A software framework provides the skeleton of an application that can be customized by an application developer. Like software libraries, software frameworks aid the software developer by containing source code that solves problems for a given domain and provides a simple API. However, while a code library acts like a servant to other programs, software frameworks reverse the master/servant relationship. This reversal, called inversion of control, expresses the essence of software frameworks. A web application framework is a software framework that is designed to support the development of dynamic websites, Web applications and Web services. The framework aims to alleviate the overhead associated with common activities used in Web development. For example, many frameworks provide libraries for database access, templating frameworks and session management, and often promote code reuse.Zend Framework

Dragos-Paul POP

English

Research Papers in Economics

INTRODUCTION TO ZEND FRAMEWORK 
 
Dragos-Paul POP  
Faculty of Computer Science for Business Management, 
 Romanian – American University, Bucharest, Romania 
 
 
ABSTRACT 
     A  software framework  provides the skeleton of an application that can be customized by an 
application developer. Like software libraries, software frameworks aid the software developer by 
containing source code that solves problems for a given domain and provides a simple API. However, 
while a code library acts like a servant to other programs, software frameworks reverse the 
master/servant relationship. This reversal, called inversion of control, expresses the essence of software 
frameworks. 
     A web application framework is a software framework that is designed to support the development of 
dynamic websites, Web applications and Web services. The framework aims to alleviate the overhead 
associated with common activities used in Web development. For example, many frameworks provide 
libraries for database access, templating frameworks and session management, and often promote code 
reuse. 
 
1. INTRODUCING ZEND FRAMEWORK 
     Zend Framework was designed and built to improve developer productivity. Unlike other frameworks 
that require large configuration files to work, most aspects of a Zend Framework application can be 
defined at runtime using simple PHP commands. This saves developers time because instead of complex 
configuration files controlling every aspect of the application, you only configure the parts that deviate 
from the norm. 
     The framework was written entirely in PHP 5. It will not run on any server that does not have a 
minimum of PHP 5.1.4 installed. The current version has been thoroughly tested and over 80% of the 
code is covered by test cases using PHPUnit. 
     Zend Framework was built on several key concepts: 
• Best Practices 
• Community Driven 
• Extensionability 
• Extreme Simplicity 
• Liberal BSD License 
     Unlike many other frameworks available for PHP, Zend Framework chose not to implement the 
ActiveRecord pattern and not to ship with an Object-Relation Mapper (ORM). Contrary to popular 
opinion, this was not an oversight but a conscious decision by the framework team. 
     The Zend Framework is really a hybrid framework and as such can be used in amuch larger range of 
projects than strict “application frameworks”. While many components in Zend Framework can be used 
stand-alone like a component library, it is, at its core an implementation of the “Model-View-Controller” 
(MVC) pattern. 
 
2. HISTORY AND PHILOSOPHY 
     Zend Framework was conceived in early 2005 while many new frameworks, such as Ruby on Rails 
and the Spring Framework, were gaining popularity in the web development community. ZF was publicly 
announced at the first Zend Conference. At the same time, no widely used framework had been made 
available to the PHP community to fulfill similar web development needs. The designers of Zend 
Framework sought to combine the ease-of-use and rapid application development (RAD) features of these new frameworks with the simplicity, openness, and real-world practicality that is highly valued in the 
PHP community. 
     Typically, specific development usage scenarios are implemented using more generalized software 
components through automatic configuration and/or code generation. In previous releases, the Zend 
Framework community has opted to complete development and testing of these underlying components 
before starting work on simplifying development tasks such as database migrations, generating 
scaffolding, and project creation and configuration. This practice has been the subject of some criticism 
since some functionality considered by many as necessary for a general release for modern web 
application frameworks is slated for future Zend Framework releases. Many ZF users, however, have 
found such generalized software components more reusable and extensible in implementing their 
applications. Zend Framework also seeks to promote web development best practices in the PHP 
community; conventions are not as commonly used in ZF as in many other frameworks, rather 
suggestions are put forth by setting reasonable defaults that can be overridden for each ZF application’s 
specific requirements. 
 
3. THE ZEND FRAMEWORK COMMUNITY 
     Possibly the greatest asset that Zend Framework has is its community. The community around Zend 
Framework is growing daily. While several of the developers working on Zend Framework actually work 
for Zend, the majority of them do not. 
     The process of proposing and reviewing new components is open and community driven. Because the 
community is comprised of both beginner and advanced programmers, there is never any shortage of help 
for new adopters. Whether you prefer mailing lists, forums or chat, Zend Framework community is 
always there and willing to help. The community realized early on that with any framework, getting 
started is the hardest part. Therefore, there are numerous tutorials and quickstart guides to help both 
novice and advanced users get up and running. The project Web site (http://framework.zend.com) houses 
not only the documentation and downloads for the project but a full bug-tracking/ticketing system that 
allows anyone to register and submit bugs. This level of openness helps them meet the first goal of the 
project, “Community Driven”. 
 
