Cannot send messages between several RabbitMQ exchanges

Question

I want to route multiple messages between several RabbitMQ exchanges. This is the routing table that I want to use:

// | exchange | type | routing key | queue |
// |-----------------------------------------------------------------|
// | processing | topic | processing.event.transaction | processing.transaction.queue |
// | database | topic | database.event.transaction | database.transaction.queue |
// | database | topic | database.event.api_attempts | database.api_attempts.queue |
// | database | topic | database.event.event_logs | database.event_logs.queue |

I have 3 modules which I want to configure to send messages this way:

REST API Module -> Gateway module
REST API Module -> Database Module

REST API Module configuration

String QUEUE_PROCESSING_TRANSACTION = "processing.transaction.queue";
String QUEUE_DATABASE_TRANSACTION = "database.transaction.queue";   
String QUEUE_DATABASE_API_ATTEMPT = "database.api_attempts.queue";
String QUEUE_DATABASE_EVENT_LOGS = "database.event_logs.queue";  
String EXCHANGE_PROCESSING = "processing";
String EXCHANGE_DATABASE = "database";  
String ROUTING_KEY_PROCESSING = "processing.event.transaction";
String ROUTING_KEY_DATABASE = "database.event.transaction"; 
String ROUTING_KEY_API_ATTEMPTS = "database.event.api_attempts";
String ROUTING_KEY_EVENT_LOGS = "database.event.event_logs";

channel = connection.createChannel();
channel.exchangeDeclare(EXCHANGE_PROCESSING, BuiltinExchangeType.TOPIC);
channel.exchangeDeclare(EXCHANGE_DATABASE, BuiltinExchangeType.TOPIC);

channel.queueDeclare(QUEUE_PROCESSING_TRANSACTION, false, false, false, null);
channel.queueDeclare(QUEUE_DATABASE_TRANSACTION, false, false, false, null);            
channel.queueDeclare(QUEUE_DATABASE_API_ATTEMPT, false, false, false, null);
channel.queueDeclare(QUEUE_DATABASE_EVENT_LOGS, false, false, false, null);

channel.queueBind(QUEUE_PROCESSING_TRANSACTION, EXCHANGE_PROCESSING, ROUTING_KEY_PROCESSING);
channel.queueBind(QUEUE_DATABASE_TRANSACTION, EXCHANGE_DATABASE, ROUTING_KEY_DATABASE);
channel.queueBind(QUEUE_DATABASE_API_ATTEMPT, EXCHANGE_DATABASE, ROUTING_KEY_API_ATTEMPTS);
channel.queueBind(QUEUE_DATABASE_EVENT_LOGS, EXCHANGE_DATABASE, ROUTING_KEY_EVENT_LOGS);

Sending Java objects to other modules:

TransactionsBean obj = new TransactionsBean();
obj.setId(Long.valueOf(111222333));
channel.basicPublish(EXCHANGE_PROCESSING, ROUTING_KEY_PROCESSING, null, SerializationUtils.serialize(obj));
channel.basicPublish(EXCHANGE_DATABASE, ROUTING_KEY_DATABASE, null, SerializationUtils.serialize(obj));

ApiAttemptsBean obj = new ApiAttemptsBean();
obj.setId(Long.valueOf(2332));
channel.basicPublish(EXCHANGE_DATABASE, ROUTING_KEY_API_ATTEMPTS, null, SerializationUtils.serialize(obj));

EventLogsBean obj = new EventLogsBean();
obj.setId(Long.valueOf(111222));
channel.basicPublish(EXCHANGE_DATABASE, ROUTING_KEY_EVENT_LOGS, null, SerializationUtils.serialize(obj));

Module Gateway configuration:

String QUEUE_PROCESSING_TRANSACTION = "processing.transaction.queue";
String QUEUE_DATABASE_TRANSACTION = "database.transaction.queue";   
String QUEUE_DATABASE_API_ATTEMPT = "database.api_attempts.queue";
String QUEUE_DATABASE_EVENT_LOGS = "database.event_logs.queue";  
String EXCHANGE_DATABASE = "database";  
String ROUTING_KEY_DATABASE = "database.event.transaction"; 
String ROUTING_KEY_API_ATTEMPTS = "database.event.api_attempts";
String ROUTING_KEY_EVENT_LOGS = "database.event.event_logs";

channel = connection.createChannel();
channel.exchangeDeclare(EXCHANGE_PROCESSING, BuiltinExchangeType.TOPIC);
channel.queueDeclare(QUEUE_PROCESSING_TRANSACTION, false, false, false, null);
channel.queueBind(QUEUE_PROCESSING_TRANSACTION, EXCHANGE_PROCESSING, ROUTING_KEY_PROCESSING);

