External jar available to all Jetty web services

2 min read 07-10-2024

External jar available to all Jetty web services

Making External JARs Accessible to All Your Jetty Web Services

Imagine this: You've built a robust, efficient library in a JAR file and you want to use it across all your Jetty web services. Instead of copying this JAR file into each individual web application, wouldn't it be great if you could make it readily available to all of them? This article explores how to achieve this, simplifying your development process and promoting code reusability.

The Challenge: Sharing Libraries across Jetty Web Services

The traditional approach involves including your custom JAR in each web application's WEB-INF/lib folder. This works, but it's repetitive, prone to errors, and makes managing dependencies difficult. Imagine having to update the JAR in every single web application whenever you make changes – it's a nightmare!

Solution: Leveraging Jetty's Shared Library Configuration

Jetty provides a powerful mechanism to address this challenge – the shared library. This allows you to configure a central location for external JARs, making them accessible to all your web applications. Here's how:

Centralize Your JAR: Place your external JAR in a designated directory. For example: /opt/jetty/shared/lib.
Configure the Shared Library: In your Jetty configuration file (jetty.xml or jetty-*.xml), define the shared library location. Here's a snippet:
```
<New id="SharedLibrary" class="org.eclipse.jetty.webapp.WebAppContext">
    <Set name="contextPath">/</Set>
    <Set name="war">path/to/your/war/file.war</Set>
    <Set name="extraClasspath"><SystemProperty name="java.ext.dirs"/></Set>
    <Set name="extractWAR">false</Set>
    <Set name="parentLoaderPriority">true</Set>
</New>
```
- extraClasspath: This is where you define the path to your shared JAR directory. The SystemProperty ensures that the java.ext.dirs system property is included, allowing you to use the Java extension mechanism.
Start Jetty: Restart your Jetty server after making these changes.

Understanding the Advantages

This approach offers significant benefits:

Reduced Redundancy: No need to copy the same JAR into each web application.
Simplified Management: Update the JAR in one location, and all your services instantly benefit.
Improved Organization: Centralized JAR management fosters a cleaner project structure.
Enhanced Code Reusability: Share libraries across multiple web applications, minimizing code duplication.

Additional Considerations

Dependency Management: You can also utilize dependency management tools like Maven or Gradle to handle the shared JARs, further automating the process.
Security: Be mindful of potential security issues when exposing JARs globally. Ensure your shared library is secure and the JARs are properly vetted.

Conclusion

By leveraging Jetty's shared library feature, you can streamline your development process and enhance the reusability of your code. This approach makes your projects more efficient, maintainable, and secure.

Remember to carefully consider security aspects and utilize dependency management tools to optimize your shared library setup.