CanalSharp |中文

master：

Ⅰ.What is CanalSharp

CanalSharp is a .NET Client of alibaba's open source component Canal,and it provides .NET 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:

Database Mirroring
Realtime Database backup
Multi-level index
search build
Busienss cache refresh
Notification on price change(in e-commerce site) and so on

Ⅱ.Using scenarios

CanalSharp as a .NET 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:

As a substitution of polling Database to monitor Database changes,it is much more effective than polling.
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.
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.
Database Backup,synchronization.
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)
Push changed data to RabbitMq,kafak or other message queues for consuming.

Ⅲ.Working mechanism

As a .NET 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

Canal connect to Mysql database ,pretented to be a slave of mysql
CanalSharp(as mentioned it is a client of Cancal) connect to Canal
When data in the database changed,it write the changes to binlog
Canal send dump request to mysql database,get binlog and then parse it.
CancalSharp send request to Canal for data.
Canal send parsed data to CanalSharp
CancalSharp get data successfully and then send an acknowledgement to Canal(optional)
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 .NET Core Console Project

3. Install CanalSharp from Nuget Package source

Install-Package CanalSharp.Client

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

4. Connect to Canal

//canal' destination config,default to example
var destination = "example";
//instantiate a simple CanalClient connector object(it does not support clustering),the parameters are canal's IP Address,port number,destination,username and password
var connector = CanalConnectors.NewSingleConnector("127.0.0.1", 11111, destination, "", "");
//connect to Canal
connector.Connect();
//Subscription,the parameter is a Filter,if we provided nothing it use Canal's default Filter. a filter is a rule for filtering data,data go throgh the filter will be passed in.
connector.Subscribe(".*\\..*");

//Get data with acknowledgement to indicate success
connector.Get(batchSize);
//Get data without acknowledgement to indicate success
connector.GetWithoutAck(batchSize);

for more detailed information please visit Sample

Ⅵ Run CanalSharp via Docker quickly

1. Run mysql and canal by command

git clone https://github.com/CanalSharp/CanalSharp.git
cd  CanalSharp
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 CanalSharp get the changed data.

Ⅶ What we will do next

CanalSharp clustering support

Ⅷ Contribute

We gladly accept community contributions.

1.fork the CanalSharp 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.

mirbeta/CanalSharp