“ Aspect-Oriented Web Development in PHP” Jorge Esparteiro Garcia February , 8 th 2008

Agenda Introduction Motivation Aspect Oriented Programming Web Development PHP Web Development Aspect Oriented PHP Development Tools Comparison of the Tools Conclusions Future Work

Introduction

Motivation

Aspect Oriented Programming

Web Development

PHP Web Development

Aspect Oriented PHP Development Tools

Comparison of the Tools

Conclusions

Future Work

Introduction Growing Number of Web applications Web applications more complex Harder to separate Independent concerns Aspect Oriented Programming better separate concerns than previous methodologies Provides Modularization of crosscutting concerns Reduce time and complexity of applications

Growing Number of Web applications

Web applications more complex

Harder to separate Independent concerns

Aspect Oriented Programming better separate concerns than previous methodologies

Provides Modularization of crosscutting concerns

Reduce time and complexity of applications

Motivation AOP can be used with common object oriented language Much of research on developing standalone applications Less applied to Web development. Web development can be improved using aspect-oriented techniques. Developing AOP Web application using PHP – most used programming language. We believe Web development can be improved using AO techniques.

AOP can be used with common object oriented language

Much of research on developing standalone applications

Less applied to Web development.

Web development can be improved using aspect-oriented techniques.

Developing AOP Web application using PHP – most used programming language.

We believe Web development can be improved using AO techniques.

Aspect Oriented Programming (AOP) New technology for separating concerns into single units: Aspects Aspect : Modular unit of crosscutting implementation Encapsulates behaviors that affect multiple classes into reusable modules.

New technology for separating concerns into single units: Aspects

Aspect : Modular unit of crosscutting implementation

Encapsulates behaviors that affect multiple classes into reusable modules.

Aspect Oriented Programming (AOP) AOP weaving process Programming in our native OO language Deal separately with crosscutting concerns by implementing aspects Code and aspects are combined into a final executable using an aspect weaver The original code doesn't need to know about any functionality the aspect has added it only needs to be recompiled without the aspect to regain the original functionality.

AOP weaving process

Programming in our native OO language

Deal separately with crosscutting concerns by implementing aspects

Code and aspects are combined into a final executable using an aspect weaver

The original code doesn't need to know about any functionality the aspect has added

it only needs to be recompiled without the aspect to regain the original functionality.

Aspect Oriented Programming (AOP) Weaving Process

Weaving Process

AOP Web Development Concerns on Web Development Security Authentication Design by Contract Conditions fulfilled before executing a method Some programming languages use the notion of assertion Exception Handling Notification Policy

Concerns on Web Development

Security

Authentication

Design by Contract

Conditions fulfilled before executing a method

Some programming languages use the notion of assertion

Exception Handling

Notification Policy

AOP Web Development Concerns on Web Development (cont.) Logging Logger Behavior – Messages printed out when certain points are reached in the execution of the program Profiling Measures time consumed in some methods. Helpful for detecting bottlenecks. Pooling Strategy to obtain faster database connections. Maintained a pool of connections and resources

Concerns on Web Development (cont.)

Logging

Logger Behavior – Messages printed out when certain points are reached in the execution of the program

Profiling

Measures time consumed in some methods. Helpful for detecting bottlenecks.

Pooling

Strategy to obtain faster database connections. Maintained a pool of connections and resources

AOP Web Development Concerns on Web Development (cont.) Caching Retention of data to minimize network traffic flow and/or disk accesses. Crucial concerns in the development of a web application: Pooling Caching Security

Concerns on Web Development (cont.)

Caching

Retention of data to minimize network traffic flow and/or disk accesses.

Crucial concerns in the development of a web application:

Pooling

Caching

Security

PHP Web Development Most popular server-side scripting systems on the web Loose language – dynamically typed Simplicity Shorter development cycles Easier maintenance Lower training costs Native support for XML and other Web technologies.

Most popular server-side scripting systems on the web

Loose language – dynamically typed

Simplicity

Shorter development cycles

Easier maintenance

Lower training costs

Native support for XML and other Web technologies.

Aspect Oriented PHP development tools We consider two main methods of the extensions to support AOP in PHP Preprocessing weaving A preprocessor is used to perform source code transformations and carry the weaving process. Then the source code is produced Runtime Weaving No previous code generation – The weaving process in done dynamically

We consider two main methods of the extensions to support AOP in PHP

Preprocessing weaving

A preprocessor is used to perform source code transformations and carry the weaving process. Then the source code is produced

Runtime Weaving

No previous code generation – The weaving process in done dynamically

Aspect Oriented PHP development tools Preprocessing weaving method tools (1) PHPAspect Based on Lex and Yacc analysis to generate xml parse trees. XSLT is used to perform the source code transformation on those trees. Contains all the "traditionnals" joinpoints.

