RocketMQ: Teach my wife how to understand DefaultMQProducer

public class DefaultMQProducer extends ClientConfig implements MQProducer

The DefaultMQProducer class is an entry point that applications use to deliver messages. Out of the box, it is possible to quickly create a producer using a no-argument constructor. It is mainly responsible for sending messages and supports synchronous, asynchronous, and Oneway sending modes, all of which support batch sending. The class provides getter/setter methods to adjust the parameters of the sender. DefaultMQProducer provides multiple send methods. Each send method is slightly different. Before using DefaultMQProducer, understand its intention in detail. Chapter 3: Teaching the wife how to be a producer and consumer of ordinary messages (synchronous, asynchronous and unidirectional)

public class Producer {
    public static void main(String[] args) throws MQClientException {
        // Create a producer with the specified group name
        DefaultMQProducer producer = new DefaultMQProducer("ProducerGroupName");

        // Start the producer
        producer.start();

        for (int i = 0; i < 128; i++)
            try {
            	// Build the message
                Message msg = new Message("TopicTest"."TagA"."OrderID188"."Hello world".getBytes(RemotingHelper.DEFAULT_CHARSET));

                // Synchronize sending
                SendResult sendResult = producer.send(msg);

                // Prints the sending result
                System.out.printf("%s%n", sendResult);
            } catch(Exception e) { e.printStackTrace(); } producer.shutdown(); }}Copy the code

Note: This class is thread-safe. After configuration and startup, it can be shared safely between multiple threads.

• producerGroup

  private String producerGroup

  The group name of the producer. The same group name indicates that the producer instances belong conceptually to the same group. This is important for transaction messages. If the original producer crashes after the transaction, the broker can contact different instances of producers in the same group to commit or roll back the transaction.

  Default value: DEFAULT_PRODUCER

  Note: by the Numbers, letters, underscores, shaft (-), a vertical bar (|) or percent composition; Cannot be empty; The length cannot exceed 255.

• defaultMQProducerImpl

  protected final transient DefaultMQProducerImpl defaultMQProducerImpl

  The internal default implementation of the producer, which is automatically initialized internally when the producer is constructed, provides the internal implementation of most methods.

• createTopicKey

  private String createTopicKey = MixAll.AUTO_CREATE_TOPIC_KEY_TOPIC

  When a message is sent, a topic that does not exist on the server is automatically created. You need to specify a Key that can be used to configure the default route for the topic from which the message is sent.

  Default value: TBW102

  Suggestion: Use this function for test or demo. Do not enable automatic creation and configuration in the production environment.

• defaultTopicQueueNums

  private volatile int defaultTopicQueueNums = 4

  The default number of queues when creating a topic.

  Default value: 4

• sendMsgTimeout

  private int sendMsgTimeout = 3000

  The timeout period for sending messages.

  Default value: 3000 milliseconds

  Suggestion: It is not recommended to change this value. The value should be consistent with sendTimeout in the Broker configuration. Sending timeout can be changed temporarily.

• compressMsgBodyOverHowmuch

  private int compressMsgBodyOverHowmuch = 1024 * 4

  Compressed message body threshold. Message bodies larger than 4K are compressed by default.

  Default value: 1024 x 4 (unit: byte

  Suggestion: through DefaultMQProducerImpl setZipCompressLevel method set compression rate (defaults to 5, optional range [0, 9]); Through DefaultMQProducerImpl. TryToCompressMessage method to test the compressLevel and compressMsgBodyOverHowmuch optimal value.

• retryTimesWhenSendFailed

  private int retryTimesWhenSendFailed = 2

  In synchronous mode, the maximum number of internal attempts to resend a message before sending back failed.

  Default value: 2. By default, a message can be delivered for a maximum of three times.

  Note: In extreme cases, this can lead to duplicate messages.

• retryTimesWhenSendAsyncFailed

  private int retryTimesWhenSendAsyncFailed = 2

  In asynchronous mode, the maximum number of internal attempts to resend a message before sending a message fails.

