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Build and Run the Helidon Virtual thread and Reactive application

Introduction

This lab walks you through the process of building and running the Helidon 4 and Helidon 3 Reactive applications in Oracle Code Editor inside Oracle Cloud Infrastructure.

Lab2 walkthrough

Estimated Time: 15 minutes

Objectives

In this lab, you will:

  • Build, run and test the Helidon 4 Virtual thread application
  • Build, run and test the Helidon 3 Reactive application
  • Analyse the simplicity of the Virtual thread application comparative to Reactive application

Prerequisites

To run this lab, you must have:

  • Oracle Cloud Account
  • Completed Lab 1, which install the required JDK and maven.

Task 1: Build and Run the Helidon 4 application

  1. Click File -> Open in Code Editor. Open Project

  2. Select helidon-virtual-thread folder and click Open. Helidon Project

    Please ignore the warnings/problems, you notice in Code Editor while opening this folder.

  3. Open a new terminal, and then copy and paste the following command to set the PATH and JAVA_HOME variable.

    <copy>PATH=~/jdk-21.0.2/bin:~/apache-maven-3.8.3/bin:$PATH
JAVA_HOME=~/jdk-21.0.2/</copy>

  4. Copy the following command and run in the terminal to verify that required JDK and Maven version are configured properly.

    <copy>mvn -v</copy>

    you will have the output similar to the following:

    $ mvn -v
Apache Maven 3.8.3 (ff8e977a158738155dc465c6a97ffaf31982d739)
Maven home: /home/ankit_x_pa/apache-maven-3.8.3
Java version: 21.0.2, vendor: Oracle Corporation, runtime: /home/ankit_x_pa/jdk-21.0.2
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "4.14.35-2047.529.3.2.el7uek.x86_64", arch: "amd64", family: "unix"
$

    You will use only this terminal for building and running the application as it has the required JDK and Maven version.

  5. Copy and paste the following command to build the blocking application.

    <copy>cd ~/helidon-virtual-thread/virtualthread/
mvn clean package -DskipTests</copy>

    You will have output similar to the following:

    [INFO] --- maven-jar-plugin:3.0.2:jar (default-jar) @ example-virtual-thread ---
[INFO] Building jar: /home/ankit_x_pa/helidon-virtual-thread/virtualthread/target/example-virtual-thread.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  3.258 s
[INFO] Finished at: 2024-02-21T08:20:52Z
[INFO] ------------------------------------------------------------------------
$

  6. Copy and paste the following command in the terminal to run the blocking version of the application:

    <copy>java -jar target/example-virtual-thread.jar</copy>

    You will have output similar to the following:

    $ java -jar target/example-virtual-thread.jar
Feb 21, 2024 8:22:10 AM io.helidon.config.MetaConfigFinder lambda$findSource$9
WARNING: Configuration file application.yaml is on classpath, yet there is no parser configured for it
Feb 21, 2024 8:22:10 AM io.helidon.webserver.ServerListener start
INFO: [0x20695538] http://0.0.0.0:38197 bound for socket '@default'
Feb 21, 2024 8:22:10 AM io.helidon.common.features.HelidonFeatures features
INFO: Helidon SE 4.0.5 features: [Config, Encoding, Media, WebClient, WebServer]
Feb 21, 2024 8:22:10 AM io.helidon.webserver.LoomServer startIt
INFO: Started all channels in 41 milliseconds. 645 milliseconds since JVM startup. Java 21.0.2+13-LTS-58

  7. Write down the port number on which the server runs (see the log entry for @default). For example, in our output, the port number is 38197. Similarly, find out your server port number.

  8. To open new terminal, click Terminal -> New Terminal. We will use this terminal to run curl commands. New Terminal

  9. Copy and paste the following command into the new terminal. Don't forget to replace <port> with your server port.

    <copy>curl http://localhost:<port>/one</copy>

    You will have output similar to the following:

    curl http://localhost:38197/one
remote_1
$

  10. Copy and paste the following command into the new terminal. Don't forget to replace to <port> with your server port.

    <copy>curl http://localhost:<port>/sequence</copy>

    You will have output similar to the following:

    $ curl http://localhost:38197/sequence
Combined results: [remote_2, remote_3, remote_4, remote_5, remote_6, remote_7, remote_8, remote_9, remote_10, remote_11]
$

    Notice the order of the results. As suggested by the name, this request invokes a remote resource multiple times in sequence.

  11. Copy and paste the following command into the new terminal. Don't forget to replace to <port> with your server port.

    <copy>curl http://localhost:<port>/parallel</copy>

    You will have output similar to the following:

    $ curl http://localhost:38197/parallel
Combined results: [remote_21, remote_18, remote_12, remote_13, remote_14, remote_15, remote_16, remote_17, remote_19, remote_20]
$

    Notice the order of the results. As suggested by the name, this request invokes a remote resource multiple times in parallel.

