add error code definition

edge/pkg/appsd/model/err.go

@@ -0,0 +1,31 @@
+package model
+
+import "fmt"
+
+type Error struct  {
+	Status  int    `json:"-"`
+	Code    string `json:"code"`
+	Message string `json:"msg"`
+}
+
+func (e *Error) Error() string {
+	return fmt.Sprintf("error:status=%v code=%s, message=%s", e.Status, e.Code, e.Message)
+}
+
+func New(status int, code, message string) *Error {
+	return &Error{
+		Status:  status,
+		Code:    code,
+		Message: message,
+	}
+}
+
+var (
+	Success             = New(200, "1000", "Success")
+	ErrInvalidParam     = New(400, "1002", "Invalid parameter")
+	ErrCertEmpty        = New(403, "1112", "Domain has no cert")
+	ErrRequestMethod    = New(405, "1113", "Request method error")
+	ErrInternalServer   = New(500, "1001", "Internal server error")
+	ErrJsonUnmarshal    = New(500, "1107", "Json unmarshal error")
+	ErrFormatResponse   = New(500, "1108", "Format http response error")
+)