Introduction:
Migrating a legacy application to a newer Java version can be a challenging task, and I recently faced this challenge while migrating the application from Java 8 to Java 17. The migration wasn’t smooth, as I encountered two key hurdles. In this post, I’ll walk you through both of them.

1. JAX-WS Removal
One of the first roadblocks I hit during the migration was the removal of JAX-WS (Java API for XML Web Services). this API was deprecated in Java 9, removed in Java 11, and by extension Java 17, no longer includes JAX-WS, which our application was using to call web services. This caused the application to break whenever it attempted to communicate with the web services.

Solution:
To resolve this issue, I use the Metro JAX-WS library as a replacement. Metro JAX-WS is a standalone library that provides the same functionality as the removed JAX-WS. By integrating this library, I was able to restore the web services communication in the application, ensuring it continued to function smoothly.

2. XStream API Compatibility
The second challenge involved the XStream API, which our application was using this API for marshaling and unmarshaling Java objects to and from XML. The current version of XStream (1.4.20) turned out to be incompatible with Java 17 due to the strong encapsulation introduced in the JDK 17.

Solution:
To address this, I switched from XStream API to JAXB (Java Architecture for XML Binding) API. JAXB is well-supported in Java and works seamlessly with Java 17. After migrating the code to use JAXB, the application was able to handle XML operations without any issues.

Conclusion
Migrating from Java 8 to Java 17 was not without its challenges, but by tackling issues like above, I was able to successfully migrate the application. These challenges taught me valuable lessons about adapting to new versions of Java and finding suitable alternatives when existing solutions are no longer supported.

I hope my experience helps others who might be facing similar issues during their migration journey!

More on below links!!

https://docs.oracle.com/en/java/javase/17/migrate/migrating-jdk-8-later-jdk-releases.html

https://x-stream.github.io/download.html

https://javaee.github.io/jaxb-v2