Protocol
Dubbo has implemented a lot of built-in functionalities through protocol extensions and also supports many commonly used protocols. You can see all custom protocols in the org.apache.dubbo.rpc.Protocol file. For example, in Dubbo 3, we have:
# Built-in functionalities implemented by Dubbo through protocol extension
filter=org.apache.dubbo.rpc.cluster.filter.ProtocolFilterWrapper
qos=org.apache.dubbo.qos.protocol.QosProtocolWrapper
registry=org.apache.dubbo.registry.integration.InterfaceCompatibleRegistryProtocol
service-discovery-registry=org.apache.dubbo.registry.integration.RegistryProtocol
listener=org.apache.dubbo.rpc.protocol.ProtocolListenerWrapper
mock=org.apache.dubbo.rpc.support.MockProtocol
serializationwrapper=org.apache.dubbo.rpc.protocol.ProtocolSerializationWrapper
securitywrapper=org.apache.dubbo.rpc.protocol.ProtocolSecurityWrapper
# Commonly used protocols supported by Dubbo
dubbo=org.apache.dubbo.rpc.protocol.dubbo.DubboProtocol
injvm=org.apache.dubbo.rpc.protocol.injvm.InjvmProtocol
rest=org.apache.dubbo.rpc.protocol.rest.RestProtocol
grpc=org.apache.dubbo.rpc.protocol.grpc.GrpcProtocol
tri=org.apache.dubbo.rpc.protocol.tri.TripleProtocol
As you can see, Dubbo has implemented a series of functionalities like filtering, monitoring, service discovery, listeners, mock, serialization, and security through protocol extensions. It also supports dubbo, injvm, rest, grpc, and tri protocols for external use.
There are two ways to customize a private protocol. The first is to wrap an existing protocol and add some specific business logic. The other is to fully customize a new protocol. The former is simpler and has extensive usage in Dubbo, like ProtocolFilterWrapper, QosProtocolWrapper, ProtocolListenerWrapper, etc. The latter is more complex, but Dubbo has implemented most of the commonly used protocols which are well-tested in production environments.
This article will demonstrate how to implement a custom protocol based on an existing protocol.
Prerequisites
Two deployment and running methods, choose one
Based on Kubernetes
Install Kubernetes environment
Modify the configuration file in Provider to enable the address of nacos deployed in Kubernetes
# Specify the application name of Dubbo dubbo.application.name=extensibility-protocol-provider # Enable token verification for each invocation dubbo.provider.token=true # Specify the registry address # dubbo.registry.address=nacos://localhost:8848?username=nacos&password=nacos dubbo.registry.address=nacos://${nacos.address:localhost}:8848?username=nacos&password=nacos # Custom protocol edubbo dubbo.provider.protocol=edubboModify the configuration file in Consumer to enable the address of nacos deployed in Kubernetes
# Specify the application name of Dubbo dubbo.application.name=extensibility-protocol-consumer # Enable token verification for each invocation dubbo.provider.token=true # Specify the registry address # dubbo.registry.address=nacos://localhost:8848?username=nacos&password=nacos dubbo.registry.address=nacos://${nacos.address:localhost}:8848?username=nacos&password=nacos # Custom protocol edubbo dubbo.consumer.protocol=edubboDeploy
[Extensibility Protocol Task](https://github.com/apache/dubbo-samples/blob/master/10-task/dubbo-samples-extensibility/deploy/All.yml)
Using Local IDE
- Deploy Nacos version 2.2.0
- Modify the configuration file in Provider to enable the local nacos address
# Specify the application name of Dubbo dubbo.application.name=extensibility-protocol-provider # Enable token verification for each invocation dubbo.provider.token=true # Specify the registry address # Enable local nacos address dubbo.registry.address=nacos://localhost:8848?username=nacos&password=nacos # Custom protocol edubbo dubbo.provider.protocol=edubbo - Modify the configuration file in Consumer to enable the local nacos address
# Specify the application name of Dubbo dubbo.application.name=extensibility-protocol-consumer # Enable token verification for each invocation dubbo.provider.token=true # Specify the registry address # Enable local nacos address dubbo.registry.address=nacos://localhost:8848?username=nacos&password=nacos # Custom protocol edubbo dubbo.consumer.protocol=edubbo
Task Details
Implement a custom protocol edubbo based on the existing dubbo protocol.
Implementation Method
Wrap the existing dubbo protocol to implement the edubbo protocol.
Code Structure
Common
src
|-main
|-java
|-org
|-apache
|-dubbo
|-samples
|-extensibility
|-protocol
|-common
|-EnhancedProtocol.java (Implement Protocol interface)
Provider
src
|-main
|-java
|-org
|-apache
|-dubbo
|-samples
|-extensibility
|-protocol
|-provider
|-ExtensibilityProtocolProviderApplication.java
|-ExtensibilityProtocolServiceImpl.java
|-resources
|-META-INF
|-application.properties (Dubbo Provider configuration file)
|-dubbo
|-org.apache.dubbo.rpc.Protocol (Plain text file)
Consumer
src
|-main
|-java
|-org
|-apache
|-dubbo
|-samples
|-extensibility
|-protocol
|-consumer
|-ExtensibilityProtocolConsumerApplication.java
|-ExtensibilityProtocolConsumerTask.java
|-resources
|-META-INF
|-application.properties (Dubbo Consumer configuration file)
|-dubbo
|-org.apache.dubbo.rpc.Protocol (
Plain text file)
Code Details
package org.apache.dubbo.samples.extensibility.protocol.common;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.rpc.Protocol;
import org.apache.dubbo.rpc.Invoker;
import org.apache.dubbo.rpc.Exporter;
import org.apache.dubbo.rpc.ProtocolServer;
import org.apache.dubbo.rpc.RpcException;
import org.apache.dubbo.rpc.model.FrameworkModel;
import org.apache.dubbo.rpc.protocol.dubbo.DubboProtocol;
import java.util.List;
public class EnhancedProtocol implements Protocol {
public EnhancedProtocol(FrameworkModel frameworkModel) {
this.protocol = new DubboProtocol(frameworkModel);
}
private final Protocol protocol;
@Override
public int getDefaultPort() {
return this.protocol.getDefaultPort();
}
@Override
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
// do something
return this.protocol.export(invoker);
}
@Override
public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {
// do something
return this.protocol.refer(type, url);
}
@Override
public void destroy() {
this.protocol.destroy();
}
@Override
public List<ProtocolServer> getServers() {
return protocol.getServers();
}
}
SPI Configuration
Provider
Add the following configuration to the resources/META-INF/dubbo/org.apache.dubbo.rpc.Protocol file:
edubbo=org.apache.dubbo.samples.extensibility.protocol.common.EnhancedProtocol
Consumer
Add the following configuration to the resources/META-INF/dubbo/org.apache.dubbo.rpc.Protocol file:
edubbo=org.apache.dubbo.samples.extensibility.protocol.common.EnhancedProtocol
Configuration File
Provider
Add the following configuration to the resources/application.properties file:
# Custom protocol
dubbo.provider.protocol=edubbo
Consumer
Add the following configuration to the resources/application.properties file:
# Custom protocol
dubbo.consumer.protocol=edubbo
Execution Results
Run the task using the Using Local IDE method, and the results are as follows:
Register Protocol
Output Result
In summary, Dubbo provides a powerful and flexible protocol extension mechanism. This tutorial demonstrates how to create a custom protocol edubbo based on the existing dubbo protocol, which allows users to add custom logic without changing the underlying architecture.