Project: Apache RocketMQ (App Definition and Development / Streaming & Messaging)
File: Configuration_Client.md

Relative to RocketMQ's Broker cluster, producers and consumers are client. In this section, it mainly describes the common behavior configuration of producers and consumers. ```RocketMQ``` can let client find the ```Name Server```, and then find the ```Broker```by the ```Name Server```. Followings show a variety of configurations, and priority level from highly to lower, the highly priority configurations can override the lower priority configurations. Specified ```Name Server``` address in the code, and multiple ```Name Server``` addresses are separated by semicolons ```java producer.setNamesrvAddr("192.168.0.1:9876;192.168.0.2:9876"); consumer.setNamesrvAddr("192.168.0.1:9876;192.168.0.2:9876"); ``` Specified ```Name Server``` address in the Java setup parameters ```text -Drocketmq.namesrv.addr=192.168.0.1:9876;192.168.0.2:9876 ``` Specified ```Name Server``` address in the environment variables ```text export NAMESRV_ADDR=192.168.0.1:9876;192.168.0.2:9876 ``` HTTP static server addressing(default) After client started, it will access the http static server address, as: <http://jmenv.tbsite.net:8080/rocketmq/nsaddr>, this URL return the following contents: ```text 192.168.0.1:9876;192.168.0.2:9876 ``` By default, the client accesses the HTTP server every 2 minutes, and update the local Name Server address.The URL is hardcoded in the code, you can change the target server by updating ```/etc/hosts``` file, such as add following configuration at the ```/etc/hosts```: ```text 10.232.22.67 jmenv.tbsite.net ``` HTTP static server addressing is recommended, because it is simple client deployment, and the Name Server cluster can be upgraded hot. ```DefaultMQProducer```,```TransactionMQProducer```,```DefaultMQPushConsumer```,```DefaultMQPullConsumer``` all extends the ```ClientConfig``` Class, ```ClientConfig``` as the client common configuration class. Client configuration style like getXXX,setXXX, each of the parameters can config by spring and also config their in the code. Such as the ```namesrvAddr``` parameter: ```producer.setNamesrvAddr("192.168.0.1:9876")```, same with the other parameters. | Parameter Name | Default Value | Description | | -- | - | | | namesrvAddr | | Name Server address list, multiple NameServer addresses are separated by semicolons | | clientIP | local IP | Client local ip address, some machines will fail to recognize the client IP address, which needs to be enforced in the code | | instanceName | DEFAULT | Name of the client instance, Multiple producers and consumers created by the client actually share one internal instance (this instance contains network connection, thread resources, etc.). | | clientCallbackExecutorThreads | 4 | Number of communication layer asynchronous callback threads | | pollNameServerInteval | 30000 | Polling the Name Server interval in milliseconds | | heartbeatBrokerInterval | 30000 | The heartbeat interval, in milliseconds, is sent to the Broker | | persistConsumerOffsetInterval | 5000 | The persistent Consumer consumes the progress interval in milliseconds | | Parameter Name | Default Value | Description | | -- | - | | | producerGroup | DEFAULT_PRODUCER | The name of the Producer

If multiple producers belong to one application and send the same message, they should be grouped into the same group | | createTopicKey | TBW102 | When a message is sent, topics that do not exist on the server are automatically created and a Key is specified that can be used to configure the default route to the topic where the message is sent.| | defaultTopicQueueNums | 4 | The number of default queue when sending messages and auto created topic which not exists the server| | sendMsgTimeout | 3000 | Timeout time of sending message in milliseconds | | compressMsgBodyOverHowmuch | 4096 | The message Body begins to compress beyond the size(the Consumer gets the message automatically unzipped.), unit of byte| | retryAnotherBrokerWhenNotStoreOK | FALSE | If send message and return sendResult but sendStatus!=SEND_OK, Whether to resend | | retryTimesWhenSendFailed | 2 | If send message failed, maximum number of retries, this parameter only works for synchronous send mode| | maxMessageSize | 4MB | Client limit message body size, over it may error. Server also limit so need to work with server | | transactionCheckListener | | The transaction message looks back to the listener, if you want send transaction message, you must setup this | checkThreadPoolMinSize | 1 | Minimum of thread in thread pool when Broker look back Producer transaction status | | checkThreadPoolMaxSize | 1 | Maximum of thread in thread pool when Broker look back Producer transaction status | | checkRequestHoldMax | 2000 | Producer local buffer request queue size when Broker look back Producer transaction status | | RPCHook | null | This parameter is passed in when the Producer is creating, including the pre-processing before the message sending and the processing after the message response. The user can do some security control or other operations in the first interface.| | Parameter Name | Default Value | Description | | - | -- | | | consumerGroup | DEFAULT_CONSUMER | Consumer group

