Kafka-node
Kafka-node is a Node.js client with Zookeeper integration for Apache Kafka. It only supports the latest version of Kafka 0.8 which is still under development, so this module is not production ready so far.
The Zookeeper integration does the following jobs:
- Loads broker metadata from Zookeeper before we can communicate with the Kafka server
- Watches broker state, if broker changes, the client will refresh broker and topic metadata stored in the client
Install Kafka
Follow the instructions on the Kafka wiki to build Kafka 0.8 and get a test broker up and running.
API
Client
Client(connectionString, clientId, [zkOptions])
connectionString
: Zookeeper connection string, defaultlocalhost:2181/
clientId
: This is a user-supplied identifier for the client application, defaultkafka-node-client
zkOptions
: Object, Zookeeper options, see node-zookeeper-client
close(cb)
Closes the connection to Zookeeper and the brokers so that the node process can exit gracefully.
cb
: Function, the callback
Producer
Producer(client)
client
: client which keeps a connection with the Kafka server.
var kafka = require('kafka-node'),
Producer = kafka.Producer,
client = new kafka.Client(),
producer = new Producer(client);
send(payloads, cb)
payloads
: Array,array ofProduceRequest
,ProduceRequest
is a JSON object like:
{
topic: 'topicName',
messages: ['message body'],// multi messages should be a array, single message can be just a string
partition: 0, //default 0
attributes: 2, // default: 0
}
cb
: Function, the callback
attributes
controls compression of the message set. It supports the following values:
0
: No compression1
: Compress using GZip2
: Compress using snappy
Example:
var kafka = require('kafka-node'),
Producer = kafka.Producer,
client = new kafka.Client(),
producer = new Producer(client),
payloads = [
{ topic: 'topic1', messages: 'hi', partition: 0 },
{ topic: 'topic2', messages: ['hello', 'world'] }
];
producer.on('ready', function () {
producer.send(payloads, function (err, data) {
console.log(data);
});
});
producer.on('error', function (err) {})
createTopics(topics, async, cb)
This method is used to create topics on the Kafka server. It only work when auto.create.topics.enable
, on the Kafka server, is set to true. Our client simply sends a metadata request to the server which will auto create topics. When async
is set to false, this method does not return until all topics are created, otherwise it returns immediately.
topics
: Array, array of topicsasync
: Boolean, async or synccb
: Function, the callback
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
HighLevelProducer(client)
client
: client which keeps a connection with the Kafka server. Round-robins produce requests to the available topic partitions
var kafka = require('kafka-node'),
HighLevelProducer = kafka.HighLevelProducer,
client = new kafka.Client(),
producer = new HighLevelProducer(client);
send(payloads, cb)
payloads
: Array,array ofProduceRequest
,ProduceRequest
is a JSON object like:
{
topic: 'topicName',
messages: ['message body'],// multi messages should be a array, single message can be just a string
attributes: 1
}
cb
: Function, the callback
Example:
var kafka = require('kafka-node'),
HighLevelProducer = kafka.HighLevelProducer,
client = new kafka.Client(),
producer = new HighLevelProducer(client),
payloads = [
{ topic: 'topic1', messages: 'hi' },
{ topic: 'topic2', messages: ['hello', 'world'] }
];
producer.on('ready', function () {
producer.send(payloads, function (err, data) {
console.log(data);
});
});
createTopics(topics, async, cb)
This method is used to create topics on the Kafka server. It only work when auto.create.topics.enable
, on the Kafka server, is set to true. Our client simply sends a metadata request to the server which will auto create topics. When async
is set to false, this method does not return until all topics are created, otherwise it returns immediately.
topics
: Array,array of topicsasync
: Boolean,async or synccb
: Function,the callback
Example:
var kafka = require('kafka-node'),
HighLevelProducer = kafka.HighLevelProducer,
client = new kafka.Client(),
producer = new HighLevelProducer(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
Consumer
Consumer(client, payloads, options)
client
: client which keeps a connection with the Kafka server. Note: it's recommend that create new client for different consumers.payloads
: Array,array ofFetchRequest
,FetchRequest
is a JSON object like:
{
topic: 'topicName',
offset: 0, //default 0
}
options
: options for consumer,
{
groupId: 'kafka-node-group',//consumer group id, deafult `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 * 10,
// 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);
By default, we will consume messages from the last committed offset of the current group
onMessage
: Function, callback when new message comes
Example:
consumer.on('message', function (message) {
console.log(message);
});
on('error', function (err) {})
on('offsetOutOfRange', function (err) {})
addTopics(topics, cb, fromOffset)
Add topics to current consumer, if any topic to be added not exists, return error
topics
: Array, array of topics to addcb
: Function,the callbackfromOffset
: Boolean, if true, the consumer will fetch message from the specified offset, otherwise it will fetch message from the last commited offset of the topic.