  Default value: 2. By default, a message can be delivered for a maximum of three times.

  Note: In extreme cases, this can lead to duplicate messages.

• retryAnotherBrokerWhenNotStoreOK

  private boolean retryAnotherBrokerWhenNotStoreOK = false

  Whether to retry other brokers if message saving fails in synchronous mode.

  Default value: false

  Note: When this configuration is turned off, the retryTimesWhenSendFailed configuration will be ignored in the case of non-post exceptions.

• maxMessageSize

  private int maxMessageSize = 1024 * 1024 * 4

  The maximum size of a message. The message fails to be sent when the number of bytes exceeds maxMessageSize.

  Default value: 1024 x 1024 x 4 (unit: byte

• traceDispatcher

  private TraceDispatcher traceDispatcher = null

  After message tracing is enabled, this class records messages consumed by message producers, message storing brokers, and consumers as links through hooks. When constructing a producer, the constructor parameter enableMsgTrace determines whether to create the object.

1. createTopic

   public void createTopic(String key, String newTopic, int queueNum)

   Create a topic on the broker.

   • Input parameter description:

     type	Whether must	The default value	Range of values	instructions
     String	is			Access key.
     opic	String	is
     eNum	int	is	0	(0, maxIntValue]

   • Return value description:

     void

   • Exception description:

     MQClientException – The producer state is not Running; No client exception such as broker was found.

2. createTopic

   public void createTopic(String key, String newTopic, int queueNum, int topicSysFlag)

   Create a topic on the broker.

   • Input parameter description:

     type	Whether must	The default value	Range of values	instructions
     String	is			Access key.
     opic	String	is
     eNum	int	is	0	(0, maxIntValue]
     cSysFlag	int	is	0

   • Return value description:

     void

   • Exception description:

     MQClientException – The producer state is not Running; No client exception such as broker was found.

3. earliestMsgStoreTime

   public long earliestMsgStoreTime(MessageQueue mq)

   Example Query the earliest message storage time.

   • Input parameter description:

     type	Whether must	The default value	Range of values	instructions
     MessageQueue	is			The message queue to query

   • Return value description:

     Specifies the earliest time a message is stored in the queue. Unit: millisecond.

   • Exception description:

     MQClientException – The producer state is not Running; Broker not found; Broker returns failed; The network is abnormal. Client exceptions such as thread interruption.

4. fetchPublishMessageQueues

   public List<MessageQueue> fetchPublishMessageQueues(String topic)

   Gets the message queue for the topic.

   • Input parameter description:

     type	Whether must	The default value	Range of values	instructions
     c	String	is

   • Return value description:

     Incoming message queue under topic.

   • Exception description:

     MQClientException – The producer state is not Running; Broker not found; Broker returns failed; The network is abnormal. Client exceptions such as thread interruption.

5. maxOffset

   public long maxOffset(MessageQueue mq)

   Query the maximum physical offset of a message queue.

   • Input parameter description:

     type	Whether must	The default value	Range of values	instructions
     MessageQueue	is			The message queue to query

   • Return value description:

     The maximum physical offset of a given message queue.

   • Exception description:

     MQClientException – The producer state is not Running; Broker not found; Broker returns failed; The network is abnormal. Client exceptions such as thread interruption.

6. minOffset

   public long minOffset(MessageQueue mq)

   Query the minimum physical offset for a given message queue.

   • Input parameter description:

     type	Whether must	The default value	Range of values	instructions
     MessageQueue	is			The message queue to query

   • Return value description:

     The minimum physical offset for a given message queue.

   • Exception description:

     MQClientException – The producer state is not Running; Broker not found; Broker returns failed; The network is abnormal. Client exceptions such as thread interruption.

7. queryMessage

   public QueryResult queryMessage(String topic, String key, int maxNum, long begin, long end)

   Query messages by keyword.

