refactor api server around rpc services

pkg/rpc/envelope.go

@@ -0,0 +1,37 @@
+package rpc
+
+import (
+	"encoding/json"
+	"strings"
+)
+
+type Request struct {
+	Method    string          `json:"method"`
+	Params    json.RawMessage `json:"params,omitempty"`
+	RequestID string          `json:"request_id,omitempty"`
+}
+
+type Response struct {
+	OK        bool        `json:"ok"`
+	Result    interface{} `json:"result,omitempty"`
+	Error     *Error      `json:"error,omitempty"`
+	RequestID string      `json:"request_id,omitempty"`
+}
+
+type Error struct {
+	Code      string      `json:"code"`
+	Message   string      `json:"message"`
+	Details   interface{} `json:"details,omitempty"`
+	Retryable bool        `json:"retryable,omitempty"`
+}
+
+func (r Request) NormalizedMethod() string {
+	return strings.ToLower(strings.TrimSpace(r.Method))
+}
+
+func DecodeParams(raw json.RawMessage, target interface{}) error {
+	if len(raw) == 0 || string(raw) == "null" {
+		return nil
+	}
+	return json.Unmarshal(raw, target)
+}