Manual Migration Process
After learning how to prepare for a migration, it is important to understand the high-level migration steps.
- Note
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For an assisted migration with the Mule Migration Assistant, start instead from the user documentation (on GitHub), which links to the MMA user documentation.
For a completely manual migration:
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Add all required modules, such as the Database connector, to the Anypoint Studio 7 palette.
Notes:
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You can add modules through the Studio 7 palette. Other modules are available in Anypoint Exchange.
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All Mule projects are Mavenized by default when you add the modules to your project.
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Migrate all the global configurations.
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Migrate configuration properties.
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Learn how the components work in Mule 4 to see what has changed from Mule 3.
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Understand how changes to the Mule message structure (attributes, payload, and variables) affect your configurations. See Introduction to Mule 4: The Mule Message.
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Update your expressions and scripts to DataWeave version 2:
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Be aware of changes between DataWeave 1 and DataWeave 2, for example, importing specific function modules and understanding syntax changes. See Migrating from DataWeave 1.0 to 2.x.
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Change MEL expressions to DataWeave 2, for example, in an connector or Choice component. See Migrating MEL to DataWeave.
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Update all exception handling to Mule 4 with the new exception types that are available.
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If you are working with APIs, understand how to set HTTP status codes.