A Magento extension is a package of code responsible for achieving a
specific functionality in Magento. From a technical perspective, it’s a directory
containing PHP and XML files in blocks, controllers, helpers, and models relating to a specific
business feature. If you browse through Magento’s Developer Documentation, you will
find the term “module” used in the same context intermittently. While both a module
and an extension are similar, the term module often refers to core code, i.e., code that is part
of Magento itself. In contrast, an extension always refers to a packageable component that can
extend and customize Magento functionality. Extensions can be distributed and installed on
multiple stores to help achieve specific functionality.
Throughout the years, the primary focus behind the development of
Magento has been maximizing its extensibility. And at the very core of Magento’s
development model is the practice of extending or replacing core code instead of editing it.
This strategy helps preserve the integrity of Magento’s code and allows merchants and
developers to customize Magento to their requirements. Magento’s code follows most of the
code further helps ensure their codebase is sound.
In addition to this, Magento also relies on many well-known
architectural and programming structures and incorporates widely recognized and time-tested
software architecture constructs called design patterns in its product architecture. Of these,
the MVC (model-view-controller) pattern is the one that is most relevant to extension
development. The use of these structures and design patterns helps PHP developers orient
themselves with developmental issues that could arise when developing extensions or working with
Magento. Easier identification of these issues helps reduce the learning curve for new Magento
The concept of modularity has always been central to Magento
extension development. By packaging code into modules, an extension is self-contained, making it
possible to modify or replace it without adversely affecting other areas of the code. Keeping a
feature limited to a single extension helps reduce the chances of a domino effect from occurring
throughout the codebase when its code is changed. The purpose of any extension is to provide
specific features by extending existing functionality or implementing new ones. Designing each
extension to work independently mitigates the risk of an extension conflicting with another and
allows them to work in tandem instead.
You will find all files related to an extension in a
vendor directory with the following PSR-0 compliant format —
usually any one of three values — module, theme, or language, depending on the extension
and functionality. When creating a new module for distribution, you create the
app/code/<vendor>/<type>-<module-name> directory first and then other
required directories within it. A
registration.php file is a must in every
extension’s root folder, along with any dependencies of the extension, its name, and
version placed in the
etc/module.xml file in the same folder.
Magento Marketplace extensions
By creating a platform built for extensibility, Magento has fueled
the rise of a rich product ecosystem by enabling developers to innovate and create using the
platform. Magento has an official marketplace called the Magento Marketplace, where platform users can
purchase and download third-party extensions and themes to extend their online stores. Magento
has a robust Extension
Quality Program that combines Magento expertise, developmental guidelines, and
verification tools to ensure all extensions on its marketplace meet their coding standards and
follow best practices.
In addition to the extensions on its marketplace, Magento comes
pre-packaged with additional third-party extensions out of the box. These extensions are called
Vendor Bundled Extensions. They’re thoroughly tested before being included with any
supported version of Magento. Installing Magento will also install these extensions by default.
However, to use them, store owners are often required to set up separate accounts with the
vendors. Some of the Vendor Bundled Extensions you’ll find packaged with the latest
Magento versions are Amazon Pay, dotdigital, Klarna, Vertex, and Yotpo.
Magento’s extensive global community of developers means
there’s no shortage of ready-to-use third-party extensions on the market today. As a
result, many store owners often go overboard using third-party extensions as they’re cheap
and easily accessible. However, overuse of such extensions and especially the use of poorly
coded extensions can hamper a store’s performance. Judicial use of extensions is strongly
advisable, and whenever possible, it’s best to get extensions custom-built. In situations
where custom-building isn’t feasible, third-party ready-to-use extensions must be tested
before deployment on live stores and tweaked to use only the required functionality. Removing
unwanted functionality will help minimize the usage of additional resources and limit its
effects, if any, on a store’s performance.