cd5cc0cb5c
1. Replace the OpenJDK with an unmodified OpenJDK from Alpine Linux 2. Add Alibaba Dragonwell as the default JDK for the Java demos
53 lines
2.3 KiB
Markdown
53 lines
2.3 KiB
Markdown
# Use Java with Occlum
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This project demonstrates how Occlum enables _unmodified_ Java programs running in SGX enclaves.
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# About JDK
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Both the unmodified [OpenJDK 11](https://hg.openjdk.java.net/portola/jdk11), which is imported from Alpine Linux, and the [Alibaba Dragonwell](https://github.com/alibaba/dragonwell11/tree/dragonwell-for-enclave), which is a downstream version of OpenJDK, are supported now. We have already installed OpenJDK and Dragonwell while building the Docker image, the OpenJDK is installed at `/opt/occlum/toolchains/jvm/java-11-openjdk`, and the Dragonwell is installed at `/opt/occlum/toolchains/jvm/java-11-alibaba-dragonwell`.
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Our demos use Dragonwell as the default JDK, you are free to change to OpenJDK by setting the `JAVA_HOME` to point to the installation directory of OpenJDK and copying it into Occlum instance.
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## Demo: Hello World
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We provide a "Hello World" demo to show how to run a simple Java program inside SGX enclaves. The demo code can be found [here](hello_world/).
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### How to Run
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Step 1: Compile the source code with `occlum-javac`
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```
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occlum-javac ./hello_world/Main.java
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```
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When completed, the resulting file can be found at `./hello_world/Main.class`.
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Step 2: Start JVM to run the hello world program
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```
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./run_java_on_occlum.sh hello
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```
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## Demo: Web application with Spring Boot
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We also choose a Java web application that using WebSocket with [Spring Boot](https://spring.io/projects/spring-boot). The demo code can be found [here](https://github.com/spring-guides/gs-messaging-stomp-websocket).
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### How to Run
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Step 1: Download the demo code and build a Fat JAR file with Maven
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```
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./download_and_build_web_app.sh
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```
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When completed, the resulting Fat JAR file can be found at `./gs-messaging-stomp-websocket/complete/target/gs-messaging-stomp-websocket-0.1.0.jar`.
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Step 2: Start JVM to run the JAR file on Occlum
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```
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./run_java_on_occlum.sh web_app
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```
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The web application should now start to listen on port 8080 and serve requests.
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Step 3: To check whether it works, run
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```
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curl http://localhost:8080
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```
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in another terminal.
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It is recommended to access the web application in a Web browser. You have to manually map port 8080 of the Docker container to a port on the host OS. Check out how to use [the `-p` argument of `docker run` command](https://docs.docker.com/engine/reference/commandline/run/).
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