   • Input parameter description:

     type	Whether must	The default value	Range of values	instructions
     c	String	is
     String	no	null		Find the keyword
     um	int	is
     n	long	is
     long	is			End time stamp, in milliseconds

   • Return value description:

     The set of messages queried.

   • Exception description:

     MQClientException – The producer state is not Running; Broker not found; Broker returns failed; Network exceptions Client exceptions Client exceptions. InterruptedException – Thread interruption.

8. searchOffset

   public long searchOffset(MessageQueue mq, long timestamp)

   Finds the physical offset of the message queue at the specified time.

   • Input parameter description:

     type	Whether must	The default value	Range of values	instructions
     MessageQueue	is			The message queue to query.
     stamp	long	is

   • Return value description:

     The physical offset of the message queue at the specified time.

   • Exception description:

     MQClientException – The producer state is not Running; Broker not found; Broker returns failed; The network is abnormal. Client exceptions such as thread interruption.

9. send

   public SendResult send(Collection<Message> msgs)

   Synchronously send messages in batches. The maximum number of internal attempts to resend a message before returning a send failure (see the retryTimesWhenSendFailed property). If the sending queue is not specified, the polling policy is adopted by default.

   • Input parameter description:

     type	Whether must	The default value	Range of values	instructions
     Collection	is			A collection of messages to be sent. The messages within the collection must belong to the same topic.

   • Return value description:

     Result of sending batch messages, including msgId, sending status, etc.

   • Exception description:

     Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. An error has occurred with mqBrokerException-broker. InterruptedException – The sending thread is interrupted. RemotingTooMuchRequestException – send timeout.

10. send

    public SendResult send(Collection<Message> msgs, long timeout)

    Synchronous batch sends the message, if not completed within a specified timeout message delivery, throws RemotingTooMuchRequestException. The maximum number of internal attempts to resend a message before returning a send failure (see the retryTimesWhenSendFailed property). If the sending queue is not specified, the polling policy is adopted by default.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Collection	is			A collection of messages to be sent. The messages within the collection must belong to the same topic.
      out	long	is	seesendMsgTimeoutattribute

    • Return value description:

      Result of sending batch messages, including msgId, sending status, etc.

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. An error has occurred with mqBrokerException-broker. InterruptedException – The sending thread is interrupted. RemotingTooMuchRequestException – send timeout.

11. send

    public SendResult send(Collection<Message> msgs, MessageQueue messageQueue)

    Sends messages synchronously to a given queue in batches.

    Note: Specifying queues means that all messages are the same topic.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Collection	is			A collection of messages to be sent. The messages within the collection must belong to the same topic.
      ageQueue	MessageQueue	is

    • Return value description:

      Result of sending batch messages, including msgId, sending status, etc.

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. An error has occurred with mqBrokerException-broker. InterruptedException – The sending thread is interrupted. RemotingTooMuchRequestException – send timeout.

12. send

    public SendResult send(Collection<Message> msgs, MessageQueue messageQueue, long timeout)

    Send message to a given queue synchronization in bulk, if not completed within a specified timeout message delivery, throws RemotingTooMuchRequestException.

    Note: Specifying queues means that all messages are the same topic.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Collection	is			A collection of messages to be sent. The messages within the collection must belong to the same topic.
      out	long	is	seesendMsgTimeoutattribute
      ageQueue	MessageQueue	is

    • Return value description:

      Result of sending batch messages, including msgId, sending status, etc.

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. An error has occurred with mqBrokerException-broker. InterruptedException – The sending thread is interrupted. RemotingTooMuchRequestException – send timeout.

13. send

    public SendResult send(Message msg)

    The message is sent in synchronous mode, and this method returns only when the sending process is complete. The maximum number of internal attempts to resend a message before returning a send failure (see the retryTimesWhenSendFailed property). If the sending queue is not specified, the polling policy is adopted by default.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.

    • Return value description:

      Result of sending a message, including msgId, sending status, etc.

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. An error has occurred with mqBrokerException-broker. InterruptedException – The sending thread is interrupted. RemotingTooMuchRequestException – send timeout.

