How to Migrate from Java EE to Jakarta EE — Tips and Best Practices

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Introduction

With the transition from Java EE to Jakarta EE, many developers are looking to migrate their applications to the new platform. Jakarta EE, managed by the Eclipse Foundation, offers improved features and performance, making it a worthy upgrade for your projects. In this article, we’ll go over the key steps to migrate from Java EE to Jakarta EE, along with some tips and best practices to make the process as smooth as possible.

Understand the Key Differences between Java EE and Jakarta EE

The transition from Java EE to Jakarta EE involves several key differences that are essential to grasp before initiating the migration process. The most significant change is the shift in the namespace from javax.* to jakarta.*. This alteration impacts all the Java EE APIs which are now consolidated under the Jakarta EE umbrella. Understanding this change is crucial as it affects every aspect of application development, from annotations and imports in your code to configuration files and dependencies.

Beyond the namespace changes, Jakarta EE also introduces improvements and modern approaches to enterprise Java, including improvements in cloud-native application development capabilities, updates to microservices architectures, and better integrations with modern CI/CD tools. It supports a more open and collaborative development environment compared to Java EE, which was primarily controlled by Oracle.

Prepare Your Environment

First, ensure that you have the necessary tools and software installed:

• JDK 8 or higher (Jakarta EE supports JDK 8 and 11)
• Jakarta EE compatible application server (e.g., Payara, WildFly, Open Liberty)
• IDE with Jakarta EE support (e.g., Eclipse, IntelliJ IDEA)

Update Your Dependencies

Updating dependencies is a critical step in migrating to Jakarta EE as it ensures that your application utilizes the latest libraries, which are compliant with the new jakarta.* namespace. This process involves replacing all the Java EE dependencies with their respective Jakarta EE counterparts in your project’s build configuration files, such as Maven or Gradle.

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For Maven projects, modify the pom.xml to include the Jakarta EE libraries. Here’s how you can update the dependencies in your Maven configuration:

<dependency>
    <groupId>jakarta.platform</groupId>
    <artifactId>jakarta.jakartaee-api</artifactId>
    <version>9.1.0</version>
    <scope>provided</scope>
</dependency>

For Gradle projects, you will need to update your build.gradle file similarly. Ensure that you use the providedCompile scope to avoid including these APIs in the final artifact, as they are typically provided by the application server:

dependencies {
    providedCompile 'jakarta.platform:jakarta.jakartaee-api:9.1.0'
}

It’s important to review all project dependencies for any indirect usage of old Java EE APIs and update them accordingly. This might require checking third-party libraries or frameworks that are being used in your project to ensure they have been updated to support Jakarta EE.

Refactor Your Code

Refactoring your code to use the new jakarta.* namespace is perhaps the most labor-intensive part of the migration. This step involves updating import statements and fully-qualified class names throughout your codebase.

1. Manual Refactoring: This can be done manually but is only recommended for smaller projects due to its error-prone nature. You would need to search and replace all occurrences of javax.* with jakarta.* in your source files.
2. Automated Migration Tools: For larger codebases, consider using an automated migration tool to streamline the process. The Eclipse Transformer, for example, is a comprehensive tool designed for this purpose. It can be executed as follows:

java -jar org.eclipse.transformer.cli-0.4.0-SNAPSHOT-all.jar \
  -i input_directory \
  -o output_directory \
  -x jakarta-renames.properties \
  -t jakarta-direct.properties

This tool scans all files in the input directory, transforms them according to the specified rename and direct properties, and outputs the transformed files into the output directory.

Test Your Application

Testing is a critical phase in the migration process to ensure that the application functions as expected after the transition to Jakarta EE. Here’s how you can thoroughly test your application:

1. Unit Testing: Begin with unit tests to verify that individual components work correctly with the new jakarta.* namespaces. This involves testing all the classes and methods independently to ensure they perform as expected.
2. Integration Testing: After unit testing, perform integration tests. These tests are crucial as they help confirm that different parts of your application work together as intended. This includes testing interactions with databases, other services, and integration with middleware.
3. System Testing: Conduct system-wide tests to evaluate the application’s performance and behavior in an environment that mimics production.
4. Performance Testing: It’s also essential to test how the application performs under load. Tools like Apache JMeter can be used to simulate multiple requests to the application and measure response times and throughput.
5. Regression Testing: Ensure that features that were working before the migration are still operational. This helps in identifying any new issues that might have been introduced during the namespace change.
6. User Acceptance Testing (UAT): Finally, involve end-users to perform UAT. This step is vital to confirm that the application meets the business requirements and is ready for deployment.

Deploy Your Application to the Jakarta EE Compatible Server

Deploying your application on a Jakarta EE-compatible server is the next step after testing. Here are the steps involved:

1. Choose a Compatible Server: First, ensure that your chosen server supports Jakarta EE. Commonly used servers include Payara, WildFly, and Open Liberty.
2. Server Configuration: Configure the server according to the needs of your application. This might include setting up data sources, JMS providers, and integrating any required external systems.
3. Deployment: Deploy your application to the server. This can typically be done through the server’s administration console, command line tools, or through an integrated development environment (IDE) that supports deployment.
4. Verify Deployment: After deployment, verify that the application starts up correctly and that there are no startup errors in the server logs.
5. Smoke Testing: Perform a quick round of tests to ensure that all major functionalities are working as expected.

Monitor and Optimize Your Application

Once your application is deployed, ongoing monitoring and optimization are crucial to maintain and improve its performance:

1. Monitoring Tools: Utilize monitoring tools to continuously observe the application’s performance. Tools like Prometheus, Grafana, or the monitoring capabilities of your application server can provide insights into throughput, memory usage, response times, and more.
2. Log Analysis: Keep an eye on server logs for any errors or unusual activity. Log management tools can help in aggregating and analyzing logs to detect potential issues early.
3. Performance Tuning: Based on the monitoring data, adjust configurations to optimize performance. This might involve tuning JVM settings, optimizing database queries, and scaling the application as needed.
4. Feedback Loop: Establish a feedback loop where performance insights and user feedback lead to further refinements and adjustments in the application.
5. Security Updates: Regularly update your application and server to patch any security vulnerabilities.

Conclusion

Migrating from Java EE to Jakarta EE can be a straightforward process if you follow the right steps and best practices. By understanding the key differences, updating your dependencies and code, thoroughly testing, and deploying your application to a Jakarta EE compatible server, you’ll be well on your way to leveraging the benefits of this powerful platform.

1. Jakarta EE Official Website
2. Jakarta EE API Documentation