TAK-Server Plugin - Smack.xml and plugin loader errors

Tobias Nix — Mon, 28 Jul 2025 21:58:12 +0000

Hey devs 👋,

I'm working on integrating a custom plugin into the TAK Server (takserver-sender-receiver-xmpp-server-plugin-1.0.12.jar) that uses the Smack XMPP library (v4.4.6). The plugin should forward messages to an Openfire XMPP server, but I'm running into two core issues:

1. takserver-plugins.sh Classpath Issue?

I'm unsure whether the takserver-plugins.sh script is correctly setting the classpath. Here's the file:
takserver-plugins.sh

#!/bin/sh
. ./setenv.sh

# Hier nur System-Properties, kein "-jar"!
export JDK_JAVA_OPTIONS="-Dloader.path=WEB-INF/lib-provided,WEB-INF/lib,WEB-INF/classes,/opt/tak/lib,/opt/tak/lib/deps -Dio.netty.tmpdir=/opt/tak -Djava.io.tmpdir=/opt/tak -Dio.netty.native.workdir=/opt/tak -Djava.net.preferIPv4Stack=true -Djava.security.egd=file:/dev/./urandom -DIGNITE_UPDATE_NOTIFIER=false -DIGNITE_QUIET=true -Djdk.tls.client.protocols=TLSv1.2 -Dsmack.xmlparser=org.jivesoftware.smack.xml.xpp3.Xpp3XmlPullParserFactory"

exec java -server -XX:+AlwaysPreTouch -XX:+UseG1GC -XX:+ScavengeBeforeFullGC -XX:+DisableExplicitGC -Xmx${PLUGIN_MANAGER_MAX_HEAP}m -jar takserver-pm.jar "$@"

All .jar files are in /opt/tak/lib or /opt/tak/lib/deps, and the plugin starts loading—but maybe loader.path or the way -jar takserver-pm.jar is invoked interferes?

Is there a better way to ensure the Smack library dependencies and plugin JAR are correctly picked up?

2. Smack Initialization Error: XML Parser Not Found

The TAK Server logs show this when the plugin attempts to initialize, before I edited the takserver-plugins.sh:

2025-07-28-11:20:24.823 [ForkJoinPool-3-worker-1] tak.server.plugins.XmppPlugin - Starting XMPP Plugin...
2025-07-28-11:20:24.823 [ForkJoinPool-3-worker-1] tak.server.plugins.XmppPlugin - Initialisiere XMPP mit joy@189.65.91.182:5222 (EmpfÃ¤nger: james@openfire.recce8.heer)
2025-07-28-11:20:24.867 [main] t.s.p.messaging.PluginMessenger - starting PluginMessenger
2025-07-28-11:20:24.868 [main] t.s.plugins.service.PluginService - Started PluginService in 58.843 seconds (process running for 77.705)
Exception in thread "ForkJoinPool-3-worker-1" java.lang.ExceptionInInitializerError
    at org.jivesoftware.smack.Smack.getVersion(Smack.java:38)
    at org.jivesoftware.smack.Smack.ensureInitialized(Smack.java:64)
    at org.jivesoftware.smack.ConnectionConfiguration.<clinit>(ConnectionConfiguration.java:116)
    at tak.server.plugins.XmppPlugin.start(XmppPlugin.java:55)
    at tak.server.plugins.PluginBase.internalStart(PluginBase.java:39)
    at tak.server.plugins.PluginStarter.lambda$startReceiverPlugins$9(PluginStarter.java:221)
    at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1395)
    at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:373)
    at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1182)
    at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1655)
    at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1622)
    at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:165)
Caused by: java.lang.IllegalStateException: Could not parse Smack configuration file
    at org.jivesoftware.smack.SmackInitialization.<clinit>(SmackInitialization.java:106)
    ... 12 more
Caused by: java.lang.IllegalStateException: No XmlPullParserFactory registered with Service Provider Interface (SPI). Is smack-xmlparser-xpp3 or smack-xmlparser-stax in classpath?
    at org.jivesoftware.smack.xml.SmackXmlParser.getXmlPullParserFactory(SmackXmlParser.java:41)
    at org.jivesoftware.smack.xml.SmackXmlParser.newXmlParser(SmackXmlParser.java:65)
    at org.jivesoftware.smack.util.PacketParserUtils.getParserFor(PacketParserUtils.java:80)
    at org.jivesoftware.smack.SmackInitialization.processConfigFile(SmackInitialization.java:159)
    at org.jivesoftware.smack.SmackInitialization.processConfigFile(SmackInitialization.java:154)
    at org.jivesoftware.smack.SmackInitialization.<clinit>(SmackInitialization.java:103)
    ... 12 more

But these files are present:

tak-admin@tak-server:/opt/tak/lib$ tree
.
├── deps
│   ├── jxmpp-core-1.1.0.jar
│   ├── jxmpp-jid-1.1.0.jar
│   ├── jxmpp-util-cache-1.1.0.jar
│   ├── minidns-client-1.0.5.jar
│   ├── minidns-core-1.0.5.jar
│   ├── smack-core-4.4.6.jar
│   ├── smack-debug-4.4.6.jar
│   ├── smack-extensions-4.4.6.jar
│   ├── smack-im-4.4.6.jar
│   ├── smack-tcp-4.4.6.jar
│   ├── smack-xmlparser-4.4.6.jar
│   ├── smack-xmlparser-stax-4.4.6.jar
│   ├── smack-xmlparser-xpp3-4.4.6.jar
│   └── xpp3-1.1.4c.jar
└── takserver-sender-receiver-xmpp-server-plugin-1.0.12.jar

Still, Smack doesn't detect the XML parser. Any idea how to properly register the parser or make Smack pick it up?

