英文:
JSONRPC server returns empty result
问题
我编写了一个简单的JSONRPC服务器来测试Go的功能，但是我卡住了，总是得到一个空的结果，没有错误和正确的id。我有以下的Go代码：
package main
import (
"log"
"net"
"net/rpc"
"net/rpc/jsonrpc"
)
type Experiment int
func (e *Experiment) Test(i *string, reply *string) error {
s := "Hello, " + *i
reply = &s
log.Println(s, reply)
return nil
}
func main() {
exp := new(Experiment)
server := rpc.NewServer()
server.Register(exp)
l, err := net.Listen("tcp", ":1234")
if err != nil {
log.Fatal("listen error:", err)
}
for {
conn, err := l.Accept()
if err != nil {
log.Fatal(err)
}
server.ServeCodec(jsonrpc.NewServerCodec(conn))
}
}
无论我尝试什么，我总是得到以下的响应：
{"id":1,"result":"","error":null}
日志显示服务器的一切都按照预期工作。
2013/07/17 15:17:13 Hello, Paulo 0xc200090ac0
对于发生了什么事情有什么想法吗？我正在使用最新稳定版本的Go，v1.1.1
谢谢
英文:
I've coded a simple JSONRPC server to test Go's capabilities, but I'm stuck, always getting an empty result, without error and correct id. I've got the following Go code:
package main
import (
"log"
"net"
"net/rpc"
"net/rpc/jsonrpc"
)
type Experiment int
func (e *Experiment) Test(i *string, reply *string) error {
s := "Hello, " + *i
reply = &s
log.Println(s, reply)
return nil
}
func main() {
exp := new(Experiment)
server := rpc.NewServer()
server.Register(exp)
l, err := net.Listen("tcp", ":1234")
if err != nil {
log.Fatal("listen error:", err)
}
for {
conn, err := l.Accept()
if err != nil {
log.Fatal(err)
}
server.ServeCodec(jsonrpc.NewServerCodec(conn))
}
}
No matter what I tried, I've always got the following response:
{"id":1,"result":"","error":null}
Logging shows everything is working as it should in the server.
2013/07/17 15:17:13 Hello, Paulo 0xc200090ac0
Any ideas on what's going on? I'm using the latest stable version of Go, v1.1.1
Thanks
答案1
得分: 4
你的回复是指向字符串的指针类型。这是可以的，甚至是必需的，因为第二个参数用于返回答案。但是你接着做了以下操作：
s := "Hello, " + *i
reply = &s
这相当于：
- 构造一个新的字符串并赋予一个新的值。
- 让reply指向这个新的字符串。
这样做不会对返回的字符串产生任何影响。
尝试一下：
*reply = s
英文:
Your reply is of type pointer to string. That is okay and even required as the second argument is used to return the answer. But then you do:
s := "Hello, " + *i
reply = &s
Which translates to:
- Construct a new string with a new value.
- Let reply point to this new string
This lets the string which is returned completely unaffected.
Try
*reply = s
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