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README.md

This is a directory containing a few java projects. The goal is to figure out how to use the platform to improve java UX.

Findings:

  • javax.annotations was removed between java 7 and 11

  • pure-java-rest-api has two jackson dependencies that allow for dependency hell

  • gradle not handled in this project

  • mvn will download each dependency and keep a cached copy under ~/.m2/repository

    • deleting that directory will force maven to re-download everything
    • even the simplest project (pure-java-rest-api) downloads hundreds of dependency jars
    • so publishing one ingredient for each might be untenable

  • spring boot projects have thousands of dependencies

Which projects?

Which java?

$ which java
/path/to/THR/third_party/bin/java

$ java --version
openjdk 11.0.15 2022-04-19 LTS
OpenJDK Runtime Environment Zulu11.56+19-CA (build 11.0.15+10-LTS)
OpenJDK 64-Bit Server VM Zulu11.56+19-CA (build 11.0.15+10-LTS, mixed mode)

Which mvn?

$ path/to/java/apache-maven-3.9.6/bin/mvn -v
Apache Maven 3.9.6 (bc0240f3c744dd6b6ec2920b3cd08dcc295161ae)
Maven home: /home/antoines/java/apache-maven-3.9.6
Java version: 11.0.15, vendor: Azul Systems, Inc., runtime: /home/antoines/.cache/asbazel/output/external/remotejdk11_linux
Default locale: en, platform encoding: UTF-8
OS name: "linux", version: "5.15.133.1-microsoft-standard-wsl2", arch: "amd64", family: "unix"

mvn exec (pure-java-rest-api)

I added the maven-exec-plugin so that I could run the pure-java-rest-api project, and validate that everything is on the classpath. From the pure-java-rest-api folder:

$ ../apache-maven-3.9.6/bin/mvn compile
[INFO] Scanning for projects...
[INFO]
[INFO] ------------< com.consulner.httpserver:pure-java-rest-api >-------------
[INFO] Building pure-java-rest-api 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- resources:3.3.1:resources (default-resources) @ pure-java-rest-api ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory /home/antoines/java/pure-java-rest-api/src/main/resources
[INFO]
[INFO] --- compiler:3.11.0:compile (default-compile) @ pure-java-rest-api ---
[INFO] Nothing to compile - all classes are up to date
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.519 s
[INFO] Finished at: 2024-02-20T13:40:08-05:00
[INFO] ------------------------------------------------------------------------

The first time you run the above it will produce tons of download output. Then run the compiled server by doing:

$ ../apache-maven-3.9.6/bin/mvn exec:java
[INFO] Scanning for projects...
[INFO]
[INFO] ------------< com.consulner.httpserver:pure-java-rest-api >-------------
[INFO] Building pure-java-rest-api 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- exec:1.4.0:java (default-cli) @ pure-java-rest-api ---
Hello World!

The final Hello World! was added by me as the first line in Application.java (to ensure that I am indeed compiling the right thing). You can call the rest API by doing a GET on localhost:8000/api/hello, passing admin/admin in a basic authentication (otherwise it returns a 401).

Notes

  1. You cannot mvn exec:java if it's not already compiled. There is a way make maven automatically compile before exec:java, but that involves further modifying the pom.xml.
  2. You can do mvn clean to delete the target folder (where compiled things go)
  3. You can do mvn clean compile to force a complete rebuild (it's like doing mvn clean followed by mvn compile)

Dependency hell

In pom.xml, replacing jackson-annotations's version from 2.9.7 to 2.0.0 will still compile (maven doesn't solve dependencies), but produce a runtime error:

Hello World!
[WARNING]
java.lang.reflect.InvocationTargetException
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:293)
    at java.lang.Thread.run (Thread.java:829)
Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/annotation/JsonMerge
    at com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector.<clinit> (JacksonAnnotationIntrospector.java:50)
    at com.fasterxml.jackson.databind.ObjectMapper.<clinit> (ObjectMapper.java:291)
    at com.consulner.app.Configuration.<clinit> (Configuration.java:11)
    at com.consulner.app.Application.main (Application.java:27)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:293)
    at java.lang.Thread.run (Thread.java:829)
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.annotation.JsonMerge
    at java.net.URLClassLoader.findClass (URLClassLoader.java:476)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:589)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:522)
    at com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector.<clinit> (JacksonAnnotationIntrospector.java:50)
    at com.fasterxml.jackson.databind.ObjectMapper.<clinit> (ObjectMapper.java:291)
    at com.consulner.app.Configuration.<clinit> (Configuration.java:11)
    at com.consulner.app.Application.main (Application.java:27)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:293)
    at java.lang.Thread.run (Thread.java:829)

