Track and expose node capabilities per connection

AxonServerConnection.supports(capability) reports whether the node this
connection currently reaches has advertised a given capability, so callers
can check upfront instead of calling an RPC and reacting to UNIMPLEMENTED.
Captured fresh from NodeInfo on every (re)connect in AxonServerManagedChannel,
so it reflects the actual connected node even across reconnects to a
different one.

Author: hjohn

pom.xml

@@ -44,7 +44,7 @@
         <sonar.organization>axoniq</sonar.organization>
         <sonar.host.url>https://sonarcloud.io</sonar.host.url>
 
-        <axonserver.api.version>2026.1.0</axonserver.api.version>
+        <axonserver.api.version>2026.2.0-SNAPSHOT</axonserver.api.version>
 
         <grpc.version>1.79.0</grpc.version>
         <protobuf.version>4.36.2</protobuf.version>

src/main/java/io/axoniq/axonserver/connector/AxonServerConnection.java

@@ -55,6 +55,18 @@ public interface AxonServerConnection {
      */
     boolean isConnected();
 
+    /**
+     * Indicates whether the Axon Server node this connection currently reaches supports the given {@code
+     * capability}. The result reflects the node reached by the most recent (re)connect, so it may change over time -
+     * for example when this connection moves to a different node in the cluster, or that node gets upgraded.
+     *
+     * @param capability the capability identifier to check, e.g. {@code "dcb:snapshot-aware-sourcing"}
+     * @return {@code true} if the currently connected node has advertised the given capability, {@code false} if it
+     * either does not support it, or has not advertised any capabilities at all (e.g. because it predates capability
+     * negotiation)
+     */
+    boolean supports(String capability);
+
     /**
      * Disconnects all communication channels and terminates any active network connections to AxonServer. No more
      * operations can be performed on this connection after invoking <em>{@code disconnect()}</em>.

src/main/java/io/axoniq/axonserver/connector/impl/AxonServerManagedChannel.java

@@ -34,6 +34,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Queue;
+import java.util.Set;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.ScheduledExecutorService;
@@ -63,6 +64,7 @@ public class AxonServerManagedChannel extends ManagedChannel {
     private final long connectTimeout;
 
     private final AtomicReference<ManagedChannel> activeChannel = new AtomicReference<>();
+    private final AtomicReference<Set<String>> capabilities = new AtomicReference<>();
     private final AtomicBoolean shutdown = new AtomicBoolean();
     private final AtomicBoolean suppressErrors = new AtomicBoolean();
     private final Queue<Runnable> connectListeners = new LinkedBlockingQueue<>();
@@ -143,6 +145,9 @@ private ManagedChannel connectChannel() {
                             new ServerAddress(primaryClusterInfo.getHostName(), primaryClusterInfo.getGrpcPort());
                     connection = connectionFactory.apply(serverAddress, context);
                 }
+                capabilities.set(primaryClusterInfo.hasCapabilities()
+                                          ? Set.copyOf(primaryClusterInfo.getCapabilities().getCapabilityList())
+                                          : null);
                 suppressErrors.set(false);
                 lastConnectException.set(null);
                 break;
@@ -414,6 +419,22 @@ public boolean isReady() {
         return getState(false) == ConnectivityState.READY;
     }
 
+    /**
+     * Indicates whether the node this channel is currently connected to supports the given {@code capability}.
+     * <p>
+     * The result reflects the node reached by the most recent (re)connect, so it may change across reconnects -
+     * for example after this channel moves to a different node in the cluster, or after that node is upgraded.
+     *
+     * @param capability the capability identifier to check, e.g. {@code "dcb:snapshot-aware-sourcing"}
+     * @return {@code true} if the currently connected node has advertised the given capability, {@code false} if it
+     * either does not support it, or has not advertised any capabilities at all (e.g. because it predates capability
+     * negotiation)
+     */
+    public boolean supports(String capability) {
+        Set<String> currentCapabilities = capabilities.get();
+        return currentCapabilities != null && currentCapabilities.contains(capability);
+    }
+
     private static class FailingCall<REQ, RESP> extends ClientCall<REQ, RESP> {
 
         @Override

src/main/java/io/axoniq/axonserver/connector/impl/ContextConnection.java

@@ -143,6 +143,11 @@ public boolean isConnected() {
         return connection.getState(false) == ConnectivityState.READY;
     }
 
+    @Override
+    public boolean supports(String capability) {
+        return connection.supports(capability);
+    }
+
     @Override
     public void disconnect() {
         doIfNotNull(controlChannel, ControlChannelImpl::disconnect);