canal-go |中文

Ⅰ.What is canal-go

canal-go is a golang Client of alibaba's open source component Canal,and it provides golang developer a much easier way to use Canal.

Cancal is a incremental Publish&Subscription component based on mysql's binlog.To learn more a bout Cancal,please visit https://github.com/alibaba/canal/wiki

log based incremental pub&sub model can be applied to many business cases:

1. Database Mirroring
2. Realtime Database backup
3. Multi-level index
4. search build
5. Busienss cache refresh
6. Notification on price change(in e-commerce site) and so on

Ⅱ.Using scenarios

canal-go as a golang client of canal,it can be used in situations where Canal is being used.We have listed some using scenarios above,here are some more detailed use cases:

1. As a substitution of polling Database to monitor Database changes,it is much more effective than polling.

2. Realtime Update data in search engine when data in mysql database changed.For example,in a E-commerce site,when Product information changed,it can be updated to Elasticsearch、solr,etc in a realtime way.

3. Realtime update data in cache,Also take E-commerce site as an example,when price,inventory and other product information changed,it can be updated to Redis in a realtime way.

4. Database Backup,synchronization.

5. To trigger some other business logics on data change,for example,when a customer place an order without payment in a certain period of time and so the order is cancelled automatically,we get the changed status of the order and then we can push a notification to the customer(or take some other actions)

6. Push changed data to RabbitMq,kafak or other message queues for consuming.

Ⅲ.Working mechanism

As a golang client of Canal,it use Socket for communication,the transfer Protocol is TCP,and the data exchange Protocol is Google's Protocol Buffer 3.0

Ⅳ.Workflow

1. Canal connect to Mysql database ,pretented to be a slave of mysql

2. canal-go(as mentioned it is a client of Cancal) connect to Canal

3. When data in the database changed,it write the changes to binlog

4. Canal send dump request to mysql database,get binlog and then parse it.

5. canal-go send request to Canal for data.

6. Canal send parsed data to canal-go

7. canal-go get data successfully and then send an acknowledgement to Canal(optional)

8. Canal record the consumption position

The following picture shows how it works:

Ⅴ.Quick Start

1. Install Canal

To Install and configure Canal,please visit https://github.com/alibaba/canal/wiki/QuickStart for information

2.Create a golang Console Project

3. Install go get from github source

go get  github.com/CanalSharp/canal-go

or you can install it from nuget manager(a graphic ui) in visual studio

4. Connect to Canal

connector := client.NewSimpleCanalConnector("192.168.199.17", 11111, "", "", "example", 60000, 60*60*1000)
	err :=connector.Connect()
	if err != nil {
		log.Println(err)
		os.Exit(1)
	}
	err = connector.Subscribe(".*\\\\..*")
	if err != nil {
		log.Println(err)
		os.Exit(1)
	}

	for {

		message,err := connector.Get(100, nil, nil)
		if err != nil {
			log.Println(err)
			os.Exit(1)
		}
		batchId := message.Id
		if batchId == -1 || len(message.Entries) <= 0 {
			time.Sleep(300 * time.Millisecond)
			fmt.Println("===没有数据了===")
			continue
		}

		printEntry(message.Entries)

	}

for more detailed information please visit Sample

Ⅵ Run canal-go via Docker quickly

1. Run mysql and canal by command

git clone https://github.com/CanalClient/canal-go.git
cd canal-go
cd docker
docker-compose up -d

2. Use navicat or orther client to connect to mysql

ip：the ip address of the server where docker running

mysql username：root

mysql password：000000

mysql port：4406

There is a default database named test,which contains a table named test

3.run the sample project

4.Test it

Execute the following sql:

insert into test values(1000,'111');
update test set name='222' where id=1000;
delete from test where id=1000;

we can see that after executing insrt,update,delete sql,Our canal-go get the changed data.

Ⅶ What we will do next

canal-go clustering support

Ⅷ Contribute

We gladly accept community contributions.

1.fork the canal-go Project

2.make changes to it

3.make a pull request

Please do not hesitate to make a pull request,your effort will not in vain.