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Introduction to Mule 4 for Mule 3 Users

This version of Mule reached its End of Life on May 2, 2023, when Extended Support ended.

Deployments of new applications to CloudHub that use this version of Mule are no longer allowed. Only in-place updates to applications are permitted.

MuleSoft recommends that you upgrade to the latest version of Mule 4 that is in Standard Support so that your applications run with the latest fixes and security enhancements.

If you are a user that already knows Mule 3 and recently migrated to Mule 4, review the following introduction to learn the main changes in Mule 4.

If you are an experienced Mule 4 user, go directly to our Mule Runtime documentation instead.

Mule 4 simplifies the expression language and reduces management complexity so that you can speed up the on-ramping process and deliver applications faster than in Mule 3.

Conceptually, you can think of Mule 4 as an evolution of Mule 3. Many of the core concepts are the same: applications, flows, connectors, DataWeave, and so on. However, because it is simpler, there is less to learn and less for you to manage.

This overview takes you through the high-level changes in Mule 4 so that you can quickly learn the basics. It covers these topics:

  • Mule Message
    The Mule Message structure has evolved to make it easier to work with properties and to provide more consistency across connectors.

  • Expression language
    The Mule Expression Language has been replaced with the DataWeave language so that you work with data and learn Mule more easily.

  • Connectors
    The approach to connectivity was unified in Mule 4. Mule 3 transports were replaced with new operation-oriented connectors that are easier to use, have better out-of-the-box defaults, and provide new advanced capabilities.

  • Error Handling
    Easier and more powerful error handling with a new Try scope.

  • DataWeave
    DataWeave includes minor changes to simplify the syntax and make it easier to learn.

  • Studio 7
    Features a simplified palette, improved Maven integration, and many other usability improvements.

  • Runtime engine
    The internal execution engine has been updated with a new self-tuning and non-blocking reactive engine. This allows for better performance and scalability out-of-the-box.