Preprocessing weaving method tools (1)

PHPAspect

Based on Lex and Yacc analysis to generate xml parse trees.

XSLT is used to perform the source code transformation on those trees.

Contains all the "traditionnals" joinpoints.

Aspect Oriented PHP development tools PHPAspect Weaving Chain

PHPAspect Weaving Chain

Aspect Oriented PHP development tools Preprocessing weaving method tools (2) Aspect-Oriented PHP(aoPHP) Uses a preprocessor for the PHP programming language written in Java This preprocessor is responsible for the weaving process of the aspects and the base-code. aoPHP contains support to the methods: execution/call, field read and write, among others. Very Simple implementation

Preprocessing weaving method tools (2)

Aspect-Oriented PHP(aoPHP)

Uses a preprocessor for the PHP programming language written in Java

This preprocessor is responsible for the weaving process of the aspects and the base-code.

aoPHP contains support to the methods: execution/call, field read and write, among others.

Very Simple implementation

Aspect Oriented PHP development tools Runtime Weaving (1) aspectPHP Works in application runtime, taking advantage of the interpreted nature of the PHP language. A first version of this tool was adapted from aoPHP implementation Assumed all the aspects are already located in the same directory, as separate files "*.aspect". The aspects are then loaded in sequence by the weaver, to weave them with the original code.

Runtime Weaving (1)

aspectPHP

Works in application runtime, taking advantage of the interpreted nature of the PHP language.

A first version of this tool was adapted from aoPHP implementation

Assumed all the aspects are already located in the same directory, as separate files "*.aspect".

The aspects are then loaded in sequence by the weaver, to weave them with the original code.

Aspect Oriented PHP development tools Runtime Weaving (2) GAP: Generic Aspects for PHP First implementation that supports dynamic weaving, genericity and an extensible pointcut language. Uses the PHP Runkit extension Definition of aspects is obtained through the creation of classes. The creation of pointcuts and association of advice to the joint points is carried through with the aid of annotations - Precedes the class definition.

Runtime Weaving (2)

GAP: Generic Aspects for PHP

First implementation that supports dynamic weaving, genericity and an extensible pointcut language.

Uses the PHP Runkit extension

Definition of aspects is obtained through the creation of classes.

The creation of pointcuts and association of advice to the joint points is carried through with the aid of annotations - Precedes the class definition.

Aspect Oriented PHP development tools The weaving chain of GAP

The weaving chain of GAP

Comparison of the tools Preprocessing weaving tools Advantages Adds the possibility of using AOP paradigm applied on the PHP Web Development Disadvantages Preprocessing adds an extra step to the development of a PHP Web application. Need of extra compilers and preprocessors on the server The generated code won´t run natively on any PHP interpreter Increases Development time

Preprocessing weaving tools

Advantages

Adds the possibility of using AOP paradigm applied on the PHP Web Development

Disadvantages

Preprocessing adds an extra step to the development of a PHP Web application.

Need of extra compilers and preprocessors on the server

The generated code won´t run natively on any PHP interpreter

Increases Development time

Comparison of the tools Runtime weaving tools Advantages No preprocessing – The weaving process in done dynamically No need of extra compilers or preprocessors line preprocessing Apply aspects selectively in runtime Interpretative nature of PHP persists. Disadvantages Slower than preprocessing - Manage runtime aspects Do not implement the new language constructs

Runtime weaving tools

Advantages

No preprocessing – The weaving process in done dynamically

No need of extra compilers or preprocessors line preprocessing

Apply aspects selectively in runtime

Interpretative nature of PHP persists.

Disadvantages

Slower than preprocessing - Manage runtime aspects

Do not implement the new language constructs

Conclusions AOP can modularize crosscutting concerns in Web Applications. Little AOP research on Web development. All AOP PHP tools are on a very early stage of development. GAP – Generic Aspects is the most promising tool No development since 2006 Runtime Weaving can be very interesting applied to Web Development Apply aspects in runtime without preprocessing Suitable for the crosscutting concerns: security, pooling and caching.

AOP can modularize crosscutting concerns in Web Applications.

Little AOP research on Web development.

All AOP PHP tools are on a very early stage of development.

GAP – Generic Aspects is the most promising tool

No development since 2006

Runtime Weaving can be very interesting applied to Web Development

Apply aspects in runtime without preprocessing

Suitable for the crosscutting concerns: security, pooling and caching.

Future Work Deeper research to find and treat properly specific web concerns. Classification of the concerns for the success of a web application. Use the knowledge acquired on this work to develop a new AOP PHP implementation

Deeper research to find and treat properly specific web concerns.

Classification of the concerns for the success of a web application.

Use the knowledge acquired on this work to develop a new AOP PHP implementation

Thanks for your attention! Questions?

Thanks for your attention! Questions?