diff --git a/hsp/constants.go b/hsp/constants.go
index 4f0ae3d..bba176f 100644
--- a/hsp/constants.go
+++ b/hsp/constants.go
@@ -13,6 +13,8 @@ const (
 	H_STATUS      = "status"
 	H_DATA_FORMAT = "data-format"
 	H_ROUTE       = "route"
+	H_XSTREAM     = "x-stream"
+	H_XSTREAM_KEY = "x-stream-key"
 )
 
 const (
@@ -46,6 +48,11 @@ type DataFormat struct {
 	Encoding string
 }
 
+type StreamInfo struct {
+	TotalBytes uint64
+	BufferSize uint16
+}
+
 func TextDataFormat() *DataFormat {
 	return &DataFormat{Format: DF_TEXT, Encoding: E_UTF8}
 }