diff --git a/proxy/exchange.go b/proxy/exchange.go
new file mode 100644
index 0000000..35c6460
--- /dev/null
+++ b/proxy/exchange.go
@@ -0,0 +1,7 @@
+package proxy
+
+type Exchange interface {
+	Complete() bool
+	Initial() (out []byte, err error)
+	Handle(in []byte) (out []byte, data []byte, err error)
+}