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A cross-platform online judge system based on Spring MVC framework and ActiveMQ.


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Verwandlung Online Judge

Version: 0.2.0 (Released on August 30, 2018)

Build status Coverage Status Docker Automated build badgegen

Official Website | Tech Support | Change Log

Note: The continuous integration (CI) process is facing challenges as a result of bugs in the upstream activemq-broker.

Update: Verwandlung Online Judge now supports Docker. You can use Verwandlung Online Judge with ONLY 4 bash commands.

docker pull zjhzxhz/voj.web
docker pull zjhzxhz/voj.judger
docker run -d --name voj.web -p 8080:8080 zjhzxhz/voj.web
docker run -d --name voj.judger --link voj.web zjhzxhz/voj.judger

Tell me more about voj@Docker.


It is a cross-platform online judge system based on Spring MVC Framework.

The application used following open-source projects:

The Origin of Verwandlung

In 2011, LinkedIn Inc. launched a message queue called Kafka, which is written in Scala and available as open-source software.

A year later, Alibaba Inc. introduced a message queue named MetaQ which is built on top of Kafka and implemented in Java. The name "MetaQ" is derived from the title of a renowned literary work, "Metamorphosis", authored by Franz Kafka.

Since message queues are vital components in an application, the name of the application was chosen as "Verwandlung", which is the German translation for "Metamorphosis".


The Verwandlung application consists of two primary components:

  • Web Application
  • Judger (compatible with both Windows and Linux operating systems)

The overall architecture of the application can be illustrated by the diagram provided below:


As depicted in the diagram, the Verwandlung Online Judge features support for multiple judgers. These judgers are responsible for communicating with the web application through the use of ActiveMQ.

Getting Started

System Requirements

Hardware Requirements

  • CPU: 2.0 GHz or faster 32-bit (x86) or 64-bit (x64) processor

For Web Application (including Database and Message Queue):

  • RAM: 2.0 GB RAM on Windows, 1.0 GB RAM on Linux.

For Judger:

  • RAM: 1.0 GB RAM on Windows, 512 MB RAM on Linux.

Software Requirements

For Web Application (including Database and Message Queue):

For Judger:


Docker Releases (Recommended)

Now you can easily use Verwandlung Online Judge with Docker.

See the installation instructions here.

Binary Releases

  • Web Application: 0.2.0
  • Judger (Windows, 64 Bit): 0.2.0
  • Judger (Linux, 64 Bit): 0.2.0

Source Releases


  • Maven 3+ and GCC 4.8+ with POSIX thread model is required.
  • Make sure mvn (Maven), g++ and make are added to the PATH.

After download source code from this repository, run following commands from a terminal:

For Web Application:

cd web
mvn package -DskipTests

If the build is successful, the terminal will display a message as following:

[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 10.168 s
[INFO] Finished at: 2015-11-26T13:20:09+08:00
[INFO] Final Memory: 24M/210M
[INFO] ------------------------------------------------------------------------

And you'll get a package named voj.web.war in the target folder.

For Judger:


cd %JAVA_HOME%\include\win32
copy jawt_md.h  ..
copy jni_md.h  ..

cd judger
mvn package -DskipTests


cd $JAVA_HOME/include/linux
cp jawt_md.h jni_md.h ..

mvn package -DskipTests

If the build is successful, the terminal will display a message as following:

[INFO] Executing tasks

     [echo] Generating JNI headers
     [exec] mkdir -p target/cpp
     [exec] g++ -c -std=c++11 -Wall -fPIC -I ... -o target/cpp/Judger.Core.Runner.o
[INFO] Executed tasks
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 12.432 s
[INFO] Finished at: 2015-11-26T13:22:46+08:00
[INFO] Final Memory: 81M/513M
[INFO] ------------------------------------------------------------------------

And you'll get a package named voj.judger.jar in the target folder.


Setup the ActiveMQ

To reduce the memory of ActiveMQ, you can edit activemq.xml in ACTIVEMQ_HOME\conf.

Please find following content in this file, and change it to proper values that suitable for your servers.

            <!-- Change this value -->
            <memoryUsage limit="128 mb" />
            <!-- Change this value -->
            <storeUsage limit="4 gb"/>
            <!-- Change this value -->
            <tempUsage limit="4 gb"/>

Setup the Web Application

Create a database in MySQL, import voj.sql.

Edit the values in /WEB-INF/classes/ of the file voj.web.war.

You can open it with archive manager software such as WinRAR.

After then, you can copy this file voj.web.war to TOMCAT_HOME/webapps.

IMPORTANT: For Windows users, please edit server.xml of your Tomcat configuration:

<Connector connectionTimeout="20000" port="8080" protocol="HTTP/1.1"
    redirectPort="8443" useBodyEncodingForURI="true">

Setup the Judger

Edit the values in / of the file voj.judger.jar.

You can run the judger using following command :


javaw -jar voj.judger.jar


sudo java -jar voj.judger.jar


If you are using Linux, please run following commands using root:

# Shutdown and Kill process is not allowed for non-root user
chmod 700 /sbin/init
chmod 700 /sbin/poweroff
chmod 700 /usr/bin/pkill


We're glad that you want to improve this project.

  • We NEED TRANSLATORS for multi-language support(English and Chinese have supported).
  • You can report bugs here.
  • You can also create a pull request if you can fix the bug.
  • If you want to add features to the project, please tell us in the issues page before developing.

Thanks for your corporation.


This project is open sourced under GNU GPL v3.