Package io.zenoh.query

Class Queryable

  • All Implemented Interfaces:
    io.zenoh.session.SessionDeclaration , java.lang.AutoCloseable 
    
public class Queryable
 implements AutoCloseable, SessionDeclaration

    A queryable that allows to perform multiple queries on the specified KeyExpr.

    Its main purpose is to keep the queryable active as long as it exists.

    The declaring session holds a strong reference to it: dropping your own reference does NOT stop the queryable — it stays active until close (or undeclare) is called or the session is closed, whichever comes first. Only after that does it become eligible for garbage collection.

    Example using the default BlockingQueueHandler handler:

    try (Session session = Zenoh.open(config)) {
    var queryable = session.declareQueryable(keyExpr);
    BlockingQueue<Optional<Query>> receiver = queryable.getReceiver();
    assert receiver != null;
    while (true) {
        Optional<Query> wrapper = receiver.take();
        if (wrapper.isEmpty()) {
            break;
        }
        Query query = wrapper.get();
        query.reply(query.getKeyExpr(), "Example reply");
    }
}

    Example using a io.zenoh.handlers.Callback:

    try (Session session = Zenoh.open(config)) {
    var queryable = session.declareQueryable(keyExpr, query -> query.reply(query.getKeyExpr(), "Example reply");
}

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private final KeyExpr keyExpr

    • Constructor Summary

      Constructors 
      Constructor Description

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final KeyExpr getKeyExpr() The KeyExpr to which the subscriber is associated.
      final Boolean isValid()
      Unit undeclare() Undeclares the queryable.
      Unit close() Closes the queryable, equivalent to undeclare.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait