Catnip

Catnip is a next step recommendation generation tool for Scratch projects.

Catnip is developed at the Chair of Software Engineering II and the Didactics of Informatics of the University of Passau.

This branch contains the version of Catnip as presented at ITiCSE 2022. For our ITiCSE 2021 paper (c.f. Publications), see the branch previous_version.

Checkout with git clone --recursive to clone the scratch-gui and whisker submodules.

Running The Hint Generator

Using docker-compose

• In build_containers.sh change the path to a Java 11 JDK.
• Run build_containers.sh to
  • apply the necessary patches to Whisker and the Scratch GUI
  • Build the Docker containers for the GUI and the backend modules.
• Add some solution sb3-programs to the run_conf/tasks/.../solutions/ folder.
• Adapt the settings in run_conf/application.conf.
• docker-compose up to start the containers.
• The GUI can be reached on http://localhost:8080/.
• Ctrl + C stops the containers, they can then be removed with docker-compose down.

With Whisker

• In run_conf/application.conf enable the option runTestSuite.
• In docker_compose.yml uncomment/adapt the paths to the Whisker tests file and the Whisker folder.

Without Docker

Server

• Run ./sbtx -java-home $JDK11 serve/assembly where $JDK11 is the path to some Java 11 JDK.
• The runnable JAR file is placed in serve/target/scala-2.13/hintgen-serve.jar. Copy it into run_conf.
• Adapt the settings in run_conf/application.conf.
  • Especially the settings receivedProgramsDir, tasksBasePath, and tasks have to be adapted.
  • You can ignore the whisker… settings if runTestSuite is false.
• Start the server with shell cd run_conf $JDK11/bin/java -Dconfig.file=application.conf -Dplay.http.secret.key="…" -jar hintgen-serve.jar

GUI

• Adapt the URL to the server component in run_conf/server-info.txt.
• Run the same commands as in the GUI-section of build_containers.sh.
  • Instead of running the docker command, place the content of the scratch_gui/build directory into a folder that is served by some HTTP server like nginx or Apache2.

Project Structure

• algorithm: the actual implementation of the hint generator.
• serve: the backend server connecting the GUI to the algorithm.
• run_conf: configuration files for the server components.
• example_programs: sb3 files used for unit-testing the various components.
• scratch-gui, whisker: git submodules containing the respective projects.
• program_fixer.py: The comments added by the hint generator to the programs sometimes cannot be removed properly when copying blocks during application of the hints. This results in an invalid program that neither LitterBox nor the scratch-vm itself can parse.

This program removes all comments from a program to make it usable again. Takes the filename of the program as first argument.

Publications

To learn more about Catnip and its hint generation technique, see the following papers:

• F. Obermüller, U. Heuer, and G. Fraser, “Guiding Next-Step Hint Generation Using Automated Tests”, in 26th ACM Conference on Innovation and Technology in Computer Science Education V. 1 (ITiCSE 2021), ACM, 2021. https://doi.org/10.1145/3430665.3456344
  • code available on branch previous_version
• B. Fein, F. Obermüller, and G. Fraser, “Catnip: An Automated Hint Generation Tool for Scratch”, in 27th ACM Conference on Innovation and Technology in Computer Science Education V. 1 (ITiCSE 2022), ACM, 2022. https://doi.org/10.1145/3502718.3524820
  • code available on branch master

Contributors

Benedikt Fein\ Gordon Fraser\ Florian Obermüller

Licence Information

• Packaged with the APTED algorithm (algorithm/lib/apted.jar), published under MIT licence. No source code has been changed.

Modules algorithm, common

Licenced under the EUPL, Version 1.2 or – as soon as they will be approved by the European Commission - subsequent versions of the EUPL (the ‘Licence’). You may not use this work except in compliance with the Licence. You may obtain a copy of the Licence at:

https://joinup.ec.europa.eu/software/page/eupl

Unless required by applicable law or agreed to in writing, software distributed under the Licence is distributed on an ‘AS IS’ basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either expressed or implied. See the Licence for the specific language governing permissions and limitations under the Licence.

Module serve

This module contains the class CustomScratchBlocksVisitor that is directly based on the source of the LitterBox class ScratchBlocksVisitor as it can be found in LitterBox version 1.5.

Therefore, this module is licensed GPL-3.0 identically to LitterBox. You may use, distribute and copy it under those licence terms.