14. send

    public SendResult send(Message msg, long timeout)

    Send message to synchronous mode, if not completed within a specified timeout message delivery, throws RemotingTooMuchRequestException. This method returns only when the send process is complete. The maximum number of internal attempts to resend a message before returning a send failure (see the retryTimesWhenSendFailed property). If the sending queue is not specified, the polling policy is adopted by default.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      out	long	is	seesendMsgTimeoutattribute

    • Return value description:

      Result of sending a message, including msgId, sending status, etc.

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. An error has occurred with mqBrokerException-broker. InterruptedException – The sending thread is interrupted. RemotingTooMuchRequestException – send timeout.

15. send

    public SendResult send(Message msg, MessageQueue mq)

    Sends a single message synchronously to the specified message queue. This method returns only when the send process is complete.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      MessageQueue	is			Queue of messages to be delivered.

    • Return value description:

      Result of sending a message, including msgId, sending status, etc.

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. An error has occurred with mqBrokerException-broker. InterruptedException – The sending thread is interrupted. RemotingTooMuchRequestException – send timeout.

16. send

    public SendResult send(Message msg, MessageQueue mq, long timeout)

    Send a single message to a specified message queue synchronization, if not completed within a specified timeout message delivery, throws RemotingTooMuchRequestException. This method returns only when the send process is complete.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      out	long	is	seesendMsgTimeoutattribute
      MessageQueue	is			Queue of messages to be delivered. Specifying a queue means that the messages to be delivered are all the same topic.

    • Return value description:

      Result of sending a message, including msgId, sending status, etc.

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. An error has occurred with mqBrokerException-broker. InterruptedException – The sending thread is interrupted. RemotingTooMuchRequestException – send timeout.

17. send

    public void send(Message msg, MessageQueue mq, SendCallback sendCallback)

    Send a single message asynchronously to the specified message queue. Send a single message asynchronously and return sendCallback in case of success or exception. Therefore, sendCallback cannot be null when sending an asynchronous message; otherwise, NullPointerException will be thrown during the callback. Asynchronous transmission, before send success, its internal will try to send a message the maximum times (see retryTimesWhenSendAsyncFailed properties).

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      MessageQueue	is			Queue of messages to be delivered. Specifying a queue means that the messages to be delivered are all the same topic.
      Callback	SendCallback	is

    • Return value description:

      void

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. InterruptedException – The sending thread is interrupted.

18. send

    public void send(Message msg, MessageQueue mq, SendCallback sendCallback, long timeout)

    Send a single message asynchronously to the specified message queue. Send a single message asynchronously and return sendCallback in case of success or exception. Therefore, sendCallback cannot be null when sending an asynchronous message; otherwise, NullPointerException will be thrown during the callback. If the message not sent successfully within a specified time, the callback method will receive RemotingTooMuchRequestException anomalies. Asynchronous transmission, before send success, its internal will try to send a message the maximum times (see retryTimesWhenSendAsyncFailed properties).

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      MessageQueue	is			Queue of messages to be delivered.
      Callback	SendCallback	is
      out	long	is	seesendMsgTimeoutattribute

    • The returned value is void

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. InterruptedException – The sending thread is interrupted.

19. send

    public SendResult send(Message msg, MessageQueueSelector selector, Object arg)

    Send messages synchronously to queues calculated by MessageQueueSelector.

    You can send a certain kind of message to a fixed queue through the self-implementing MessageQueueSelector interface. For example, post a status change message for the same order to a fixed queue.

    Note: This message failed to be sent internally and will not be retried.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      ctor	MessageQueueSelector	is
      Object	no			Parameter object to be used by the queue selector.

    • Return value description:

      Result of sending a message, including msgId, sending status, etc.

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. An error has occurred with mqBrokerException-broker. InterruptedException – The sending thread is interrupted. RemotingTooMuchRequestException – send timeout.

