PHP and MySQL for Scalable Web Applications

Scalability is an important consideration when building web applications. Scalability generally refers to the capability to handle a growing traffic load. Traditionally, PHP hasn’t been considered overly scalable. However, that has more to do with how PHP applications have been written in the past rather than any limitation in PHP itself. WordPress and Drupal are both excellent examples of scalable applications built in PHP. Scaling your web application with PHP and MySQL simply involves following some of the practices used in WordPress and Drupal.

Employ Modular Design
Building a modular application is one sure way of scaling your web application with PHP and MySQL. If you examine the code in WordPress, you’ll find that it has been built in a very modular fashion. All the database code in one place. All the layout and rendering code is in another.

There are places in the modules to add additional functions called hooks and filters. These make it easy to extend WordPress without recoding parts of the underlying application. This modular architecture makes it easy to scale a web application with PHP and MySQL.

Maintain Layers of Abstraction
Abstraction is another important consideration. The higher level interfaces in your code should abstract things like access to the database. The functions that are retrieving data should have functions that simply “get” the data without understanding the underlying details. This is important for scaling your web application with PHP & MySQL because you won’t know in advance how the database is deployed. You might initially deploy your PHP code on the same server as your MySQL database. Later, MySQL might be on a separate server. And even later, you may be load balancing among several MySQL servers. Changing the underlying architecture should require only minimum changes to your PHP code. Design with this in mind and you’ll have no problems scaling your web app with PHP and MySQL.

Use a PHP Framework
Of course, the easiest way to do both of the above things and ensure the scalability of your PHP and MySQL web application is to use a framework. There are many PHP frameworks that follow the model-view-controller pattern used in systems like Ruby on Rails. These frameworks already provide a modular system and strong abstraction of the database layer. Some of them also support caching and handle database driven sessions to maximize your ability to scale your web application with PHP and MySQL.

Cache, Cache, Cache!
Speaking of caching, a common technique for scaling web applications with PHP and MySQL is to use a caching system for data or page content that does not change frequently. Think about how you might use caching in the future as you develop your application. If you can separate data and pages that can be cached from those that cannot, you’ll have an easier time using a cache to scale your web application with PHP and MySQL.

Scalability is an important consideration in web development today. There are a number of techniques for scaling your web application with PHP and MySQL. Modular design, abstracting the underlying details, using a framework and considering the impact of caching will all help you scale your web application with PHP and MySQL.