Is path really a must have part for URL?

[chickenlj]

dubbo://30.5.120.36:20890/org.apache.dubbo.samples.basic.api.DemoService?anyhost=true&application=demo-provider&bind.ip=30.5.120.36&bind.port=20890&dubbo=2.0.2&generic=false&interface=org.apache.dubbo.samples.basic.api.DemoService&methods=sayHello&pid=68763&release=2.7.0-SNAPSHOT&side=provider&timestamp=1548142826615

Here, in this example, the path value is /org.apache.dubbo.samples.basic.api.DemoService, it's generaged by default and is the same as interface=org.apache.dubbo.samples.basic.api.DemoService.
I tried to figure out the role path plays in the framework, it seems to have some some meaning for Rest or Http protocols, but is never used for Dubbo protocol.

• Dubbo Protocol

Not used at all except to distinguish two different items in Registry.
Take Zookeeper as an example, the following two items can exist at the same time under the same parent node /dubbo/org.apache.dubbo.samples.basic.api.DemoService/providers only because they have different path.

dubbo://30.5.120.36:20890/org.apache.dubbo.samples.basic.api.DemoService

dubbo://30.5.120.36:20890/org.apache.dubbo.samples.basic.api.DemoService2

• Rest Protocol (maybe works the same way for all http based protocol)

Used to distinguish different rest paths

@Path("users")
@Consumes({MediaType.APPLICATION_JSON, MediaType.TEXT_XML})
@Produces({ContentType.APPLICATION_JSON_UTF_8, ContentType.TEXT_XML_UTF_8})
@Api(value = "UserService")
public interface UserService {

    @GET
    @Path("{id : \\d+}")
    @ApiOperation(value = "getUser")
    User getUser(@ApiParam(value = "id") @PathParam("id")Long id);

    Long registerUser(User user);
}

dubbo://30.5.120.36:20890/{your-path}/users/{id}

[chickenlj]

At least, if it's not mandatory, is it possible for us to stop giving it a default value and just leave it empty?

Or maybe I still don't get it's real design purpose.

[chickenlj]

https://github.com/apache/incubator-dubbo/blob/e07038b00e057bb3cd6989252534b581039916f9/dubbo-rpc/dubbo-rpc-dubbo/src/main/java/org/apache/dubbo/rpc/protocol/dubbo/DubboProtocol.java#L227

Uses path to locate exporter instead of using interface name.

[chickenlj]

#3017

[chickenlj]

#3328