Is it necessary to set the value of SPI?

• I have searched the issues of this repository and believe that this is not a duplicate.
• I have checked the FAQ of this repository and believe that this is not a duplicate.

Environment

Dubbo version: 2.6.2 Operating System version: win7 Java version: 1.8

Step to reproduce this issue

阅读源码发现，每个代理实现类都会去判断默认实现

public class Protocol$Adaptive implements org.apache.dubbo.rpc.Protocol
{
    public void destroy()
    {
        throw new UnsupportedOperationException(
                "method public abstract void org.apache.dubbo.rpc.Protocol.destroy() of interface org.apache.dubbo.rpc.Protocol is not adaptive method!");
    }

    public int getDefaultPort()
    {
        throw new UnsupportedOperationException(
                "method public abstract int org.apache.dubbo.rpc.Protocol.getDefaultPort() of interface org.apache.dubbo.rpc.Protocol is not adaptive method!");
    }

    public org.apache.dubbo.rpc.Invoker refer(java.lang.Class arg0, org.apache.dubbo.common.URL arg1)
        throws org.apache.dubbo.rpc.RpcException
    {
        if (arg1 == null)
            throw new IllegalArgumentException("url == null");
        org.apache.dubbo.common.URL url = arg1;
        String extName = (url.getProtocol() == null ? "dubbo" : url.getProtocol());
        if (extName == null)
            throw new IllegalStateException("Fail to get extension(org.apache.dubbo.rpc.Protocol) name from url("
                    + url.toString() + ") use keys([protocol])");
        org.apache.dubbo.rpc.Protocol extension = (org.apache.dubbo.rpc.Protocol) ExtensionLoader
                .getExtensionLoader(org.apache.dubbo.rpc.Protocol.class).getExtension(extName);
        return extension.refer(arg0, arg1);
    }

    public org.apache.dubbo.rpc.Exporter export(org.apache.dubbo.rpc.Invoker arg0)
        throws org.apache.dubbo.rpc.RpcException
    {
        if (arg0 == null)
            throw new IllegalArgumentException("org.apache.dubbo.rpc.Invoker argument == null");
        if (arg0.getUrl() == null)
            throw new IllegalArgumentException("org.apache.dubbo.rpc.Invoker argument getUrl() == null");
        org.apache.dubbo.common.URL url = arg0.getUrl();
        String extName = (url.getProtocol() == null ? "dubbo" : url.getProtocol());
        if (extName == null)
            throw new IllegalStateException("Fail to get extension(org.apache.dubbo.rpc.Protocol) name from url("
                    + url.toString() + ") use keys([protocol])");
        org.apache.dubbo.rpc.Protocol extension = (org.apache.dubbo.rpc.Protocol) ExtensionLoader
                .getExtensionLoader(org.apache.dubbo.rpc.Protocol.class).getExtension(extName);
        return extension.export(arg0);
    }
}

[carryxyh]

Get it. I agree with u. The code readability here needs to be improved. Maybe it will be better soon. 😃

[zonghaishang]

Understand the default SPI extension point name is “” better understanding，I feel that the current implementation is working well. Some opinions are not in favor of being modified to a required value. At least we should not modify it at present.