Compile failure (FizzBuzzEnterpriseEdition)

From the FizzBuzzEnterpriseEdition folder, run:

$ ../apache-maven-3.9.6/bin/mvn compile
[INFO] Scanning for projects...
[INFO]
[INFO] --< com.seriouscompany.business.java.fizzbuzz:FizzBuzzEnterpriseEdition >--
[INFO] Building FizzBuzz Enterprise Edition 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- jacoco:0.5.8.201207111220:prepare-agent (default) @ FizzBuzzEnterpriseEdition ---
[INFO] argLine set to -javaagent:/home/antoines/.m2/repository/org/jacoco/org.jacoco.agent/0.5.8.201207111220/org.jacoco.agent-0.5.8.201207111220-runtime.jar=destfile=/home/antoines/java/FizzBuzzEnterpriseEdition/target/jacoco.exec
[INFO]
[INFO] --- resources:3.3.1:resources (default-resources) @ FizzBuzzEnterpriseEdition ---
[INFO] Copying 1 resource from resources/assets/configuration/spring/dependencyinjection/configuration to target/classes
[INFO]
[INFO] --- compiler:2.3:compile (default-compile) @ FizzBuzzEnterpriseEdition ---
[INFO] Compiling 87 source files to /home/antoines/java/FizzBuzzEnterpriseEdition/target/classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] /home/antoines/java/FizzBuzzEnterpriseEdition/src/main/java/com/seriouscompany/business/java/fizzbuzz/packagenamingpackage/impl/math/arithmetics/NumberIsMultipleOfAnotherNumberVerifier.java:[4,23] error: package javax.annotation does not exist

[ERROR] /home/antoines/java/FizzBuzzEnterpriseEdition/src/main/java/com/seriouscompany/business/java/fizzbuzz/packagenamingpackage/impl/math/arithmetics/NumberIsMultipleOfAnotherNumberVerifier.java:[26,2] error: cannot find symbol

[INFO] 2 errors
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.458 s
[INFO] Finished at: 2024-02-20T13:47:30-05:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.3:compile (default-compile) on project FizzBuzzEnterpriseEdition: Compilation failure: Compilation failure:
[ERROR] /home/antoines/java/FizzBuzzEnterpriseEdition/src/main/java/com/seriouscompany/business/java/fizzbuzz/packagenamingpackage/impl/math/arithmetics/NumberIsMultipleOfAnotherNumberVerifier.java:[4,23] error: package javax.annotation does not exist
[ERROR]
[ERROR] /home/antoines/java/FizzBuzzEnterpriseEdition/src/main/java/com/seriouscompany/business/java/fizzbuzz/packagenamingpackage/impl/math/arithmetics/NumberIsMultipleOfAnotherNumberVerifier.java:[26,2] error: cannot find symbol
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException

Q: Both of these errors are related to the fact that javax.annotations is not found. Could this be because we're using openJDK 11, and the project expects java 11? A: javax.annotations was REMOVED in java 11. It needs to be added manually to the project

  • Maven Central
  • After adding it explicitely to the pom.xml dependencies, the project compiles successfully

Compile failure (spring-boot-examples/spring-boot-2-rest-service-basic)

From the spring-boot-examples/spring-boot-2-rest-service-basic folder, run:

$ ../../apache-maven-3.9.6/bin/mvn compile
[INFO] Scanning for projects...
[INFO]
[INFO] --< com.in28minutes.springboot.rest.example:spring-boot-2-rest-service-basic >--
[INFO] Building spring-boot-2-rest-service 0.0.1-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- resources:3.3.0:resources (default-resources) @ spring-boot-2-rest-service-basic ---
[INFO] Copying 1 resource
[INFO] Copying 2 resources
[INFO]
[INFO] --- compiler:3.10.1:compile (default-compile) @ spring-boot-2-rest-service-basic ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 5 source files to /home/antoines/java/spring-boot-examples/spring-boot-2-rest-service-basic/target/classes
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.006 s
[INFO] Finished at: 2024-02-20T14:29:15-05:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.10.1:compile (default-compile) on project spring-boot-2-rest-service-basic: Fatal error compiling: error: invalid target release: 17 -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

This failure is because mvn uses java 11, but the project to be compiled requires java 17. From the pom.xml:

    <properties>
        <java.version>17</java.version>
    </properties>

output to mvn -v:

Java version: 11.0.15, vendor: Azul Systems, Inc., runtime: /home/antoines/.cache/asbazel/output/external/remotejdk11_linux

I don't really want to mess with java versions on my machine for this, but something to try would be to:

  1. Install java 17, ensure that mvn sees it (as per mvn -v)
  2. Re-compile the spring boot example project, and see if it resolves the issue

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