Rex is an easy-to-use Shiny dashboard for creating, managing, and evaluating written exams using R/exams. It is designed to simplify workflows for educators while supporting complex, randomized exercise formats and fully automated evaluation.
Rex is developed by Sebastian Bachler.
A hosted version with example files is available on request via email.
Ensure the following system dependencies are available:
libsodium-devlibmagick++-devlibpoppler-cpp-devghostscripttexlive-fullpandoc
Install required R packages as listed in app.R and worker.R.
Then launch the app via:
shiny::runApp(appDir = '<base directory containing app.R>', host = '0.0.0.0', port = 3838)Alternatively, open and run app.R in RStudio.
Ensure the database file is owned by UID=1001 and GID=1001:
chown 1001:1001 /home/rex.sqlite
chmod 660 /home/rex.sqliteBuild and run using:
docker-compose -f compose_rex.yaml up --buildCAUTION
Rex uses a hardened Docker setup:
- Non-root users with dropped capabilities
- Background worker has no network access
- Resource-limited containers
Always audit third-party dependencies before deployment.
Use at your own risk and follow security best practices.
Rex supports:
- Basic login (default user:
rex, password:rex) - Single Sign-On (SSO) integration for OAuth 2.0 (configurable for institutional environments)
✅ Browser recommendation: Firefox
Use the “EXERCISES” tab to manage exercises.
Rex supports two types of exercises:
These are created directly within the app using the UI. Ideal for users without programming experience.
- Fully editable in the app
- Supports inline math and full LaTeX environments
- Fields include:
- Name, Author, Type, Points, Section
- Question text and solution note
- Answer options with true/false flags and notes
- One PNG figure per exercise
- Toggle LaTeX environments
- Can be exported to
.RMDor.RNWformat and later re-imported without losing editability
These are authored externally in .RMD or .RNW files using R features such as:
- Dynamic code chunks (e.g. random number generation)
- Custom LaTeX environments
- Arbitrary R logic for exercise generation
These exercises can be imported into Rex, but cannot be edited directly in the UI.
⚠️ You may optionally convert advanced exercises to simple ones for editing, but this can lead to loss of functionality or formatting.
Go to “EXAM” > “Create exam” to generate an exam.
Steps:
- Ensure exercises are marked as examinable.
- Configure options and click “Create exam”.
- Download the generated ZIP archive, which includes:
- PDF files of all exam versions — intended for printing and distribution to students
- HTML files matching the PDF versions — include solutions and are meant for quality control before the exam
- RDS file for later evaluation
- All exercises used in the exam
input.txt— contains all parameter values used for exam creationcode.txt— R code to reproduce the exam outside of Rex
Navigate to “EXAM” > “Evaluate exam”.
Required files:
- Solutions: RDS file from exam creation
- Participants: CSV (optional; dummy users will be used if omitted)
- Scans: PDF or PNG of evaluation sheets (same orientation recommended)
After evaluation:
- Manual review/editing of scans is possible
- Output ZIP includes:
- Converted scans (
*_nops_scan.zip) - Individual evaluation reports (
*_nops_eval.zip) - Overall evaluation CSV
- PDF report and raw statistics
input.txtandcode.txt
- Converted scans (
Extend Rex with custom features like:
- Default values
- Additional UI fields
- Entirely new logic modules
CAUTION
Addons may increase attack surface.
Use at your own risk.
Pull requests welcome! For larger changes, open an issue to discuss first.
- Accessibility: UI tailored for users with no programming experience (DE & EN)
- Authentication: Single Sign-On (SSO) support for OAuth 2.0
- Secure: Dockerized with minimized privileges
- Exercise Format: Supports both
.RMDand.RNW - Flexibility: Full compatibility for more advanced (coded) exercises
