该方案通过扩展在dubbo下扩展出兼容dubbox的DubboxProtocol，从而在dubbo的框架下提供一种兼容dubbox的方案。
详细代码参考：https://github.com/aquariuspj/dubbo-extensions.git
- dubbo与dubbox不兼容的原因
- 解决方案
- 使用说明
- 附录1 dubbo与dubbox协议相互调用的报错信息
- 附录2，DecodeableRpcInvocation.decode()方法源码对比
- 附录3，DubboxCodec.encodeRequestData()方法源码对比
dubbo与dubbox不兼容的原因
测试版本：
| 框架 | 源码地址 | branch/tag | version |
|---|---|---|---|
| dubbox | https://github.com/dangdangdotcom/dubbox | branch:master | 2.8.4 |
| dubbo | https://github.com/apache/dubbo | tag:2.7.7 | 2.7.7 |
经过对两个版本的DecodeableRpcInvocation decode方法进行对比，可以发现二者的主要差异点在于反序列化的元素上【参考《附录2，DecodeableRpcInvocation.decode()方法源码对比》】：
| 框架 | 反序列化顺序 |
|---|---|
| dubbox | 1.dubboVersion; 2.path; 3.version; 4.methodName; 5.desc. |
| dubbo | 1.dubboVersion; 2.path; 3.version; 4.methodName; 5.argNum; 6.argNum<-1时，有desc. |
我们已知两个版本的反序列化顺序，那么可以猜测两个版本的序列化顺序也一定和反序列化保持一致的，通过代码跟踪发现确实如此。【参考《附录3，DubboxCodec.encodeRequestData()方法源码对比》】。
解决方案
- 通过修改dubbox源码，判断dubboVersion执行不同的序列化/反序列化逻辑来兼容dubbo。
- 通过修改dubbo源码，判断dubboVersion执行不同的序列化/反序列化逻辑来兼容dubbox。
- 通过在dubbox和dubbo上同时扩展dubbox协议来相互兼容，同时防止二者的dubbo协议互串。
- 其他。
本项目采用第三种解决方案。
实现思路为：
- 通过Dubbo的SPI机制，先在Dubbo中扩展出兼容Dubbox的DubboxProtocol协议，
- 通过Dubbox的SPI机制，在dubbox中为dubbo协议新增dubbox的别名，从而与(1.)能够相互识别DubboxProtocol。
- 各自在注册中心上暴露基于dubbox协议的服务。
- 相互调用。
使用说明
详细代码可以参考dubbox-protocol-samples项目。
dubbo项目调用dubbox项目
-
在dubbox中扩展dubbox协议： 在dubbox项目中的resource/META-INF/dubbo目录下新建com.alibaba.dubbo.rpc.Protocol文件，并填入内容
dubbox=com.alibaba.dubbo.rpc.protocol.dubbo.DubboProtocol; -
在dubbo中扩展dubbox协议： 已发布到Maven中央仓库，可以直接引入。
<dependency> <groupId>cn.luckyee.dubbo</groupId> <artifactId>dubbox-protocol-all</artifactId> <version>1.1-RELEASE</version> </dependency> -
将原dubbox项目中的服务注册为dubbox协议 （注意，zkgroup一定要分开，否则dubbox项目的dubbo协议会被dubbo项目误认为dubbo协议从而导致调用失败）
<dubbo:registry id="zk01" address="zookeeper://127.0.0.1:2181" group="zkg01" /> <dubbo:registry id="zk02" address="zookeeper://127.0.0.1:2181" group="zkg02" /> <dubbo:protocol name="dubbo" port="20890" default="false" /> <dubbo:protocol name="dubbox" port="20891" default="false" /> <dubbo:service interface="cn.luckyee.dubbox.protocol.samples.api.DubboxProtocolDemoService" ref="dubboxProtocolDemoService" registry="zk01" protocol="dubbo" version="1.0.0" /> <dubbo:service interface="cn.luckyee.dubbox.protocol.samples.api.DubboxProtocolDemoService" ref="dubboxProtocolDemoService" registry="zk02" protocol="dubbox" version="1.0.0" /> -
将dubbo项目中的consumer配置到同一个group引入该dubbox服务
配置文件
dubbo.registries.zk01.address=zookeeper://127.0.0.1:2181 dubbo.registries.zk01.group=zkg01 dubbo.registries.zk02.address=zookeeper://127.0.0.1:2181 dubbo.registries.zk02.group=zkg02 dubbo.protocols.dubbox.name=dubbox dubbo.protocols.dubbo.name=dubbo引入服务
@DubboReference(registry = {"zk02"}, version = "1.0.0", check = false) DubboxProtocolDemoService dubboxProtocolDemoService;
dubbox项目调用dubbo项目
-
在dubbox中扩展dubbox协议： 在dubbox项目中的resource/META-INF/dubbo目录下新建com.alibaba.dubbo.rpc.Protocol文件，并填入内容
dubbox=com.alibaba.dubbo.rpc.protocol.dubbo.DubboProtocol; -
在dubbo中扩展dubbox协议： 已发布到Maven中央仓库，可以直接引入。
<dependency> <groupId>cn.luckyee.dubbo</groupId> <artifactId>dubbox-protocol-all</artifactId> <version>1.1-RELEASE</version> </dependency> -
将原dubbo项目中的服务注册为dubbox协议
假设原始服务如下：
@Service @DubboService(registry = "zk01", protocol = "dubbo", version = "1.0.0") public class DubboProtocolDemoServiceImpl implements DubboProtocolDemoService { …… }建议新增包装接口与实现类：
@DubboService(registry = "zk02", protocol = "dubbox", version = "1.0.0") public class DubboProtocolDemoServiceImpl2 implements DubboProtocolDemoService2 { // 此处是暴露在zk01的dubbo协议的原服务 @Autowired DubboProtocolDemoServiceImpl dubboProtocolDemoService; @Override public String service(String req1, String req2) { return dubboProtocolDemoService.service(req1, req2); } }配置文件
