# jrpc - rpc with json [](https://github.com/go-pkgz/jrpc/actions/workflows/ci.yml) [](https://goreportcard.com/report/github.com/go-pkgz/jrpc) [](https://coveralls.io/github/go-pkgz/jrpc?branch=master) [](https://godoc.org/github.com/go-pkgz/jrpc)
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)
```go
// 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](https://github.com/go-pkgz/lgr))
* `WithMiddlewares` - sets custom middlewares list to server, accepts list of handler with idiomatic type `func(http.Handler) http.Handler`
Example with options:
```go
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)
```go
// 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](https://github.com/go-pkgz/jrpc/tree/master/_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](https://github.com/go-pkgz/jrpc/blob/master/jrpc.go#L12) sent as json payload
request details and an example:
```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
}
```
response details:
```go
// 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"`
}
```