Mule 3 to Mule 4 Cheat Sheet

Here’s the description of some action items that require analysis and migration:

• Configuration properties 

Definition of loading of properties differs between mule versions.

• HTTP connectors

There are differences in the connector, especially when handling multipart projects.

• Replace MEL with DataWeave

MEL is no longer supported; DataWeave 2.0 is now the expression language.

• Refactor of transformers

Transformers (Ex. <object-to-string />, <object-to-json>) are no longer supported.

• DataWeave 1.0 to 2.0

Syntax and functions differ from 1.0 to 2.0; this requires analysis and translation.

• Object Store

It uses a new connector, which will require changes.

• Exception handling

Mule 4 uses a new system called Error Handlers.

• Message structure

Due to changes in the message structure, attachments, session properties, inbound, outbound, invocation properties are no longer supported.

• Poll component

In Mule 4, the <poll> element is replaced with the <scheduler> element.

• Java calls

Interoperability with Java is now done through the Java module.

• Spring beans

Instead of defining Spring beans directly in the application, one needs to use the Spring Module.

• Custom Aggregators

In scatter-gather, the java class definition is no longer needed and is replaced by DataWeave.

• Until-Successful component

Properties for configuring this component are changed between versions, requiring refactoring.

• Splitter/Aggregator

Splitters are no longer available in Mule 4. This needs to be refactored and replaced; aggregators have different behaviour.

• For Each Scope

In Mule 4, the transformation of the incoming collection to Java is unnecessary.

• Filters

Filters are no longer available; this needs to be replaced by the Validation Module.

• Enrichers

The message enricher is no longer available and required to be used within each component call using their target parameter.

• Policies

There are changes in the structure and has been packaged that requires refactoring.

• API kit

Changes to HTTP Listener, Auto discovery configuration, validation configuration is required.

• Other components that require migration

File Connector

Email Connector

AMQP Connector

FTP and SFTP Connector

Database Connector

Scripting Connector

Validation Connector

VM Connector

Would like to know more about the migration? Let’s connect!