jrpc

jrpc - rpc with json

jrpc library provides client and server for RPC-like communication over HTTP with json encoded messages. The protocol is a somewhat simplified version of json-rpc with a single POST call sending Request json (method name and the list of parameters) moreover, receiving json Response with result data and an error string.

Usage

Plugin (server)

// Plugin wraps jrpc.Server and adds synced map to store data
type Plugin struct {
	*jrpc.Server
}

// create plugin (jrpc server) with NewServer where required param is a base url for rpc calls
plugin := NewServer("/command")

// then add you function to map 
plugin.Add("mycommand", func(id uint64, params json.RawMessage) Response {
    return jrpc.EncodeResponse(id, "hello, it works", nil)
})

// and run server with port number value
plugin.Run(9090)

The constructor NewServer accept two parameters:

• API - a base url for rpc calls
• Options - optional parameters such is timeouts, logger, limits, middlewares and etc.
  • Auth - set credentials basic auth to server, accepts username and password
  • WithTimeout - sets global timeouts for server requests, such as read, write and idle. Call accept Timeouts struct.
  • WithLimits - define limit for server call, accepts limit value in float64 type
  • WithThrottler - sets throttler middleware with specify limit value
  • WithtSignature - sets server signature, accept appName, author and version. Disable by default.
  • WithLogger - define custom logger (e.g. lgr)
  • WithMiddlewares - sets custom middlewares list to server, accepts list of handler with idiomatic type func(http.Handler) http.Handler

Example with options:

plugin := NewServer("/command",
	    Auth("user", "password"),
		WithTimeout(Timeouts{ReadHeaderTimeout: 5 * time.Second, WriteTimeout: 5 * time.Second, IdleTimeout: 10 * time.Second}),
		WithThrottler(120),
		WithLimits(100),
        WithtSignature("the best plugin ever", "author", "1.0.0"),
		WithMiddlewares(middleware.Heartbeat('/ping'), middleware.Profiler, middleware.StripSlashes),
)

Application (client)

// Client makes jrpc.Client and invoke remote call
rpcClient := jrpc.Client{
    API:        "http://127.0.0.1:8080/command",
    Client:     http.Client{},
    AuthUser:   "user",
    AuthPasswd: "password",
}

resp, err := rpcClient.Call("mycommand")
var message string
if err = json.Unmarshal(*resp.Result, &message); err != nil {
    panic(err)
}

for functional examples for both plugin and application see _example

Technical details

• jrpc.Server runs on user-defined port as a regular http server
• Server accepts a single POST request on user-defined url with Request sent as json payload

 ```go
 type Request struct {
 	Method string      `json:"method"`
 	Params interface{} `json:"params,omitempty"`
 	ID     uint64      `json:"id"`
 }
 ```
 example: 
 
 ```json
   {
    "method":"test",
    "params":[123,"abc"],
    "id":1
    }
 ```

• Params can be a struct, primitive type or slice of values, even with different types.
• Server defines ServerFn handler function to react on a POST request. The handler provided by the user.
• Communication between the server and the caller can be protected with basic auth.
• Client provides a single method Call and return Response

 // Response encloses result and error received from remote server
 type Response struct {
 	Result *json.RawMessage `json:"result,omitempty"`
 	Error  string           `json:"error,omitempty"`
 	ID     uint64           `json:"id"`
 }

• User should encode and decode json payloads on the application level, see provided examples
• jrpc.Server doesn't support https internally (yet). If used on exposed or non-private networks, should be proxied with something providing https termination (nginx and others).

Status

The code was extracted from remark42 and still under development. Until v1.x released the API & protocol may change.