kafka-node

Producer

Producer(client,[options])

• client:和kafka服务保持连接的client对象
• options:一些关于producer的属性
  
{
// Configuration for when to consider a message as acknowledged, default 1
requireAcks: 1,
// The amount of time in milliseconds to wait for all acks before considered, default 100ms
ackTimeoutMs: 100,
// Partitioner type (default = 0, random = 1, cyclic = 2, keyed = 3), default 0
partitionerType: 2
}


Events

• ready:这个事件被触发，当我们准备好发送消息的时候
• error:发生错误的时候，触发这个事件

send(payloads,cb)

• payloads:是一个数组，元素都是ProducerRequest，ProducerRequest是一个JSON Object 类似与下面的数据
  
{
topic: 'topicName',
messages: ['message body'], // multi messages should be a array, single message can be just a string or a KeyedMessage instance
key: 'theKey', // only needed when using keyed partitioner
partition: 0, // default 0
attributes: 2 // default: 0
}

• cb:是一个回调函数
• attribute 控制着发送消息的压缩方式
  
  • 0:不压缩
  • 1:GZip的方式压缩
  • 2: snappy压缩格式

⚠️一批给同一个topic发送多个消息，要使用messages，否则会丢失信息

createTopics(topics,async,cb)

• 这个方法用来在kafka server上创建新的topics.只有在auto.create.topics.enable是true的时候这个函数才会起作用
• 我们的client发送消息的给server的时候，server会自动创建队列（topics）
• 当async呗设置为false的时候，这个函数不会结束，除非所有的topic都被创建，否则是立即返回。就是是否阻塞的意思
• topics:是一个数组。
• async: 是一个布尔类型的变量
• cb: 函数，回调函数

example:var kafka = require('kafka-node'),    Producer = kafka.Producer,    client = new kafka.Client(),    producer = new Producer(client);// Create topics sync producer.createTopics(['t','t1'], false, function (err, data) {    console.log(data);});// Create topics async producer.createTopics(['t'], true, function (err, data) {});producer.createTopics(['t'], function (err, data) {});// Simply omit 2nd arg 

HighLevelProducer

基本和Producer一样

HighLevelProducer(client,[option])

• client:和Producer类似，client都是和kafka server保持一个连接
• options: 属性关于Producer
  
{
// Configuration for when to consider a message as acknowledged, default 1
requireAcks: 1,
// The amount of time in milliseconds to wait for all acks before considered, default 100ms
ackTimeoutMs: 100,
// Partitioner type (default = 0, random = 1, cyclic = 2, keyed = 3), default 2
partitionerType: 3
}


Events

• ready:被触发当准备好发送消息的时候
• error:发生错误的时候触发

Consumer

Consumer(client,payloads,options)

• client:和上方一样
• payloads:数组，数组的元素类型是FetchRequest，FetchRequest是一个JSON类型的数据，类似如下：
  
{
topic: 'topicName',
offset: 0, //default 0
}

• options:关于consumer的属性设置，例如下：
  
{
groupId: 'kafka-node-group',//consumer group id, default `kafka-node-group`
// Auto commit config
autoCommit: true,
autoCommitIntervalMs: 5000,
// The max wait time is the maximum amount of time in milliseconds to block waiting if insufficient data is available at the time the request is issued, default 100ms
fetchMaxWaitMs: 100,
// This is the minimum number of bytes of messages that must be available to give a response, default 1 byte
fetchMinBytes: 1,
// The maximum bytes to include in the message set for this partition. This helps bound the size of the response.
fetchMaxBytes: 1024 * 1024,
// If set true, consumer will fetch message from the given offset in the payloads
fromOffset: false,
// If set to 'buffer', values will be returned as raw buffer objects.
encoding: 'utf8'
}


example:var kafka = require('kafka-node'),    Consumer = kafka.Consumer,    client = new kafka.Client(),    consumer = new Consumer(        client,        [            { topic: 't', partition: 0 }, { topic: 't1', partition: 1 }        ],        {            autoCommit: false        }    );

on(‘message’,onMessage)

    一般来说，我们会consume最后一个提交的messages从我们的current group中

• onMessage:函数，新消息来的时候的回调函数

example:consumer.on('message', function (message) {    console.log(message);});

addTopics(topics,cb,fromoffset)

添加进来的topics如果不存在，则返回错误

- topics:数组，被添加的topic的数组
- cb:函数，回调函数
- fromOffset:布尔值，如果是真的，consumber将会从特定的位置获取message，否则默认最后一个

removeTopics(topics,cb)

• topics:数组，被移除的topic的数组
• cb:回调函数

Commit(cb)

• cb:回调函数

setOffset(topic,partition,offset)

设定给定topic的offset

- topic:字符串
- partition:数字
- offset:数字

example:consumer.setOffset('topic', 0, 0);

Pause()

暂停consumer，仅仅是暂停consumer，不会影响producer

resume()

恢复consumer，恢复fetch 的这个循环

PauseTopics(topics)

暂停指定的topics

example:consumer.pauseTopics([    'topic1',    { topic: 'topic2', partition: 0 }]);

resumeTopics(topics)

close(force,cb)

• force:布尔类型的值，如果是true，那么她会强制consumer提交现在的offset在关闭之前，默认的是false

example:consumer.close(true, cb);consumer.close(cb); //force is disabled