4. THE ZEND FRAMEWORK LICENSE AND INTELLECTUAL PROPERTY CONCERNS 
     All contributors to Zend Framework sign a “Contributors License Agreement” stating that the code 
they are contributing is IP clean. The practice and agreement is similar in nature to that required by the 
Apache group. This was done not as an exclusionary practice but to give peace of mind to companies 
considering adopting Zend Framework to build commercial applications. To facilitate its adoption by both 
open source projects as well as commercial entities, Zend Framework was released under a BSD style 
license. This allows for the framework to be used in the widest possible range of projects and puts the 
fewest restrictions on adopters. A complete copy of the BSD License can be found on Zend Framework 
Web site (http://framework.zend.com/license). 
 
5. MVC 
     MVC, like so many great things in computers, came out of Xerox’s PARC in 1978-1979. These days 
MVC is a common pattern for frameworks to implement because it separates the code into three logical 
groups. 
•  The model can be thought of as the representation of the data that your application will utilize. In 
simple terms, the model can be thought of as the “nouns” of your project. An “order”, a “member”, an 
“article”, these are all examples of potential models in your system. 
•  The view contains all the display logic. In the majority of PHP applications, this means the HTML 
output of your application. However, even in web applications, this can mean a variety of output 
formats. Whatever the format, the view is responsible for the merging of the data from the model and 
the actions of the controller and sending it to the proper client. (In most cases with PHP, that’s a web 
browser). •  The controller is responsible for the domain logic in your applications. It represents the verbs or 
events. “Add,” “edit” and “submit” are all actions your application can take. The controller embodies 
these actions for you. There are many good examples of MVC-implemented frameworks in PHP. If 
that were its only selling point then Zend Framework would be just another framework in an ever-
growing list. Zend Framework however, separates itself by allowing you to pull pieces of it out and 
use them independently. The Zend Framework teams calls this “use at will” architecture. Most of the 
components that are not part of the MVC core can be pulled out and used as “standalone” components 
in your application. 
 
     Examples of the “use at will” components are 
• Zend_Cache 
• Zend Rest_Client 
• Zend_Feed 
• Zend_Log 
     Each of these can be used independently of the framework itself and that means their functionality can 
be easily incorporated into existing applications. Simply put, if all you need is a single component, you 
can use just that component. However when the job requires a full framework, you have that option also.  
     It should be noted here though that MVC is not something you can retrofit into an existing application. 
If you are maintaining existing code, the component library aspect of Zend Framework will be of much 
more interest to you because you can easily integrate the pieces you need without disturbing your existing 
legacy code. However, if you are building in “green fields” then the MVC aspect of Zend Framework will 
be of more interest because you have the luxury of building from scratch. 
 
6. FEATURES 
•  All components are fully object-oriented PHP 5 and are E STRICT compliant 
•  Use-at-will architecture with loosely coupled components and minimal interdependencies 
•  Extensible MVC implementation supporting layouts and PHP-based templates by default 
•  Flexible Table Gateway implementation for accessing data from a relational database in an object-
oriented environment 
•  Support for multiple database systems and vendors, including MySQL, Oracle, IBM DB2, Microsoft 
SQL Server, PostgreSQL, SQLite, and Informix Dynamic Server 
•  Authentication and ACL-based authorization using a variety of backend systems 
•  Data filtering and validation for enhanced application security 
•  Session management 
•  Configuration component to promote consistent configuration management throughout the Zend 
Framework and ZF applications 
•  Email composition and delivery, retrieval via mbox, Maildir, POP3 and IMAP4 
•  Indexing and search that supports the Lucene index file format 
•  Internationalization and localization 
•  Creation of forms using PHP, configuration files, or XML 
•  Identity 2.0 technologies such as Microsoft InfoCard and OpenID 
•  Multiple formats for web services, including XML-RPC, REST, and Google GData. 
•  Flexible caching sub-system with support for many types of backends, such as memory or a file 
system. 
•  Simple logging component inspired by log4j 
•  Native-PHP component for reading, updating, and creating PDF documents 
•  Serialization of PHP data structures to and from JSON to facilitate AJAX development 
•  API for consuming RSS and Atom feeds 
•  Client libraries for many web services out of the box, including Amazon E-Commerce Service , 
Akismet, del.icio.us, Flickr, StrikeIron, Yahoo!, Audioscrobbler, and Simpy. 
7. ORGANIZATIONS USING ZEND FRAMEWORK: •  brainbits 
•  Berlin Museums 
•  Digital Sublimity 
•  Eurotransplant 
•  GNU/Linux Matters for Poliglota. 
•  IBM 
•  Marseille City School System 
•  Nokia 
•  Right Media 
•  Magento 
•  Shoppingads 
•  Australia Week 
REFERENCES 
[1]   Cal Evans, “php|architect’s Guide to Programming with Zend Framework”, Marco Tabini & 
Associates, Inc. 2008 
[2]   Wikipedia, http://en.wikipedia.org/wiki /Zend_Framework 
[3]    Zend, http://framework.zend.com/ 
[4]  IBM, http://www.ibm.com/developerw /opensource/library/os-php-zend1/  

php|architect’s Guide to Programming with Zend Framework”,

INTRODUCTION TO ZEND FRAMEWORK

http://www.rebe.rau.ro/RePEc/rau/jisomg/FA08/JISOM-FA08-A18.pdf

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