20. send

    public SendResult send(Message msg, MessageQueueSelector selector, Object arg, long timeout)

    Send messages synchronously to the queue calculated by MessageQueueSelector and specify a send timeout.

    You can send a certain kind of message to a fixed queue through the self-implementing MessageQueueSelector interface. For example, post a status change message for the same order to a fixed queue.

    Note: This message failed to be sent internally and will not be retried.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      ctor	MessageQueueSelector	is
      Object	no			Parameter object to be used by the queue selector.
      out	long	is	seesendMsgTimeoutattribute

    • Return value description:

      Result of sending a message, including msgId, sending status, etc.

    • Exception description: MQclientexception-broker does not exist or not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. An error has occurred with mqBrokerException-broker. InterruptedException – The sending thread is interrupted. RemotingTooMuchRequestException – send timeout.

21. send

    public void send(Message msg, MessageQueueSelector selector, Object arg, SendCallback sendCallback)

    Send a single message asynchronously to the queue calculated by MessageQueueSelector, send it asynchronously and return it directly, and call sendCallback in case of success or exception, so the sendCallback parameter cannot be null when sending it asynchronously. Otherwise a NullPointerException will be thrown during the callback. Asynchronous transmission, before send success, its internal will try to send a message the maximum times (see retryTimesWhenSendAsyncFailed properties).

    You can send a certain kind of message to a fixed queue through the self-implementing MessageQueueSelector interface. For example, post a status change message for the same order to a fixed queue.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      ctor	MessageQueueSelector	is
      Object	no			Parameter object to be used by the queue selector.
      Callback	SendCallback	is

    • Return value description:

      void

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. InterruptedException – The sending thread is interrupted.

22. send

    public void send(Message msg, MessageQueueSelector selector, Object arg, SendCallback sendCallback, long timeout)

    Send a single message asynchronously to the queue calculated by MessageQueueSelector, send it asynchronously and return it directly, and call sendCallback in case of success or exception, so the sendCallback parameter cannot be null when sending it asynchronously. Otherwise a NullPointerException will be thrown during the callback. Asynchronous transmission, before send success, its internal will try to send a message the maximum times (see retryTimesWhenSendAsyncFailed properties).

    You can send a certain kind of message to a fixed queue through the self-implementing MessageQueueSelector interface. For example, post a status change message for the same order to a fixed queue.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      ctor	MessageQueueSelector	is
      Object	no			Parameter object to be used by the queue selector.
      Callback	SendCallback	is
      out	long	is	seesendMsgTimeoutattribute

    • Return value description:

      void

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. InterruptedException – The sending thread is interrupted.

23. send

    public void send(Message msg, SendCallback sendCallback)

    When sending a single message asynchronously, sendCallback will be returned directly and will be called back if the message is successfully sent or if an exception occurs. Therefore, the sendCallback parameter cannot be null in asynchronous sending; otherwise, NullPointerException will be thrown during the callback. Asynchronous transmission, before send success, its internal will try to send a message the maximum times (see retryTimesWhenSendAsyncFailed properties).

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      Callback	SendCallback	is

    • Return value description:

      void

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. InterruptedException – The sending thread is interrupted.

24. send

    public void send(Message msg, SendCallback sendCallback, long timeout)

    When sending a single message asynchronously, sendCallback will be returned directly and will be called back if the message is successfully sent or if an exception occurs. Therefore, the sendCallback parameter cannot be null in asynchronous sending; otherwise, NullPointerException will be thrown during the callback. Asynchronous transmission, before send success, its internal will try to send a message the maximum times (see retryTimesWhenSendAsyncFailed properties).

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      Callback	SendCallback	is
      out	long	is	seesendMsgTimeoutattribute

    • Return value description:

      void

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. InterruptedException – The sending thread is interrupted.

