Registry Center, Service Discovery, and Load Balancing on Apache Dubbo

Multicast

Mon, 01 Jan 0001 00:00:00 +0000

The Multicast registry center does not require starting any central node; as long as the broadcast addresses are the same, they can discover each other.

1 Usage Instructions

<dubbo:registry address="multicast://224.5.6.7:1234" />

<dubbo:registry protocol="multicast" address="224.5.6.7:1234" />

Note:

To reduce broadcast volume, Dubbo defaults to sending provider address information to consumers via unicast. If multiple consumer processes are started on one machine, the consumer must declare unicast=false, otherwise only one consumer will receive the message; when the provider and consumer run on the same machine, the consumer also needs to declare unicast=false, otherwise the consumer cannot receive messages, leading to the No provider available for the service exception:

Consul

Mon, 01 Jan 0001 00:00:00 +0000

Prerequisites

Understand Dubbo basic development steps
Install and start the Consul service

Instructions

Add Dependencies

Starting from Dubbo 3, the Consul registration center adaptation is no longer embedded in Dubbo. It needs to be separately introduced with an independent module.

<dependency>
 <groupId>org.apache.dubbo.extensions</groupId>
 <artifactId>dubbo-registry-consul</artifactId>
 <version>3.3.0</version>
</dependency>

Basic Configuration

<dubbo:registry address="redis://10.20.153.10:6379" />

<dubbo:registry address="redis://10.20.153.10:6379?backup=10.20.153.11:6379,10.20.153.12:6379" />

<dubbo:registry protocol="redis" address="10.20.153.10:6379" />

<dubbo:registry protocol="redis" address="10.20.153.10:6379,10.20.153.11:6379,10.20.153.12:6379" />

Etcd

Mon, 01 Jan 0001 00:00:00 +0000

Prerequisites

Understand basic development steps of Dubbo
Install and start the Etcd service

Instructions

Adding Dependencies

Starting from Dubbo 3, the Etcd registry adapter is no longer embedded in Dubbo and needs to be included as a separate module.

<dependency>
 <groupId>org.apache.dubbo.extensions</groupId>
 <artifactId>dubbo-registry-etcd</artifactId>
 <version>3.3.0</version>
</dependency>

Basic Configuration

<dubbo:registry address="etcd://10.20.153.10:6379" />

<dubbo:registry address="etcd://10.20.153.10:6379?backup=10.20.153.11:6379,10.20.153.12:6379" />

<dubbo:registry protocol="etcd" address="10.20.153.10:6379" />

<dubbo:registry protocol="etcd" address="10.20.153.10:6379,10.20.153.11:6379,10.20.153.12:6379" />

Redis

Mon, 01 Jan 0001 00:00:00 +0000

Prerequisites

Understand Dubbo basic development steps
Install and start the Redis service

Instructions

Add Dependency

Starting from Dubbo3, the Redis registry adaptation is no longer embedded in Dubbo and needs to be separately introduced as an independent module.

<dependency>
 <groupId>org.apache.dubbo.extensions</groupId>
 <artifactId>dubbo-registry-redis</artifactId>
 <version>3.3.0</version>
</dependency>

Basic Configuration

<dubbo:registry address="redis://10.20.153.10:6379" />

<dubbo:registry address="redis://10.20.153.10:6379?backup=10.20.153.11:6379,10.20.153.12:6379" />

<dubbo:registry protocol="redis" address="10.20.153.10:6379" />

<dubbo:registry protocol="redis" address="10.20.153.10:6379,10.20.153.11:6379,10.20.153.12:6379" />

Other Configuration Items

You can set the prefix for the keys in Redis with <dubbo:registry group="dubbo" />, default is dubbo.
You can set the Redis cluster policy with <dubbo:registry cluster="replicate" />, default is failover:
- failover: Only write and read from any one, retry another on failure, data synchronization needs to be configured on the server side.
- replicate: Write to all servers simultaneously from the client, read from one, no synchronization needed on the server side, the registration center cluster increases and so does performance pressure.

Working Principle

The registry is implemented based on Redis [^1].