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

request details and an example:

type Request struct {
   Method string      `json:"method"`
   Params interface{} `json:"params,omitempty"`
   ID     uint64      `json:"id"`
}

example:

  {
   "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 details:

 // 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.