Map<String, Consumer<byte[]>> queueToConsumer = new HashMap<>();
        queueToConsumer.put(QUEUE_DATABASE_TRANSACTION, this::process_transaction);
        queueToConsumer.put(QUEUE_DATABASE_API_ATTEMPT, this::process_api_attempt);
        queueToConsumer.put(QUEUE_DATABASE_EVENT_LOGS, this::process_event_logs);

        queueToConsumer.forEach((queueName, consumer) -> {
            try {
                channel.basicConsume(queueName, true, new DefaultConsumer(channel) {
                    @Override
                    public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties,
                            byte[] body) throws IOException {
                        consumer.accept(body);
                    }
                });
            } catch (IOException e) {
                e.printStackTrace();
            }
        });
    }

private void process_transaction(byte[] object) {
        TransactionsBean obj = (TransactionsBean) SerializationUtils.deserialize(object);
        System.out.println("!!!! Received id " + obj.getId() + " in gateway");
    }

    private void process_api_attempt(byte[] object) {
        ApiAttemptsBean obj = (ApiAttemptsBean) SerializationUtils.deserialize(object);
        System.out.println("!!!! Received id " + obj.getId() + " in gateway");
    }

    private void process_event_logs(byte[] object) {
        EventLogsBean obj = (EventLogsBean) SerializationUtils.deserialize(object);
        System.out.println("!!!! Received id " + obj.getId() + " in gateway");
    }

Module Database:

String QUEUE_PROCESSING_TRANSACTION = "processing.transaction.queue";
String QUEUE_DATABASE_TRANSACTION = "database.transaction.queue";
String QUEUE_DATABASE_API_ATTEMPT = "database.api_attempts.queue";
String QUEUE_DATABASE_EVENT_LOGS = "database.event_logs.queue";
String EXCHANGE_DATABASE = "database";  
String ROUTING_KEY_PROCESSING = "processing.event.transaction";
String ROUTING_KEY_DATABASE = "database.event.transaction"; 
String ROUTING_KEY_API_ATTEMPTS = "database.event.api_attempts";
String ROUTING_KEY_EVENT_LOGS = "database.event.event_logs";

channel = connection.createChannel();
channel.exchangeDeclare(EXCHANGE_DATABASE, BuiltinExchangeType.TOPIC);
channel.queueDeclare(QUEUE_DATABASE_TRANSACTION, false, false, false, null);            
channel.queueDeclare(QUEUE_DATABASE_API_ATTEMPT, false, false, false, null);
channel.queueDeclare(QUEUE_DATABASE_EVENT_LOGS, false, false, false, null);
channel.queueBind(QUEUE_DATABASE_TRANSACTION, EXCHANGE_DATABASE, ROUTING_KEY_DATABASE);
channel.queueBind(QUEUE_DATABASE_API_ATTEMPT, EXCHANGE_DATABASE, ROUTING_KEY_API_ATTEMPTS);
channel.queueBind(QUEUE_DATABASE_EVENT_LOGS, EXCHANGE_DATABASE, ROUTING_KEY_EVENT_LOGS);

Map<String, Consumer<byte[]>> queueToConsumer = new HashMap<>();
queueToConsumer.put(QUEUE_DATABASE_TRANSACTION, this::process_transaction);
queueToConsumer.put(QUEUE_DATABASE_API_ATTEMPT, this::process_api_attempt);
queueToConsumer.put(QUEUE_DATABASE_EVENT_LOGS, this::process_event_logs);

queueToConsumer.forEach((queueName, consumer) -> {
            try {
                channel.basicConsume(queueName, true, new DefaultConsumer(channel) {
                    @Override
                    public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties,
                            byte[] body) throws IOException {
                        consumer.accept(body);
                    }
                });
            } catch (IOException e) {
                e.printStackTrace();
            }
        });

private void process_transaction(byte[] object) {       
    TransactionsBean obj = (TransactionsBean) SerializationUtils.deserialize(object);
    System.out.println("!!!! Received id " + obj.getId() + " in database");
}

private void process_api_attempt(byte[] object) {
    ApiAttemptsBean obj = (ApiAttemptsBean) SerializationUtils.deserialize(object);
    System.out.println("!!!! Received id " + obj.getId() + " in database");
}

private void process_event_logs(byte[] object) {
    EventLogsBean obj = (EventLogsBean) SerializationUtils.deserialize(object);
    System.out.println("!!!! Received id " + obj.getId() + " in database");
}

But messages are delivered not properly:

11:33:00,783 ERROR [com.rabbitmq.client.impl.ForgivingExceptionHandler] (pool-17-thread-6) Consumer org.database.context.ContextServer$1@6fee6ab4 (amq.ctag-arvcrYNc61cslclCTAnpDQ) method handleDelivery for channel AMQChannel(amqp://guest@127.0.0.1:5672/,1) threw an exception for channel AMQChannel(amqp://guest@127.0.0.1:5672/,1): java.lang.ClassCastException: deployment.db.war//plugin.factories.TransactionsBean cannot be cast to deployment.database.war//org.plugin.factories.EventLogsBean

Looks like messages are not properly routed probably because my routing table is not correct.

