP-based solution which truly supports Domain Driven Design

powerful, transparent and plain PHP-based AOP support(no extension required, no compile step)

full-featured IoC container with Dependency Injection

great (and big) community, backed by the TYPO3 Association

....

Try it yourself

Installation

You need PHP6

Current installation options:

svn checkout http://5-0.dev.typo3.org/svn/TYPO3/

download the TYPO3 installer

Try it yourself

Installation

When ...?

Recommended literature

Recommended literature

Eric Evans:

Domain Driven DesignTackling Complexity in the Heart of Software

Addison Wesley 2002

Martin Fowler:Patterns of Enterprise Application Architecture

Addison Wesley 2002

Recommended literature

Jimmy Nilsson:Applying Domain-DrivenDesign and Patterns

Addison Wesley 2006

Recommended literature

Links

TYPO3 5.0 Subsitehttp://typo3.org/gimmefive

TYPO3 5.0 Development Websitehttp://5-0.dev.typo3.org

TYPO3 5.0 Documentationhttp://5-0.dev.typo3.org/guide

So long and thanks for the fish

Questionsrobert@typo3.org