Protocol
org.apache.dubbo.rpc.Protocol SPI.In the Communication Protocol chapter, we learned about several core RPC protocols built into Dubbo: dubbo, rest, and tri, and how to use them. This article explains how to provide a custom RPC protocol implementation by extending the org.apache.dubbo.rpc.Protocol SPI.
There are two ways to create a private protocol: the first is to wrap the existing protocol and add specific business logic. The second is to completely customize a protocol. The former is simpler to implement and is widely used in dubbo, such as ProtocolFilterWrapper, QosProtocolWrapper, and ProtocolListenerWrapper. The latter is relatively complex but offers maximum flexibility; for instance, the built-in protocols dubbo and triple in the Dubbo framework fall under this implementation style.
For the complete source code of this example, refer to dubbo-samples-extensibility. In addition to this example, many Protocol implementations in the core Dubbo repository apache/dubbo and the extension library apache/dubbo-spi-extensions can also serve as extension references:
# Common protocols supported by Dubbo
dubbo=org.apache.dubbo.rpc.protocol.dubbo.DubboProtocol
tri=org.apache.dubbo.rpc.protocol.tri.TripleProtocol
Task Details
Implement a custom protocol edubbo based on the existing dubbo protocol.
Implementation
The edubbo protocol is implemented by wrapping the dubbo protocol.
Code Structure
Common
src
|-main
|-java
|-org
|-apache
|-dubbo
|-samples
|-extensibility
|-protocol
|-common
|-EnhancedProtocol.java (Implements 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 in 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 in 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 in the resources/application.properties file:
# Custom protocol
dubbo.provider.protocol=edubbo
Consumer
Add the following configuration in the resources/application.properties file:
# Custom protocol
dubbo.consumer.protocol=edubbo
Run Results
Run the task using local IDE, the results are as follows:
Registered Protocol
Output Result