Example:
consumer.addTopics(['t1', 't2'], function (err, added) {
});
or
consumer.addTopics([{ topic: 't1', offset: 10 }], function (err, added) {
}, true);
removeTopics(topics, cb)
topics
: Array, array of topics to removecb
: Function, the callback
Example:
consumer.removeTopics(['t1', 't2'], function (err, removed) {
});
commit(cb)
Commit offset of the current topics manually, this method should be called when a consumer leaves
cb
: Function, the callback
Example:
consumer.commit(function(err, data) {
});
setOffset(topic, partition, offset)
Set offset of the given topic
-
topic
: String -
partition
: Number -
offset
: Number
Example:
consumer.setOffset('topic', 0, 0);
pause()
Pause the consumer
resume()
Resume the consumer
pauseTopics(topics)
Pause specify topics
consumer.pauseTopics([
'topic1',
{ topic: 'topic2', partition: 0 }
]);
resumeTopics(topics)
Resume specify topics
consumer.resumeTopics([
'topic1',
{ topic: 'topic2', partition: 0 }
]);
close(force, cb)
force
: Boolean, if set to true, it forces the consumer to commit the current offset before closing, defaultfalse
Example
consumer.close(true, cb);
consumer.close(cb); //force is disabled
HighLevelConsumer
HighLevelConsumer(client, payloads, options)
client
: client which keeps a connection with the Kafka server.payloads
: Array,array ofFetchRequest
,FetchRequest
is a JSON object like:
{
topic: 'topicName'
}
options
: options for consumer,
{
groupId: 'kafka-node-group',//consumer group id, deafult `kafka-node-group`
// Auto commit config
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 * 10,
// 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'),
HighLevelConsumer = kafka.HighLevelConsumer,
client = new kafka.Client(),
consumer = new HighLevelConsumer(
client,
[
{ topic: 't' }, { topic: 't1' }
],
{
groupId: 'my-group'
}
);
on('message', onMessage);
By default, we will consume messages from the last committed offset of the current group
onMessage
: Function, callback when new message comes
Example:
consumer.on('message', function (message) {
console.log(message);
});
on('error', function (err) {})
on('offsetOutOfRange', function (err) {})
addTopics(topics, cb, fromOffset)
Add topics to current consumer, if any topic to be added not exists, return error
topics
: Array, array of topics to addcb
: Function,the callbackfromOffset
: Boolean, if true, the consumer will fetch message from the specified offset, otherwise it will fetch message from the last commited offset of the topic.
Example:
consumer.addTopics(['t1', 't2'], function (err, added) {
});
or
consumer.addTopics([{ topic: 't1', offset: 10 }], function (err, added) {
}, true);
removeTopics(topics, cb)
topics
: Array, array of topics to removecb
: Function, the callback
Example:
consumer.removeTopics(['t1', 't2'], function (err, removed) {
});
commit(cb)
Commit offset of the current topics manually, this method should be called when a consumer leaves
cb
: Function, the callback
Example:
consumer.commit(function(err, data) {
});
setOffset(topic, partition, offset)
Set offset of the given topic
-
topic
: String -
partition
: Number -
offset
: Number
Example:
consumer.setOffset('topic', 0, 0);
pause()
Pause the consumer
resume()
Resume the consumer
close(force, cb)
force
: Boolean, if set to true, it forces the consumer to commit the current offset before closing, defaultfalse
Example:
consumer.close(true, cb);
consumer.close(cb); //force is disabled
Offset
Offset(client)
client
: client which keeps a connection with the Kafka server.
events
ready
: when zookeeper is readyconnect
when broker is ready
fetch(payloads, cb)
Fetch the available offset of a specify topic-partition
payloads
: Array,array ofOffsetRequest
,OffsetRequest
is a JSON object like:
{
topic: 'topicName',
partition: 0, //default 0
// time:
// Used to ask for all messages before a certain time (ms), default Date.now(),
// Specify -1 to receive the latest offsets and -2 to receive the earliest available offset.
time: Date.now(),
maxNum: 1 //default 1
}
cb
: Function, the callback
Example
var kafka = require('kafka-node'),
client = new kafka.Client(),
offset = new kafka.Offset(client);
offset.fetch([
{ topic: 't', partition: 0, time: Date.now(), maxNum: 1 }
], function (err, data) {
// data
// { 't': { '0': [999] } }
});
commit(groupId, payloads, cb)
groupId
: consumer grouppayloads
: Array,array ofOffsetCommitRequest
,OffsetCommitRequest
is a JSON object like:
{
topic: 'topicName',
partition: 0, //default 0
offset: 1,
metadata: 'm', //default 'm'
}
Example
var kafka = require('kafka-node'),
client = new kafka.Client(),
offset = new kafka.Offset(client);
offset.commit('groupId', [
{ topic: 't', partition: 0, offset: 10 }
], function (err, data) {
});
fetchCommits(groupid, payloads, cb)
Fetch the last committed offset in a topic of a specific consumer group
groupId
: consumer grouppayloads
: Array,array ofOffsetFetchRequest
,OffsetFetchRequest
is a JSON object like:
{
topic: 'topicName',
partition: 0 //default 0
}
Example
var kafka = require('kafka-node'),
client = new kafka.Client(),
offset = new kafka.Offset(client);
offset.fetchCommits('groupId', [
{ topic: 't', partition: 0 }
], function (err, data) {
});
Todo
- Compression: gzip & snappy (√)
LICENSE - "MIT"
Copyright (c) 2013 Sohu.com
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.