  12. Press the Ctrl + C in the terminal where *java -jar * command is running to to stop the server.

Task 2: Build and Run the Reactive application

  1. Copy and paste the following command to build the reactive application.

    <copy>cd ~/helidon-virtual-thread/reactive/
mvn clean package -DskipTests</copy>

    You will have output similar to the following:

    [INFO] --- maven-dependency-plugin:3.0.0:copy-dependencies (copy-libs) @ example-reactive ---
[INFO] 
[INFO] --- maven-jar-plugin:3.0.2:jar (default-jar) @ example-reactive ---
[INFO] Building jar: /home/ankit_x_pa/helidon-virtual-thread/reactive/target/example-reactive.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  3.023 s
[INFO] Finished at: 2024-02-21T08:25:36Z
[INFO] ------------------------------------------------------------------------
$

  2. Copy and paste the following command in the terminal to run the reactive version of the application:

    <copy>java -jar target/example-reactive.jar</copy>

    You will have output similar to the following:

    $ java -jar target/example-reactive.jar
2024.02.21 08:30:28.921 Logging at initialization configured using classpath: /logging.properties
2024.02.21 08:30:29.191 Configuration file application.yaml is on classpath, yet there is no parser configured for it
2024.02.21 08:30:29.449 Helidon SE 3.2.5 features: [Config, Fault Tolerance, Tracing, WebServer]
2024.02.21 08:30:29.601 Channel '@default' started: [id: 0x3ab38b5d, L:/0.0.0.0:33547]

  3. Write down the port number on which the server runs (see the log entry for @default). For example, in our output, the port number is 33547. Similarly, find out your server port number.

  4. Go back to the terminal, which we opened in Task 1 for running the curl command.

  5. Copy and paste the following command into the new terminal. Don't forget to replace to <port> with your server port.

    <copy>curl http://localhost:<port>/one</copy>

    You will have output similar to the following:

    $ curl http://localhost:33547/one
remote_1
$

  6. Copy and paste the following command into the new terminal. Don't forget to replace to <port> with your server port.

    <copy>curl http://localhost:<port>/sequence</copy>

    You will have output similar to the following:

    $ curl http://localhost:33547/sequence
Combined results: [remote_2, remote_3, remote_4, remote_5, remote_6, remote_7, remote_8, remote_9, remote_10, remote_11]
$

    Notice the order of the results. As suggested by the name, this request invokes a remote resource multiple times in sequence.

  7. Copy and paste the following command into the new terminal. Don't forget to replace to <port> with your server port.

    <copy>curl http://localhost:<port>/parallel</copy>

    You will have output similar to the following:

    $ curl http://localhost:33547/parallel
Combined results: [remote_17, remote_16, remote_13, remote_20, remote_12, remote_19, remote_18, remote_14, remote_21, remote_15]
$

    Notice the order of the results. As suggested by the name, this request invokes a remote resource multiple times in parallel.

  8. Press the Ctrl + C in the terminal where *java -jar * command is running to to stop the server.

Task 3: Analyse the simplicity of the Helidon 4 application

Virtual thread vs. Reactive

Let’s compare the implementations between Virtual thread and Helidon SE (reactive) for the same task.

  • Both implementations execute REST calls using the Helidon WebClient
  • The Virtual thread implementation is straightforward to follow:
    • The execution flow is reflected by the statement order in the code
    • There are no calls to intricate or semantically-rich library calls
    • Debugging is straightforward
  • Reactive versions require a good understanding of reactive libraries
    • Including Multi, flatMap, error handling, etc.
    • Control flow is no longer obvious due to use of reactive handlers
    • An understanding of flatMap's capability to enable/forbid concurrency is required
    • Debugging is more difficult

  1. Open the virtualthread/src/main/java/io/examples/helidon/virtualthread/BlockingService.java file to see how endpoints are implemented in the blocking version of the application. Blocking Block

  2. Open the reactive/src/main/java/io/examples/helidon/reactive/ReactiveService.java file to see how endpoints are implemented in the reactive version of the application. Reactive Service

  3. In OPEN EDITORS section, right click on the BlockingService.java file and select the Select for Compare. Select Compare

  4. Right click on the ReactiveService.java file and select the Compare with Selected. Compare selected

  5. See that reactive code is more complicated than blocking (Virtual Thread) Compare code

    Check methods one, sequence and parallel in BlockingService and ReactiveService respectively. See if you understand how they work!

You may now proceed to the next lab.

Acknowledgements

  • Author - Ankit Pandey
  • Contributors - Sid Joshi, Maciej Gruszka
  • Last Updated By/Date - Ankit Pandey, March 2025