If multi Consumer belong to an application, subscribe the same message and consume logic as the same, they should be gathered together | | messageModel | CLUSTERING | Message support two mode: cluster consumption and broadcast consumption | | consumeFromWhere | CONSUMEFROMLAST_OFFSET | After Consumer started, default consumption from last location, it include two situation: One is last consumption location is not expired, and consumption start at last location; The other is last location expired, start consumption at current queue's first message | | consumeTimestamp | Half an hour ago | Only consumeFromWhere=CONSUMEFROMTIMESTAMP, this can work | | allocateMessageQueueStrategy | AllocateMessageQueueAveragely | Implements strategy of Rebalance algorithms | | subscription | | subscription relation | | messageListener | | message listener | | offsetStore | | Consumption progress store | | consumeThreadMin | 20 | Minimum of thread in consumption thread pool | | consumeThreadMax | 20 | Maximum of thread in consumption thread pool | | | | | | consumeConcurrentlyMaxSpan | 2000 | Maximum span allowed for single queue parallel consumption | | pullThresholdForQueue | 1000 | Pull message local queue cache maximum number of messages | | pullInterval | 0 | Pull message interval, because long polling it is 0, but for flow control, you can set value which greater than 0 in milliseconds | | consumeMessageBatchMaxSize | 1 | Batch consume message | | pullBatchSize | 32 | Batch pull message | | Parameter Name | Default Value | Description | | -- | -- | | | consumerGroup | DEFAULT_CONSUMER | Consumer group name. If multi Consumer belong to an application, subscribe the same message and consume logic as the same, they should be gathered together | | brokerSuspendMaxTimeMillis | 20000 | Long polling, Consumer pull message request suspended for the longest time in the Broker in milliseconds | | consumerTimeoutMillisWhenSuspend | 30000 | Long polling, Consumer pull message request suspend in the Broker over this time value, client think timeout. Unit is milliseconds | | consumerPullTimeoutMillis | 10000 | Not long polling, timeout time of pull message in milliseconds | | messageModel | CLUSTERING | Message support two mode: cluster consumption and broadcast consumption | | messageQueueListener | | Listening changing of queue | | offsetStore | | Consumption schedule store | | registerTopics | | Collection of registered topics | | allocateMessageQueueStrategy | AllocateMessageQueueAveragely | Implements strategy about Rebalance algorithm | | Field Name | Default Value | Description | | -- | | | | Topic | null | Required, the name of the topic to which the message belongs | | Body | null | Required, message body | | Tags | null | Optional, message tag, convenient for server filtering. Currently only one tag per message is supported | | Keys | null | Optional, represent this message's business keys, server create hash indexes based keys. After setting, you can find message by ```Topics```,```Keys``` in Console system. Because of hash indexes, please make key as unique as possible, such as order number, goods Id and so on.| | Flag | 0 | Optional, it is entirely up to the application, and RocketMQ does not intervene | | DelayTimeLevel | 0 | Optional, message delay level, 0 represent no delay, greater tan 0 can consume | | WaitStoreMsgOK | TRUE | Optional, indicates whether the message is not answered until the server is down. |