Java Digest Bot

Java Digest Bot tracks key Java ecosystem sources (RSS feeds, OpenJDK mailing lists, and JEP changes), then publishes AI-assisted daily summaries to Slack channels.

The project supports:

• Channel-based Slack routing (general, amber, valhalla, loom, leyden, panama)
• Per-link short AI summaries
• Detailed long-form channel summaries for Amber and Valhalla
• Retry/fallback behavior for Gemini API rate/load issues

What It Tracks

Author-filtered RSS feeds

Source	Method
inside.java	RSS + tracked author filter
InfoQ Java	RSS + tracked author filter

OpenJDK mailing lists

List	Focus area
amber-spec-experts	Records, Pattern Matching, Sealed Classes
valhalla-spec-observers	Value Types, Null Safety
loom-dev	Virtual Threads, Structured Concurrency
jdk-dev	General JDK development
panama-dev	Foreign Function & Memory API
leyden-dev	Startup performance, AOT
compiler-dev	Compiler/HotSpot
zgc-dev	ZGC

Community feeds

Source	Notes
dev.java	Official Java developer portal
Java Almanac	Java platform/version updates (GitHub Atom feed)
Foojay	Community updates and deep dives
Baeldung	Tutorials and practical guides
DZone Java	Java ecosystem articles
Spring Blog	Spring updates
Quarkus Blog	Quarkus updates
JetBrains IDEA Blog	Tooling updates

JEP status tracking

JEP changes are checked from openjdk.org/jeps/0 for: Amber, Valhalla, Loom, Panama, Leyden, Lilliput.

Slack Community and Channels

You can join the java-newsletter Slack community and subscribe only to channels you care about.
After joining the workspace, simply join channels like:

• #java-general
• #java-amber
• #java-valhalla
• #java-loom
• #java-leyden
• #java-panama
• #java-jep (version/JEP status updates and platform-level changes)

Then you can just wait for scheduled updates in that channel.

Example screenshots

Channel selection example:

General channel message example:

Valhalla channel message example:

Setup

1) Clone the repository

git clone https://github.com/umiitkose/java-newsletter
cd java-newsletter

2) Configure sources and filters

All source/filter settings are centralized in config.yml:

authors:
keywords:
rss:
mailingLists:
jep:
ai:
pages:

Current default AI config in the repository:

ai:
  enabled: true
  provider: gemini

3) Configure Slack webhooks

Create one incoming webhook per target channel in Slack.

Required minimum:

• SLACK_WEBHOOK_GENERAL

Optional project channels:

• SLACK_WEBHOOK_AMBER
• SLACK_WEBHOOK_VALHALLA
• SLACK_WEBHOOK_LOOM
• SLACK_WEBHOOK_LEYDEN
• SLACK_WEBHOOK_PANAMA
• SLACK_WEBHOOK_JEP

4) Configure GitHub Actions secrets / variables

Go to: Repository -> Settings -> Secrets and variables -> Actions

Recommended secrets:

Name	Required	Description
SLACK_WEBHOOK_GENERAL	Yes	General channel webhook
SLACK_WEBHOOK_AMBER	No	Amber channel webhook
SLACK_WEBHOOK_VALHALLA	No	Valhalla channel webhook
SLACK_WEBHOOK_LOOM	No	Loom channel webhook
SLACK_WEBHOOK_LEYDEN	No	Leyden channel webhook
SLACK_WEBHOOK_PANAMA	No	Panama channel webhook
SLACK_WEBHOOK_JEP	No	Java JEP/version updates channel webhook
GEMINI_API_KEY	No*	Gemini provider key
OPENAI_API_KEY	No*	OpenAI provider key

*Required only for the provider you use.

Optional variables:

Name	Description
GEMINI_MODEL	Primary Gemini model (default: gemini-2.5-flash)
GEMINI_FALLBACK_MODEL	Fallback model on retries (default: gemini-2.5-flash-lite)
SUMMARY_MAX_ARTICLES	Max article count used for AI summarization (default: 12)
PROJECT_DETAIL_MAX_ARTICLES	Max article count for detailed Amber/Valhalla summaries (default: 20)

5) Run workflow manually

Use GitHub Actions Run workflow on Java Digest — Günlük Özet.

mode=test automatically enables FORCE_SUMMARY=true, which sends a test summary even when there are no unseen items, and skips state.json / docs persistence.

Runtime Schedule

Defined in .github/workflows/daily-digest.yml:

• Daily digest: 0 8 * * * (08:00 UTC)
• Weekly digest: 0 9 * * 1 (Monday 09:00 UTC)

Local Run

# Build
mvn -q package -DskipTests

# Basic run
java -jar target/java-digest-1.0-SNAPSHOT.jar

# Gemini run
export GEMINI_API_KEY="..."
export GEMINI_MODEL="gemini-2.5-flash"          # optional
export GEMINI_FALLBACK_MODEL="gemini-2.5-flash-lite"  # optional
export SUMMARY_MAX_ARTICLES="12"                # optional
export PROJECT_DETAIL_MAX_ARTICLES="20"         # optional
export FORCE_SUMMARY="true"                     # optional test mode
java -jar target/java-digest-1.0-SNAPSHOT.jar

Current Summary Behavior

• AI summaries prioritize: amber, valhalla, loom, panama, leyden, openjdk-jep
• Per-link short summaries are generated and shown under each link when possible
• Amber and Valhalla channels receive long-form detailed channel summaries
• Gemini calls include retry and model fallback strategy for 429/503
• If AI output format is malformed, parsing falls back to regex and then safe per-item fallback text

Architecture

GitHub Actions (cron + manual)
  -> Main
     -> parallel fetchers (RSS, mailing lists, JEP)
     -> StateManager filter
     -> AISummarizer (general + per-link + detailed project summaries)
     -> SlackNotifier (channel routing + payload formatting)
     -> DigestPageGenerator (docs/, optional)
     -> state update

Support

If this project helps you, please consider giving it a star on GitHub.

• Repository: umiitkose/java-newsletter
• You can also share feedback in the java-newsletter Slack workspace or open an issue.

License

MIT