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High-performance dynamic image server in Java
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🍈 Cantaloupe

High-performance dynamic image server in Java


Get started with a release build.


Build & run

Command line

  • mvn exec:java -Dcantaloupe.config=... will build the project and run in standalone mode, using the embedded Servlet container listening on the port(s) specified in
  • mvn clean package -DskipTests will build a release WAR in the target folder, which can be run like any other.


There are a few ways to do this. The simplest is probably:

  1. Add a new run configuration using the "Java Application" template or its equivalent.

  2. Set the main class to edu.illinois.library.cantaloupe.StandaloneEntry and add the -Dcantaloupe.config=... VM option.

  3. Set the run configuration to include dependencies with provided scope. (IntelliJ has a checkbox for this.) Alternatively, download servlet-api-3.1.jar and add it to your classpath: --class-path=/path/to/servlet-api-3.1.jar

    Or, in Java 9+, your module path: --module-path=/path/to/containing/dir


Testing the code

Copy to and fill in whatever info you have.

The code tests are structured into three Maven profiles:

1. Tests with no dependencies

mvn clean test -Pnodeps will run only the tests that have no dependencies on third-party services and do not require any external tools or libraries.

2. Tests with free dependencies

mvn clean test -Pfreedeps will run all of the above tests, plus any that depend on open-source tools or libraries. These are the tests run in continuous integration. The following dependencies are required:

  • DynamoDB or dynamodb-local (for DynamoDBCacheTest)
  • FFmpeg (for FfmpegProcessorTest)
  • OpenJPEG (for OpenJpegProcessorTest)
  • Redis (for RedisCacheTest)
  • TurboJPEG with Java binding (for TurboJpegProcessorTest)

3. All tests

mvn clean test will run all tests, including the ones above. The following dependencies are required in addition to the ones above:

  • Kakadu native library (for KakaduNativeProcessorTest) - see the KakaduNativeProcessor section of the user manual for information.
  • A Microsoft Azure account


Because it can be a chore to install all of the dependencies needed to get all of the tests in the freedeps profile passing, there is a Docker testing image available that contains all needed dependencies. See the /.travis.yml file.

Output testing

There is an output tester tool that enables visual inspection of image output.

Performance testing

Performance tests use JMH. Run them with mvn clean test -Pbenchmark.


Contributions are welcome. The suggested process for contributing code changes is:

  1. Submit a "heads-up" issue in the tracker, ideally before beginning any work.
  2. Create a fork.
  3. Create a feature branch, starting from either release/x.x or develop (see the "Versioning" section.)
  4. Make your changes.
  5. Commit your changes (git commit -am 'Add some feature').
  6. Push the branch (git push origin feature/my-new-feature).
  7. Create a pull request.

Other Notes

Configuration keys

Different application versions may require different configuration file keys. It's good practice to use a dedicated configuration file for each version. Key changes are documented in


Cantaloupe roughly uses semantic versioning. Major releases (n) involve major rearchitecting that breaks backwards compatibility in a significant way. Minor releases (n.n) either do not break compatibility, or only in a minor way. Patch releases (n.n.n) are for bugfixes only.


Cantaloupe uses the Gitflow branching model. develop is the main branch that tracks the current state of the next non-bugfix release. Significant features branch off of that into feature branches (feature/feature-name), from which they can be integrated into a particular release.

When a major or minor version is ready for release in develop, it branches off into a release/n.n branch, where its version is set. Finally, that is merged into master, where the release is tagged and the release archive is created.

Bugfixes that would increment a minor version of a release are applied to the release branch for that release, and merged back into develop.


  1. Run the Maven Verifier plugin (mvn verify -DskipTests=true)
  2. Run an OWASP dependency check (mvn org.owasp:dependency-check-maven:check)
  3. Run Findbugs (mvn clean compile findbugs:findbugs findbugs:gui)
  4. Run the tests:
  5. Finalize the code to be released, addressing any relevant milestone issues, TODOs, etc.
  6. Finalize the documentation, including the website, user manual, and change log


  1. Merge into release/vX.X
  2. Update the version in pom.xml and commit this change
  3. Merge into master
  4. Push the code: git push origin master; git push origin release/x.x
  5. Wait for CI tests to pass
  6. Create the release .zip archive with mvn clean package -DskipTests
  7. Verify that the .zip archive is as expected
  8. Tag the release: git tag -a v{version} -m 'Tag v{version}'
  9. git push --tags
  10. Add the .zip archive and change log info to the release tag on GitHub
  11. Deploy the updated website (usually not necessary for bugfix releases)
  12. Close the release's GitHub milestone


Cantaloupe is open-source software distributed under the University of Illinois/NCSA Open Source License; see the file LICENSE.txt for terms.

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