Messaging with Apache Artemis

Prepare your environment

• Java classes, loops, exceptions and basic Maven usage. No messaging experience required.
• A supplied JDK 21 and four separate cmd.exe terminals on Windows, or shells on Linux/macOS.
• An invitation to the private training repository for editable source, or the trainer’s verified runtime ZIP for demonstrations.
• Your own local broker. Docker, administrator rights and a remote broker are not required.

The trainer can distribute a verified runtime ZIP and JDK 21 before the session. Extract both and follow RUN.md; local demonstrations need no Maven or network. Editing exercises needs the full source and a build environment. An offline source build additionally requires a prepared Maven Wrapper distribution and dependency/plugin cache. A runtime ZIP alone cannot compile exercises.

Repository access does not follow from visiting these public pages. Invited collaborators can see the sample solutions and other branches. On GitHub, download an artifact from a successful Actions run for the agreed revision, extract its runtime ZIP, and read RUN.md. Private artifacts expire after seven days; your trainer should prepare them before the session.

English reference revision: 71fc36e. Verified Windows/Linux run and private artifacts. Private source and complete worked solutions require repository access.

How you will learn

Predict → Run → Break → Explain → Adapt

Work on your own local broker first. With a partner, alternate driver and navigator every 15–20 minutes: one operates, the other predicts and reconciles IDs. Each person demonstrates one changed condition.

Make your initial prediction before revealing hints or asking AI. AI assistance is optional and subject to company policy. Verify suggestions against your code and logs; do not provide credentials, confidential code or company data. You never need to upload prompts or chat histories.

Use the worksheet or local notes for predictions and evidence. These pages do not execute commands or collect your answers. The checklist is your own self-assessment.

Set up once, in separate terminals

Windows commands are selected initially. Lab root: the folder containing mvnw.cmd (source) or RUN.md (runtime ZIP). Check java -version and javac -version; both should use your supplied JDK 21. Set JAVA_HOME to its root directory if needed. Configure company proxies/certificates through approved IT settings.

git clone https://github.com/grobmeier/artemis-java-jumpstart.git
cd artemis-java-jumpstart
git switch -c feature/YOUR_GITHUB_NAME-labs 71fc36ed1f39422a058d35598922599e2004cf0e
.\mvnw.cmd -Ptraining clean verify

.\scripts\broker.cmd start

.\scripts\doctor.cmd runtime

Choose the right entry point: lab runs finished demonstrations; exercises runs your editable implementations; solutions runs separate worked examples. Build source changes again with the training profile. Do not mix their messages in an old namespace.

No Docker, admin rights, PowerShell policy change or external broker is required. The optional central-broker profile is follow-up material and needs a separate company-network preflight.

Your learning path

1. Station 1 · 45 minutes

   Queues and competing consumers

   Explain how a queue retains waiting work and how consumers share it.

   Start station →
2. Station 2 · 45 minutes

   Events and independent subscribers

   Distinguish shared work from independent interest in the same event.

   Start station →
3. Station 3 · 60 minutes

   Acknowledgement, retry and dead letters

   Explain what is confirmed, what can be delivered again, and how failed work is recovered deliberately.

   Start station →

Debrief and finish

Show a partner or trainer one changed condition. Explain where work waited, who received a copy, and what was confirmed before failure. Support your explanation with business IDs and queue state.

Stop all workers with Ctrl+C. Ask the local broker to stop and wait for its process to exit. A full reset is optional and deletes your owned broker messages; use it only for an exclusively owned local lab after every client and the broker have stopped. Ownership-marker, path and process-lock guards must remain intact. The H2 ledger is separate. Never reset a shared remote broker for an individual exercise.

.\scripts\broker.cmd stop

.\scripts\broker.cmd reset --confirm

Optional next steps in the private repository: S04 durable subscriptions; S09 idempotency for one local DB effect; selectors and other scenarios. A first pilot with two trainees will help refine timing and clarity.