Can you give me some guide how I can fix this issue?

EDIT: Error stack:

22:19:26,584 ERROR [com.rabbitmq.client.impl.ForgivingExceptionHandler] (pool-19-thread-6) Consumer org.database.context.ContextServer$1@49ee659f (amq.ctag-vjArBDtmtruIgeCMLipHGQ) method handleDelivery for channel AMQChannel(amqp://guest@127.0.0.1:5672/,1) threw an exception for channel AMQChannel(amqp://guest@127.0.0.1:5672/,1): java.lang.ClassCastException: deployment.db.war//org.plugin.database.bean.TransactionsBean cannot be cast to deployment.db.war//org.plugin.database.bean.ApiAttemptsBean
    at deployment.db.war//org.database.context.ContextServer.process_api_attempt(ContextServer.java:79)
    at deployment.db.war//org.database.context.ContextServer$1.handleDelivery(ContextServer.java:64)
    at deployment.db.war//com.rabbitmq.client.impl.ConsumerDispatcher$5.run(ConsumerDispatcher.java:149)
    at deployment.db.war//com.rabbitmq.client.impl.ConsumerWorkService$WorkPoolRunnable.run(ConsumerWorkService.java:104)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1135)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
    at java.base/java.lang.Thread.run(Thread.java:844)

22:19:26,586 INFO  [javax.enterprise.resource.webcontainer.jsf.config] (ServerService Thread Pool -- 111) Initializing Mojarra 2.2.13.SP5  for context '/rest_api'
22:19:26,619 INFO  [stdout] (pool-21-thread-6) !!!! Received id 2332 in gateway
22:19:26,667 ERROR [com.rabbitmq.client.impl.ForgivingExceptionHandler] (pool-19-thread-6) Consumer org.database.context.ContextServer$1@29ba98e4 (amq.ctag-RMVncG2xQn3KBJ561F9HNQ) method handleDelivery for channel AMQChannel(amqp://guest@127.0.0.1:5672/,1) threw an exception for channel AMQChannel(amqp://guest@127.0.0.1:5672/,1): java.lang.ClassCastException: deployment.db.war//org.plugin.database.bean.TransactionsBean cannot be cast to deployment.db.war//org.plugin.database.bean.EventLogsBean
    at deployment.db.war//org.database.context.ContextServer.process_event_logs(ContextServer.java:84)
    at deployment.db.war//org.database.context.ContextServer$1.handleDelivery(ContextServer.java:64)
    at deployment.db.war//com.rabbitmq.client.impl.ConsumerDispatcher$5.run(ConsumerDispatcher.java:149)
    at deployment.db.war//com.rabbitmq.client.impl.ConsumerWorkService$WorkPoolRunnable.run(ConsumerWorkService.java:104)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1135)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
    at java.base/java.lang.Thread.run(Thread.java:844)

22:19:26,669 INFO  [stdout] (pool-21-thread-6) !!!! Received id 111222 in gateway

Answer 1

In the Module Database you set all queue bindings with the same routing_key: ROUTING_KEY_DATABASE

channel.queueBind(QUEUE_DATABASE_TRANSACTION, EXCHANGE_DATABASE, ROUTING_KEY_DATABASE);
channel.queueBind(QUEUE_DATABASE_API_ATTEMPT, EXCHANGE_DATABASE, ROUTING_KEY_DATABASE);
channel.queueBind(QUEUE_DATABASE_EVENT_LOGS, EXCHANGE_DATABASE, ROUTING_KEY_DATABASE);

Probably should be:

channel.queueBind(QUEUE_DATABASE_TRANSACTION, EXCHANGE_DATABASE, ROUTING_KEY_DATABASE);
channel.queueBind(QUEUE_DATABASE_API_ATTEMPT, EXCHANGE_DATABASE, ROUTING_KEY_API_ATTEMPTS);
channel.queueBind(QUEUE_DATABASE_EVENT_LOGS, EXCHANGE_DATABASE, ROUTING_KEY_EVENT_LOGS);

It's just a copy-paste error (-:

Edit
The code now seems good, so a few things to check:

-1-
Did you clear the queues before running the new code (so there is no old messages)

-2-
Try adding breakpoints or at least println in:

public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                        consumer.accept(body);
                    }

Try to get some values from the envelope regarding the message routing key and original exchange.

EDIT 2

I checked it again, by eye everything looks good. The only thing I can give you is to better debug your code to understand what is the issue.

-1-
Did you try to login to the rabbitMQ UI to monitor the messages?

-2-
Try to add better logs, for instance, add the functino name in the println:

System.out.println("!!!! Received id " + obj.getId() + " in database");

changed with

System.out.println("process_transaction: Received id " + obj.getId() + " in database");

And do that inside all the function to know by the message where exactly you are.

-3-
From the envelope, you can envelope.getExchange() but also envelope. getRoutingKey() envelope. getRoutingKey() to see exactly how the message was called.