Coherence FAQ

Table of Contents

• Question: Not able to start/join a cluster using the default multicast networking?
• Question: I’m getting IllegalAccessExceptions when running with JDK 17 (or newer)?
• Question: I’m getting java.io.InvalidClassException: filter status: REJECTED when using Coherence with Helidon 3.x and JDK 17. How do I resolve this?
• Question: Are there any articles/presentations/demos about Coherence?

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Question: Not able to start/join a cluster using the default multicast networking?

For example, if you are trying to start a cluster on a dev machine when connected to a VPN.

Answer: Start coherence using the following system properties:

-Dcoherence.ttl=0
-Djava.net.preferIPv4Stack=true
-Dcoherence.localhost=127.0.0.1
-Dcoherence.wka=127.0.0.1

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Question: I’m getting IllegalAccessExceptions when running with JDK 17 (or newer)?

Answer: At the moment, the following JVM options must be included to resolve this issue:

--add-opens=java.base/java.util=ALL-UNNAMED
--add-opens=java.base/java.nio=ALL-UNNAMED
--add-exports=java.base/jdk.internal.ref=ALL-UNNAMED
--add-exports=java.management/sun.management=ALL-UNNAMED
--add-opens=java.base/java.lang.invoke=ALL-UNNAMED
--add-opens=java.base/java.lang=ALL-UNNAMED

To debug these types of issues, you can also include --illegal-access=debug to provide additional details.

See Migrating from JDK 8 to Later JDK Releases

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Question: I’m getting java.io.InvalidClassException: filter status: REJECTED when using Coherence with Helidon 3.x and JDK 17. How do I resolve this?

Answer: This exception is raised due to the serialization filtering being enabled. To resolve this, add the following system property when starting the JVM:

-Djdk.serialFilter=*;!*

See Serialization Filtering for more details on this feature.

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Question: Are there any articles/presentations/demos about Coherence?

Presentations:

• Aleks Seović: Managing State in Elastic Microservices

• Managing State in Elastic Microservices | Jakarta Tech Talks - September 2020

• Scalable Microservices for Java using Helidon and Coherence CE by Aleks Seovic and Dmitry Alexandrov (JNation)

Articles:

• A Gentle Introduction to Coherence

• Hello Coherence, Part 1 (server-side implementation of To Do List with Helidon)

• Hello Coherence, Part 2 (front-end implementation with React and JavaFX)

• Hello Coherence, Part 3 (deployment to Kubernetes, scaling and monitoring)

• Hello, Coherence — Now with Micronaut! (server-side implementation of To Do List with Micronaut)

• Hello Coherence - Bootiful Spring (server-side implementation of To Do List with Spring Boot)

• Peek Inside Coherence with OpenTracing, Part 1

• Peek Inside Coherence with OpenTracing, Part 2

• Peek Inside Coherence with OpenTracing, Part 3

Demos:

Sock Shop - a full-fledged microservices app with 6 services. The demo comes in a variety of flavors:

• https://github.com/oracle/coherence-helidon-sockshop-sample

• https://github.com/oracle/coherence-micronaut-sockshop-sample

• https://github.com/oracle/coherence-spring-sockshop-sample

ToDo List - A simple ToDo application that demonstrated using various technologies and languages

• https://github.com/coherence-community/todo-list-example