For the sake of completeness, here my plugin code:

package tak.server.plugins;

import java.lang.invoke.MethodHandles;

import org.jivesoftware.smack.AbstractXMPPConnection;
import org.jivesoftware.smack.chat2.Chat;
import org.jivesoftware.smack.chat2.ChatManager;
import org.jivesoftware.smack.tcp.XMPPTCPConnection;
import org.jivesoftware.smack.tcp.XMPPTCPConnectionConfiguration;
import org.jxmpp.jid.EntityBareJid;
import org.jxmpp.jid.impl.JidCreate;
import org.jxmpp.stringprep.XmppStringprepException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import atakmap.commoncommo.protobuf.v1.MessageOuterClass.Message;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

/**
 * TAK Plugin: Leitet empfangene TAK Nachrichten per XMPP an einen OpenFire-User weiter.
 */
@TakServerPlugin(name = "XMPP Forwarder Plugin", description = "Leitet TAK Nachrichten an XMPP weiter")
public class XmppPlugin extends MessageReceiverBase {

    private static final Logger logger = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());

    private AbstractXMPPConnection xmppConnection;
    private EntityBareJid xmppRecipient;

    private final ArrayBlockingQueue<Message> messageQueue = new ArrayBlockingQueue<>(1000);
    private static final ScheduledExecutorService worker = Executors.newScheduledThreadPool(1);
    private ScheduledFuture<?> future;

    @Override
public void start() {
    logger.info("Starting XMPP Plugin...");

    try {
        String username = (String) config.getProperty("xmppUsername");
        String password = (String) config.getProperty("xmppPassword");
        String domain = (String) config.getProperty("xmppDomain");
        String host = (String) config.getProperty("xmppHost");
        int port = (int) config.getProperty("xmppPort");
        String recipient = (String) config.getProperty("xmppRecipient");

        logger.info("Initialisiere XMPP mit {}@{}:{} (Empfänger: {})", username, host, port, recipient);

        xmppRecipient = JidCreate.entityBareFrom(recipient);

        XMPPTCPConnectionConfiguration connectionConfig = XMPPTCPConnectionConfiguration.builder()
            .setXmppDomain(domain)
            .setHost(host)
            .setPort(port)
            .setUsernameAndPassword(username, password)
            .setSecurityMode(XMPPTCPConnectionConfiguration.SecurityMode.ifpossible)  // try TLS, but fallback
            .setResource("tak-plugin")
            .setCompressionEnabled(false)
            .setSendPresence(false)
            .build();

        xmppConnection = new XMPPTCPConnection(connectionConfig);

        logger.info("Starte Verbindungsaufbau...");
        xmppConnection.connect();
        logger.info("Verbindung aufgebaut – jetzt login...");
        xmppConnection.login();
        logger.info("XMPP-Verbindung zu {} erfolgreich", domain);

        future = worker.scheduleWithFixedDelay(() -> {
            try {
                Message msg = messageQueue.take();
                forwardToXmpp(msg);
            } catch (InterruptedException e) {
                logger.error("Nachrichtenverarbeitung unterbrochen", e);
            }
        }, 0, 10, TimeUnit.MILLISECONDS);

    } catch (Exception e) {
        logger.error("Fehler beim Initialisieren der XMPP-Verbindung: {}", e.getMessage(), e);
    }
}

    @Override
    public void onMessage(Message message) {
        if (xmppConnection != null && xmppConnection.isConnected()) {
            messageQueue.offer(message);
            logger.info("TAK-Nachricht in Warteschlange gestellt");
        } else {
            logger.warn("XMPP-Verbindung nicht aktiv – Nachricht verworfen");
        }
    }

    private void forwardToXmpp(Message message) {
        try {
            String callsign = message.getPayload().getCotEvent().getDetail().getContact().getCallsign();
            String content = message.getPayload().getCotEvent().getDetail().getXmlDetail();

            String body = String.format("Von: %s\n%s", callsign, content);

            ChatManager chatManager = ChatManager.getInstanceFor(xmppConnection);
            Chat chat = chatManager.chatWith(xmppRecipient);
            chat.send(body);

            logger.info("Nachricht an {} gesendet:\n{}", xmppRecipient.asBareJid(), body);
        } catch (Exception e) {
            logger.error("Fehler beim Senden der Nachricht über XMPP", e);
        }
    }

    @Override
    public void stop() {
        if (future != null) {
            future.cancel(true);
        }
        if (xmppConnection != null && xmppConnection.isConnected()) {
            xmppConnection.disconnect();
            logger.info("XMPP-Verbindung wurde getrennt");
        }
    }
}

I hope these are all infos to help me out, if you need more I will them provide as fast as I can.

Thanks for your help, you're the best!

DEV Community: Tobias Nix

TAK-Server Plugin - Smack.xml and plugin loader errors

1. takserver-plugins.sh Classpath Issue?

2. Smack Initialization Error: XML Parser Not Found