Example of proxy for using JSON-RPC in Go via HTTP.

jsonrpc-http.go

package main

import (
  "bufio"
	"bytes"
	"fmt"
	"log"
	"net/http"
	"net/rpc/jsonrpc"
)

type proxy struct {
	url        string
	httpClient *http.Client
	cookies    []*http.Cookie

	request *http.Request
}

func (p *proxy) Read(b []byte) (int, error) {
	resp, err := p.httpClient.Do(p.request)
	if err != nil {
		return 0, err
	}

	if p.cookies == nil {
		p.cookies = resp.Cookies()
	}

	r := bufio.NewReader(resp.Body)
	n, err := r.Read(b)
	if err != nil {
		return 0, nil
	}

	resp.Body.Close()

	return n, nil
}

func (p *proxy) Write(b []byte) (int, error) {
	req, err := http.NewRequest("POST", p.url, bytes.NewReader(b))
	if err != nil {
		return 0, err
	}

	n := len(b)

	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Content-Length", fmt.Sprintf("%d", n))

	if p.cookies != nil {
		for _, cookie := range p.cookies {
			req.AddCookie(cookie)
		}
	}

	p.request = req

	return n, nil
}

func (p *proxy) Close() error {
	return nil
}

func newProxy(url string, transport *http.Transport) *proxy {
	if transport == nil {
		transport = &http.Transport{}
	}

	httpClient := &http.Client{Transport: transport}

	return &proxy{
		url:        url,
		httpClient: httpClient,
	}
}

func main() {
	proxy := newProxy("https://bugzilla.mozilla.org/jsonrpc.cgi", nil)

	client := jsonrpc.NewClient(proxy)

	result := map[string]interface{}{}
	err := client.Call("Bugzilla.version", nil, &result)
	if err != nil {
		log.Printf("Error: %s\n", err.Error())
		return
	}

	log.Printf("Version = %v\n", result["version"])
}

There is a problem, proxy#Read called twice, presumably by Decode method of json.Decoder, but I'm not sure.