Class loader isolation and SDK module exports
How Mule 4 isolates the runtime, applications, domains and modules behind declared APIs, how artifacts and Mule SDK modules export packages and resources, which library clashes isolation cannot prevent, and how connectors reach application dependencies.
Design Mule applications making effective use of the implications of the Mule 4 class loader isolation of Mule modules.
~6 min read · 7 practice questions
What the exam expects
- Explain why Mule 4 isolates artifacts and what an artifact's filtering class loader lets other artifacts see.
- Declare an artifact's public API with exported packages and exported resources in
mule-artifact.json. - Predict which packages a Java SDK module exports, and structure packages so internal classes stay hidden.
- Recognize library clashes that isolation cannot prevent, and design module signatures to avoid them.
- Choose how a connector gets access to an application dependency.
Artifact: an independently released unit such as the runtime, an application, a domain, a policy or an extension. Exported package: a Java package an artifact makes visible to others. Filtering class loader: the wrapper that enforces what other artifacts can see. Mule SDK: the Java or XML framework for building Mule 4 modules (Class-loading Isolation, SDKs Overview).
Sources for this section (2)
Key facts
- Detail
- Not visible from other artifacts
- Detail
- Whole packages; individual classes cannot be exported
- Detail
exportedResourcesinmule-artifact.json
- Detail
- Configuration, connection, input and return types
@Export- Detail
- Takes classes, exports their whole package
- Detail
- Two modules exporting one package fail the app
- Detail
- Same-named classes from different versions still clash
- Detail
- Invisible to connectors unless shared or added as plugin dependencies
- Detail
- Mule 4 APIs follow Semantic Versioning 2.0.0
- Which three APIs does Mule 4 provide as its extension points?
- When Studio configures the connection driver for a Database connector, how does the driver reach the project?
- Why does MuleSoft suggest
.api.and.internal.in package names? - Which artifact types does the Export Resources page say hold resources that are internal unless exported?
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