Rsclub2_2andClaude Opus 5
209034724f
The ON4KST connection manager introduced in f8c04e7 uses
jdk.net.ExtendedSocketOptions to configure kernel side TCP keepalives. The
new dependency was added to module-info.java and to the jpackage Maven
plugin, but the CI and AUR builds do not use that plugin: they call jpackage
directly with a hardcoded --add-modules list that still lacked jdk.net.
Because jdk.net is not pulled in transitively, every packaged runtime image
shipped without the class while development runs against the full JDK and
kept working.
The resulting NoClassDefFoundError is an Error, so neither the catch in
configureSocket nor the surrounding catch (Exception) in openConnection
handled it. Running on a ScheduledExecutorService, the throwable was stored
in the task future and never surfaced, leaving the state machine stuck in
CONNECTING with no reconnect attempt and no user visible failure.
Add jdk.net to all 16 module lists, covering nightly artifacts, tagged
releases and both AUR PKGBUILDs, so releases are affected as well as
nightlies. Additionally catch LinkageError in configureSocket so a runtime
image without jdk.net degrades to application level heartbeats, and catch
Throwable in openConnection so an Error can no longer be swallowed by the
scheduler.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
KST4Contest
KST4Contest is a Java-based client for the ON4KST chat, developed for coordinated VHF, UHF and microwave contest operation.
The application is developed by Marc Fröhlich (DO5AMF) and since 2026 Philipp Wagner (DN9APW).
Start here
- Project website
- Download Stable, Beta and Nightly builds
- Online manual
- GitHub wiki
- Issues and bug reports
- Development roadmap
What KST4Contest does
KST4Contest combines the ON4KST chat with information that is useful when coordinating contacts during a contest.
Among other things, it can:
- display and filter stations from the supported ON4KST chat categories;
- derive band and frequency information from chat messages and station names;
- maintain Worked and NOT QRV information for the available bands;
- calculate station priorities from distance, activity and other available information;
- manage internal skeds and received Win-Test skeds;
- use AirScout information when evaluating possible aircraft-scatter contacts;
- display stations, paths and additional propagation information on maps;
- exchange information with supported logging programs, Win-Test, PSTRotator and a local DX Cluster interface;
- provide configurable automatic replies for recurring chat requests.
Calculated scores, aircraft-scatter information and path assessments are operating aids. They depend on the available data and should not be treated as guarantees that a contact is possible.
Installation
Ready-to-use packages are available for Windows, Linux and macOS. These packages include the required Java runtime, so a separate Java installation is normally not necessary.
Use the central download page to select the appropriate build:
- Stable is intended for normal contest operation.
- Beta contains changes that are being prepared for a stable release.
- Nightly contains the latest automated development build and is mainly intended for testing.
Documentation
The documentation is available in German and English:
The Markdown sources used for the wiki and the generated PDF manuals are stored in github_docs.
Changes to operating behaviour should be documented together with their purpose and limitations. This is especially important for functions whose result depends on external data, heuristics or information derived from chat messages.
Building from source
Building KST4Contest requires JDK 21. The Maven Wrapper included in the repository should be used, so a separate Maven installation is not required.
Linux and macOS:
./mvnw clean test
./mvnw -B -DskipTests compile
Windows:
mvnw.cmd clean test
mvnw.cmd -B -DskipTests compile
Repository structure
src/main/java/– application source codesrc/test/– automated testsgithub_docs/– German and English manual sourceswebsite/– project website sourcespackaging/– platform-specific packaging files
CI status
Documentation
Builds
License
KST4Contest is distributed under the GNU General Public License v3.0.