JSON RPC Client Go - json

Question

I have a python server serving response through JSON-RPC. Here is a sample response from the server.
'{"jsonrpc": "2.0", "result": "Peer 1: local 10.10.0.2 remote 10.10.0.1 state CONNECT\\nPeer 2: local 10.10.0.18 remote 10.10.0.17 state ESTABLISHED\\nPeer 3: local 10.10.0.10 remote 10.10.0.9 state ESTABLISHED", "id": "839732f9-cf36-46ff-8b9b-6120250d9ce5"}'
Here is the request I need to send to the server:
'{"method":"echo","jsonrpc":"2.0","params":["test_params"],"id":"839732f9-cf36-46ff-8b9b-6120250d9ce5"}'
Here is my client with go language:
package main
import (
"fmt"
"log"
"net"
"net/rpc/jsonrpc"
)
type Args struct {
jsonrpc, id string
}
func main() {
conn, err := net.Dial("tcp", "11.21.22.221:8080")
if err != nil {
panic(err)
}
defer conn.Close()
args := Args{"2.0", "d87198f0-af92-49f8-9a7d-ab8bed5c4d17"}
var reply string
c := jsonrpc.NewClient(conn)
err = c.Call("echo", args, &reply)
if err != nil {
log.Fatal("error:", err)
}
fmt.Printf("Response: %d", reply)
}
But, when I run this client, it is not sending anything in the params. Instead it is sending empty params like this:
'{"method":"echo","params":[{}],"id":0}\n
Can somebody help me telling what mistake I am making? I am a newbie to go language.
Thanks.

Answer 1

I don't think what you are doing is possible using the client as provided by go because the private clientRequest struct is currently defined as:
type clientRequest struct {
Method string `json:"method"`
Params [1]interface{} `json:"params"`
Id uint64 `json:"id"`
}
What you pass into Call as args is stuck into Params and note how there is no "Version `json:"jsonrpc"`" inside of that struct.
AFAICT (which may be wrong, this is my first time reading through this code) you would need to implement your own ClientCodec. You could probably get away with copying most (all) of the parts out of the stdlib and add the field to the clientRequest above. ;-)