Tp 55555/integrate document service client (#5)

* TP-55555 | document client and kafka integration

* TP-55555 | introduce service concept refactor code

pkg/encoder/encoder.go

@@ -0,0 +1,28 @@
+package encoder
+
+import (
+	"encoding/json"
+	"fmt"
+	"google.golang.org/protobuf/proto"
+)
+
+type Encoder interface {
+	Encode(v interface{}) ([]byte, error)
+}
+
+type JsonEncoder struct{}
+type ProtoEncoder struct{}
+
+var JsonEncoderInstance = &JsonEncoder{}
+var ProtoEncoderInstance = &ProtoEncoder{}
+
+func (j *JsonEncoder) Encode(v interface{}) ([]byte, error) {
+	return json.Marshal(v)
+}
+
+func (p *ProtoEncoder) Encode(v interface{}) ([]byte, error) {
+	if message, ok := v.(proto.Message); ok {
+		return proto.Marshal(message)
+	}
+	return nil, fmt.Errorf("not a proto message")
+}