25. sendMessageInTransaction

    public TransactionSendResult sendMessageInTransaction(Message msg, LocalTransactionExecuter tranExecuter, final Object arg)

    Send a transaction message. This class is not implemented by default and throws a RuntimeException. See also: TransactionMQProducer class.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Transaction message to be delivered
      Executer	LocalTransactionExecuter	is
      Object	is			Parameter object used by the local transaction executor

    • Return value description:

      For transaction results, see the LocalTransactionState class.

    • Exception description:

      RuntimeException – Always throws this exception.

26. sendMessageInTransaction

    public TransactionSendResult sendMessageInTransaction(Message msg, final Object arg)

    Send a transaction message. This class is not implemented by default and throws a RuntimeException. See also: TransactionMQProducer class.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Transaction message to be delivered
      Object	is			Parameter object used by the local transaction executor

    • Return value description:

      For transaction results, see the LocalTransactionState class.

    • Exception description:

      RuntimeException – Always throws this exception.

27. sendOneway

    public void sendOneway(Message msg)

    As oneway messages are sent, the broker does not respond to any execution results, similar to UDP. It has maximum throughput but messages can be lost.

    This method can be used when the volume of messages is large, high throughput is sought, and message loss is allowed.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Message to be delivered

    • Return value description:

      void

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. InterruptedException – The sending thread is interrupted.

28. sendOneway

    public void sendOneway(Message msg, MessageQueue mq)

    Messages are sent oneway to a specified queue, and the broker does not respond to any execution results, similar to UDP. It has maximum throughput but messages can be lost.

    This method can be used when the volume of messages is large, high throughput is sought, and message loss is allowed.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Message to be delivered
      MessageQueue	is			Queue of messages to be delivered

    • The returned value is void

    • Exception description: MQclientexception-broker does not exist or not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. InterruptedException – The sending thread is interrupted.

29. sendOneway

    public void sendOneway(Message msg, MessageQueueSelector selector, Object arg)

    Messages are sent oneway to queues calculated via MessageQueueSelector. The broker does not respond to any execution results, similar to UDP. It has maximum throughput but messages can be lost.

    This method can be used when the volume of messages is large, high throughput is sought, and message loss is allowed.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      Message	is			Messages to be sent.
      ctor	MessageQueueSelector	is
      Object	no			Parameter object to be used by the queue selector.

    • Return value description:

      void

    • Exception description:

      Mqclientexception-broker does not exist or was not found; Namesrv address is empty; Client exceptions such as the routing information of the topic are not found. RemotingException – Network exception. InterruptedException – The sending thread is interrupted.

30. shutdown

    public void shutdown()

    Close the current producer instance and release the associated resources.

    • Input parameter description:

      No.

    • Return value description:

      void

    • Exception description:

31. start

    public void start()

    Start the producer instance. This method must be called before a message can be sent or queried. It performs a number of internal initializations, such as checking configuration, establishing a connection with NamesRV, starting a series of scheduled tasks such as heartbeats, and so on.

    • Input parameter description:

      No.

    • Return value description:

      void

    • Exception description:

      MQClientException – Failed during initialization.

32. viewMessage

    public MessageExt viewMessage(String offsetMsgId)

    Query messages based on the given msgId.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      etMsgId	String	is

    • Return value description:

      Return MessageExt with topic name, message title, message ID, consumption count, producer host, etc.

    • Exception description:

      RemotingException – An error occurred at the network layer. An error has occurred with mqBrokerException-broker. InterruptedException – The thread is interrupted. MQClientException – The producer state is not Running; MsgId illegal etc.

33. viewMessage

    public MessageExt viewMessage(String topic, String msgId)

    Query messages based on the given msgId and specify a topic.

    • Input parameter description:

      type	Whether must	The default value	Range of values	instructions
      d	String	is
      c	String	is

    • Return value description:

      Return MessageExt with topic name, message title, message ID, consumption count, producer host, etc.

    • Exception description:

      RemotingException – An error occurred at the network layer. An error has occurred with mqBrokerException-broker. InterruptedException – The thread is interrupted. MQClientException – The producer state is not Running; MsgId illegal etc.

Reference: github.com/apache/rock…