Custom module development: background and prerequisites

You can create custom modules in the Developer Portal to extend functionality. The following information provides a getting started developer guide to custom module development.

Custom modules are written in PHP, which is an open source server-side scripting language that is used for creating dynamic web pages. For general information on the Drupal tools for PHP development, see Custom module development: an introduction to Drupal tools for PHP development.

The following sections provide an overview of custom module development, with links to learn more about the required development languages and concepts. Creating custom modules affects the source of your Developer Portal site, so it is recommended that you gain Drupal experience and PHP knowledge before you start creating modules.

  • You are not permitted to include any IBM® API Connect modules within any custom modules that you create. Also, directly editing any API Connect themes, modules, included modules, or Drupal core on the file system is not permitted or supported, as edited versions of these files are overwritten when a fix pack or iFix is installed.
  • All custom development is your responsibility. Although the use of custom modules and themes is supported, IBM API Connect do not provide support in their development or modification.

Object-Oriented Programming (OOP)

OOP is established as best practice for development, so ensure your knowledge of OOP is good. The PHP documentation on Classes and Objects is a good place to start. For a general overview of PHP best practices, see PHP The Right Way. The following resources are also helpful:
Drupal also uses some common design patterns, so you need to ensure you have a basic understanding of these. See the following pattern resources:

PHP namespaces

You must be familiar with the concept of namespaces in PHP. In most cases, the Drupal code is namespaced based on the module that code belongs to.

For example, the namespace for block.module is:
namespace Drupal\block;

When you create Drupal modules, it is important to consider that PHP has a global namespace, and that function names must be unique. You are recommended to prefix the name of any methods with the module name.

For example, if you have a module that is named custom_module, a create method within it is called custom_module_create().

For more information about namespaces, see the following resources:

Dependency injection

It is important that you have a baseline understanding of dependency injection. Drupal makes heavy use of this concept, so you will need this understanding to be able to access and make use of many of the core APIs.

To find out more about dependency injection, see Dependency Injection (on, as well as the additional articles that are linked to on that page. See also Services and dependency injection in Drupal (on


Symfony is a set of reusable PHP components and a PHP framework for web projects. Drupal borrows from this framework in order to reduce code duplication across various PHP projects. Much of the code that Drupal uses to handle routing, sessions, and the services container, amongst other things, is borrowed from Symfony.

To understand how Symfony works, see the Symfony Documentation on

Other useful resources

  • Drupal API Annotations - list of the different annotation types that Drupal uses for plugin discovery, and to provide additional context/meta-data for the code that's being executed.
  • Plugin API overview - overview about how plugins are used in Drupal.