apache/beam · critical · IOException

SolaceIO.Read: Could not create a receiver from the Jcsmp…

Error message

SolaceIO.Read: Could not create a receiver from the Jcsmp session: session object is null.

What it means

SolaceIO.Read throws this IOException in JcsmpSessionService.createFlowReceiver when the JCSMP session object is null at the moment the reader tries to create a message flow receiver. It means the source could not establish a usable session to the Solace broker before subscribing, so reading cannot proceed. This is a fail-fast guard rather than a transient failure: the code checks `if (jcsmpSession != null)` and throws otherwise.

Solutions

Verify the broker connection parameters (host, VPN, username, password) are correct so the JCSMP session is actually created and connected before reading.
If using a custom SessionServiceFactory, ensure it returns a service whose `getJcsmpSession()` never returns null and that `session.connect()` was called.
Check pipeline logs for an earlier JCSMPException during session creation — fix that root cause (DNS, VPN name, auth) first.
Do not close or null out the session before the read pipeline finishes; guard lifecycle ordering in custom code.

Example fix

// before (custom factory)
public JcsmpSessionService create() {
  JCSMPProperties props = new JCSMPProperties();
  props.setProperty(JCSMPProperties.HOST, host);
  return new JcsmpSessionService(props); // session never connected
}
// after
public JcsmpSessionService create() {
  JCSMPProperties props = new JCSMPProperties();
  props.setProperty(JCSMPProperties.HOST, host);
  props.setProperty(JCSMPProperties.VPN_NAME, vpn);
  JCSMPException cause = null;
  JCSMPSession session = JCSMPFactory.onlyInstance().createSession(props);
  session.connect(); // ensure session is usable
  return new JcsmpSessionService(props);
}

Defensive patterns

Strategy: validation

Validate before calling

if (sessionService == null || sessionService.getJcsmpSession() == null) {
  throw new IllegalArgumentException("JCSMP session not initialized — check broker config/factory");
}

Try / catch

try { pipeline.run().waitUntilFinish(); } catch (IOException e) { if (e.getMessage().contains("session object is null")) { /* fix session init, resubmit */ } throw e; }

Prevention

Always verify session.connect() succeeds before starting the read pipeline
Never return partially initialized services from custom SessionServiceFactory implementations
Check pipeline logs for earlier JCSMPExceptions that null out the session

When it happens

Trigger: Calling SolaceIO.read() when the JcsmpSessionService was never initialized with a connected session — e.g. `createSession` failed earlier and null was propagated, a custom SessionServiceFactory returned a service whose session is null, or the session was closed/nulled before the pipeline started pulling from the queue.

Common situations: Wrong broker host/credentials causing session creation to silently produce null in a custom factory; a user-supplied `SessionServiceFactory` implementation returning a partially constructed service; session closed by another thread during pipeline teardown or restart; copy-pasted custom broker integration code that doesn't call `session.connect()`.

Related errors

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/c83e6f9feef37364. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/io/solace/src/main/java/org/apache/beam/sdk/io/solace/broker/JcsmpSessionService.java:154

      throw new IOException("SolaceIO.Write: Could not create producer, producer object is null");
    }
    return new SolaceMessageProducer(producer);
  }

  private MessageReceiver createFlowReceiver() throws JCSMPException, IOException {
    Queue queue = checkStateNotNull(queue(), "SolaceIO.Read: Queue is not set.");

    ConsumerFlowProperties flowProperties = new ConsumerFlowProperties();
    flowProperties.setEndpoint(queue);
    flowProperties.setAckMode(JCSMPProperties.SUPPORTED_MESSAGE_ACK_CLIENT);

    EndpointProperties endpointProperties = new EndpointProperties();
    endpointProperties.setAccessType(EndpointProperties.ACCESSTYPE_NONEXCLUSIVE);
    if (jcsmpSession != null) {
      return new SolaceMessageReceiver(
          createFlowReceiver(jcsmpSession, flowProperties, endpointProperties));
    }
    throw new IOException(
        "SolaceIO.Read: Could not create a receiver from the Jcsmp session: session object is"
            + " null.");
  }

  // The `@SuppressWarning` is needed here, because the checkerframework reports an error for the
  // first argument of the `createFlow` being null, even though the documentation allows it:
  // https://docs.solace.com/API-Developer-Online-Ref-Documentation/java/com/solacesystems/jcsmp/JCSMPSession.html#createFlow-com.solacesystems.jcsmp.XMLMessageListener-com.solacesystems.jcsmp.ConsumerFlowProperties-com.solacesystems.jcsmp.EndpointProperties-
  @SuppressWarnings("nullness")
  private static FlowReceiver createFlowReceiver(
      JCSMPSession jcsmpSession,
      ConsumerFlowProperties flowProperties,
      EndpointProperties endpointProperties)
      throws JCSMPException {
    return jcsmpSession.createFlow(null, flowProperties, endpointProperties);
  }

  private int connectReadSession() throws JCSMPException {
    if (jcsmpSession == null) {

View on GitHub (pinned to 12126d8942)