dubbo.protocols.dubbo.name=dubbo dubbo.protocols.dubbo.port=20892 dubbo.protocols.dubbox.name=dubbox dubbo.protocols.dubbox.port=20893 dubbo.registries.zk01.address=zookeeper://127.0.0.1:2181 dubbo.registries.zk01.group=zkg01 dubbo.registries.zk02.address=zookeeper://127.0.0.1:2181 dubbo.registries.zk02.group=zkg02 -
将dubbox项目中的consumer配置到同一个group并引入该dubbo服务
<dubbo:registry id="zk01" address="zookeeper://127.0.0.1:2181" group="zkg01" default="false"/> <dubbo:registry id="zk02" address="zookeeper://127.0.0.1:2181" group="zkg02" default="false"/> <dubbo:protocol name="dubbox" /> <dubbo:protocol name="dubbo" /> <dubbo:reference id="dubboxProtocolDemoService" interface="cn.luckyee.dubbox.protocol.samples.api.DubboxProtocolDemoService" protocol="dubbo" registry="zk01" check="false" version="1.0.0" /> <dubbo:reference id="dubboProtocolDemoService2" interface="cn.luckyee.dubbox.protocol.samples.api.DubboProtocolDemoService2" protocol="dubbox" registry="zk02" check="false" version="1.0.0" />
经过上述配置，dubbo项目能够通过dubbox协议与dubbox项目互通。
附录1 dubbo与dubbox协议相互调用的报错信息
1. dubbo consumer 调用 dubbox provider.
dubbo consumer错误信息
Exception in thread "main" org.apache.dubbo.rpc.RpcException: Failed to invoke the method service in the service cn.luckyee.demo.dubbo.api.S000001. Tried 3 times of the providers [192.168.1.4:20890] (1/2) from the registry 127.0.0.1:2181 on the consumer 192.168.1.4 using the dubbo version 2.7.7. Last error is: Failed to invoke remote method: service, provider: dubbo://192.168.1.4:20890/cn.luckyee.demo.dubbo.api.S000001?anyhost=true&application=dubbo-client&check=false&default=false&dubbo=2.8.4&generic=false&init=false&interface=cn.luckyee.demo.dubbo.api.S000001&methods=service&pid=23144&qos.enable=false®ister.ip=192.168.1.4&remote.application=dubbox-server&revision=1.0.0&side=consumer&sticky=false×tamp=1593945022144&version=1.0.0, cause: org.apache.dubbo.remoting.RemotingException: Fail to decode request due to: RpcInvocation [……]
at org.apache.dubbo.rpc.cluster.support.FailoverClusterInvoker.doInvoke(FailoverClusterInvoker.java:113)
at org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker.invoke(AbstractClusterInvoker.java:259)
at org.apache.dubbo.rpc.cluster.interceptor.ClusterInterceptor.intercept(ClusterInterceptor.java:47)
at org.apache.dubbo.rpc.cluster.support.wrapper.AbstractCluster$InterceptorInvokerNode.invoke(AbstractCluster.java:92)
at org.apache.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.invoke(MockClusterInvoker.java:82)
at org.apache.dubbo.rpc.proxy.InvokerInvocationHandler.invoke(InvokerInvocationHandler.java:74)
at org.apache.dubbo.common.bytecode.proxy0.service(proxy0.java)
……
dubbox provider错误信息
com.alibaba.com.caucho.hessian.io.HessianProtocolException: expected integer at 0x12 java.lang.String (Ljava/lang/Object;)
at com.alibaba.com.caucho.hessian.io.Hessian2Input.error(Hessian2Input.java:2720)
at com.alibaba.com.caucho.hessian.io.Hessian2Input.expect(Hessian2Input.java:2691)
at com.alibaba.com.caucho.hessian.io.Hessian2Input.readInt(Hessian2Input.java:773)
at com.alibaba.dubbo.common.serialize.support.hessian.Hessian2ObjectInput.readInt(Hessian2ObjectInput.java:58)
at com.alibaba.dubbo.rpc.protocol.dubbo.DecodeableRpcInvocation.decode(DecodeableRpcInvocation.java:106)
at com.alibaba.dubbo.rpc.protocol.dubbo.DecodeableRpcInvocation.decode(DecodeableRpcInvocation.java:74)
at com.alibaba.dubbo.rpc.protocol.dubbo.DubboCodec.decodeBody(DubboCodec.java:138)
at com.alibaba.dubbo.remoting.exchange.codec.ExchangeCodec.decode(ExchangeCodec.java:134)
at com.alibaba.dubbo.remoting.exchange.codec.ExchangeCodec.decode(ExchangeCodec.java:95)
at com.alibaba.dubbo.rpc.protocol.dubbo.DubboCountCodec.decode(DubboCountCodec.java:46)
……
dubbox consumer 调用 duubo provider.
