How Can I Extend the Functionality of the Mendix Platform?

The Mendix Runtime can be extended in number of different ways. The sections below present details on extending via the Mendix Connector Kit, Java actions, JavaScript widgets, Java request handlers, and data storage.

The Mendix IDE Studio Pro can also be extended by leveraging the extensibility API which you can read about in Studio Pro Extensibility, below.

Java Actions & Connector Kit

Java actions enable creating reusable microflow activities that you can use in any microflow. You can create Java actions specific to your application, and you can also bundle them in a module so that they can be reused in other projects and by other developers.

Java actions are often used to integrate with external systems (hence the term “connectors”), but you are not limited to the integration use case. In fact, you can do anything you can think of in Java, including using most existing (open-source) Java libraries. This enables you to provide plugins for any type of functionality you need.

To ensure your fellow team members and even external users can easily use custom Java actions, they are completely integrated into the microflow editor experience in Mendix Studio Pro. Other Mendix developers will not see the difference between a standard microflow activity and a custom Java action.

The following image is taken from an example used in How to Build Microflow Actions Using the Mendix Connector Kit in the Mendix Studio Pro How-to’s. As you can see, the Join objects in list custom action looks like any other microflow activity, with an icon and user-friendly parameters:

All custom Java actions can be made available in the microflow toolbox, which eases discovery and use by non-technical Mendix users. In fact, users can just drag activities from the toolbox to their microflow without knowing that it is implemented as a custom Java action. To expose a Java action in the toolbox, just select the Expose as microflow action check box, as illustrated in this video:

Within the Java action implementation, you can use the Mendix Runtime APIs to create a tight integration between the Mendix objects and your Java code.


For more information on using custom Java actions, explore this Mendix documentation:

Pluggable Widgets

You can extend the front-end of your Mendix applications by building custom widgets based on JavaScript or TypeScript. For more information, see the Pluggable Widgets section of Front-End.

Pluggable Actions

For creating custom application logic, Mendix enables developers to build customs nanofow actions. These pluggable nanoflow actions (which are called JavaScript actions in Studio Pro) can be used to leverage device capabilities or perform any type of logic in the client. For more information, see the Pluggable Nanoflow Actions section of Front-End.

Java Request Handlers

The Java Request Handler API enables you to create a custom HTTP endpoint implementation in Java. A request handler is basically a Java method that receives an HTTP request, uses the input, and then sends a response to the caller. This can be useful in many situations, such as custom authentication, deep links into specific pages, and custom protocol implementations. Implementation of the request handler is not limited to Java, as you can run Mendix microflows and activities from the Java implementation.

Please note that with the availability of native REST publishing, the need for custom Java request handlers has been greatly reduced.

Data Storage

All the query languages supported by Mendix can be used through a Java API. This includes XPath, OQL, and SQL:

XPath and OQL are both portable, meaning their behavior will be identical no matter what database you use. SQL enables using all the features of your chosen database. One scenario for this is to use database-specific indexes to increase the performance of your queries.

You can use Mendix’s Java APIs to register entity event listeners for all your entities. This can be used to extract auditing information or to do a real-time export of all the data changes to an external system.

For more information, see this Mendix documentation:

How Can I Provide Reusable Connectors to Third-Party Services?

Generic connectors can be easily shared with other developers and companies. You can export a connector module from Mendix Studio Pro that can then be imported into other Mendix app projects. The connector module can also be uploaded to the Mendix Marketplace – either to the Public Marketplace so anyone can use it, or to your company’s Private Marketplace so that only developers in your company can reuse it. For more information, see How to Share Marketplace Content in the Mendix Developer Portal Guide.

Connectors include everything you need to use them, like microflow activities, logic, domain models, Java code, and any required Java libraries. This complexity will not be visible to the users of your connector. They can simply drag your custom microflow activities from the toolbox into any microflow to use your connector.

Here is an example of a connector:


Studio Pro Extensibility

Next to design time extensibility, Mendix also offers IDE extensibility which allows you to extend Studio Pro, the Mendix IDE.

The Extensibility API allows you to extend Studio Pro using C# and web technology like React and Typescript. The API allows you to not only extend the capabilities of Studio Pro with functionality that can help with the developer experience, but also expand the design time language with tailored editors and domain-specific languages.
The API provides access to the app that is open in Studio Pro, allowing you to perform any manipulations at design time.

What Tooling Does Mendix Integrate With?

Mendix provides seamless integration with a number of tools that developers use:

  • By selecting Deploy for Eclipse in Mendix Studio Pro, your Mendix app project will be made compatible with Eclipse, which means you can run and debug your app from Eclipse. You will also have access to the Java source code, where you can implement custom Java actions. For more information, see the Mendix documentation on  Using Eclipse and How to Debug Java actions.
  • Many Mendix developers use IntelliJ IDEA. IntelliJ enables you to import Eclipse projects, so by selecting Deploy for Eclipse in Mendix Studio Pro, you will also be able to do all your custom Java actions coding in IntelliJ.
  • Widget developers can benefit from building Pluggable Widgets.

What Open Standards Does Mendix Support?

Mendix strongly adopts open standards in order to support the seamless integration of the platform and applications built on the platform as well as to support the exchange of design artifacts.

This is a short overview of the open standards and technologies used in the Mendix Platform:

  • Application data can be stored in a large number of mainstream relational database management systems. Mendix uses the SQL standard for defining and manipulating your domain model and data. Throughout the years, SQL has proven itself a flexible, multi-purpose, and future-proof data language. So much so, even NoSQL databases are embracing SQL as the default way to retrieve data.
  • The Mendix Runtime is implemented using Scala and Java, and it runs on the Java Virtual Machine (JVM). Similar to SQL, the JVM offers a flexible, multi-purpose, and future-proof platform. Java enables us to run the Mendix Platform on a large number of systems and cloud platforms. The JVM runtime is flexible for a large number of programming languages. This enables combining a proven language like Java with the functional features of an innovative language like Scala.
  • Mendix provides support for many open standards relevant for integration, including web services, SOAP, WSDL, XML Schema, REST, JSON, Swagger, OpenAPI, and OData.
  • For the front-end, Mendix supports a number of open standards and also a number of de-facto standards, such as web pages being rendered using HTML5, CSS3, and React.
  • Mendix has embraced best practices for software innovation management through Agile methodologies. The Mendix Platform provides the tools required for the most commonly used Agile methodology—which is Scrum—so that you can manage your Mendix application projects.
  • For hosting, Mendix has embraced open and de-facto hosting technologies like Linux, Docker, Kubernetes, and Cloud Foundry.