dubbo provider和dubbox consumer错误信息一样，说明provider将错误信息返回给了consumer。
java.lang.IllegalArgumentException: Service not found: ……
at org.apache.dubbo.rpc.protocol.dubbo.DecodeableRpcInvocation.decode(DecodeableRpcInvocation.java:134) ~[dubbo-2.7.7.jar:2.7.7]
at org.apache.dubbo.rpc.protocol.dubbo.DecodeableRpcInvocation.decode(DecodeableRpcInvocation.java:80) ~[dubbo-2.7.7.jar:2.7.7]
at org.apache.dubbo.remoting.transport.DecodeHandler.decode(DecodeHandler.java:57) [dubbo-2.7.7.jar:2.7.7]
at org.apache.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:44) [dubbo-2.7.7.jar:2.7.7]
……
附录2，DecodeableRpcInvocation.decode()方法源码对比
dubbo DecodeableRpcInvocation
@Override
public Object decode(Channel channel, InputStream input) throws IOException {
……
String dubboVersion = in.readUTF();
……
String path = in.readUTF();
……
setAttachment(VERSION_KEY, in.readUTF());
setMethodName(in.readUTF());
String desc = in.readUTF();
……
args[i] = in.readObject(pts[i]);
……
Map<String, Object> map = in.readAttachments();
……
return this;
}
dubbox DecodeableRpcInvocation
public Object decode(Channel channel, InputStream input) throws IOException {
……
setAttachment(Constants.DUBBO_VERSION_KEY, in.readUTF());
setAttachment(Constants.PATH_KEY, in.readUTF());
setAttachment(Constants.VERSION_KEY, in.readUTF());
setMethodName(in.readUTF());
……
int argNum = in.readInt();
if (argNum >= 0) {
……
args[i] = in.readObject();
……
} else {
String desc = in.readUTF();
……
args[i] = in.readObject(pts[i]);
……
}
Map<String, String> map = (Map<String, String>) in.readObject(Map.class);
……
return this;
}
附录3，DubboxCodec.encodeRequestData()方法源码对比
dubbo DubboxCodec
@Override
protected void encodeRequestData(Channel channel, ObjectOutput out, Object data, String version) throws IOException {
RpcInvocation inv = (RpcInvocation) data;
out.writeUTF(version);
// https://github.com/apache/dubbo/issues/6138
String serviceName = inv.getAttachment(INTERFACE_KEY);
if (serviceName == null) {
serviceName = inv.getAttachment(PATH_KEY);
}
out.writeUTF(serviceName);
out.writeUTF(inv.getAttachment(VERSION_KEY));
out.writeUTF(inv.getMethodName());
out.writeUTF(inv.getParameterTypesDesc());
Object[] args = inv.getArguments();
if (args != null) {
for (int i = 0; i < args.length; i++) {
out.writeObject(encodeInvocationArgument(channel, inv, i));
}
}
out.writeAttachments(inv.getObjectAttachments());
}
dubbox DubboxCodec
@Override
protected void encodeRequestData(Channel channel, ObjectOutput out, Object data) throws IOException {
RpcInvocation inv = (RpcInvocation) data;
out.writeUTF(inv.getAttachment(Constants.DUBBO_VERSION_KEY, DUBBO_VERSION));
out.writeUTF(inv.getAttachment(Constants.PATH_KEY));
out.writeUTF(inv.getAttachment(Constants.VERSION_KEY));
out.writeUTF(inv.getMethodName());
// NOTICE modified by lishen
// TODO
if (getSerialization(channel) instanceof OptimizedSerialization && !containComplexArguments(inv)) {
out.writeInt(inv.getParameterTypes().length);
} else {
out.writeInt(-1);
out.writeUTF(ReflectUtils.getDesc(inv.getParameterTypes()));
}
Object[] args = inv.getArguments();
if (args != null)
for (int i = 0; i < args.length; i++){
out.writeObject(encodeInvocationArgument(channel, inv, i));
}
out.writeObject(inv.getAttachments());
}
如有任何问题，欢迎交流指教。
首发于 https://www.cnblogs.com/prpl 和 https://xyz.luckyee.xyz:55543/ ，未经许可不允许转载，谢谢合作。