diff --git a/src/sleepy/dog.clj b/src/sleepy/dog.clj
index 9f62d18..1cf18e9 100644
--- a/src/sleepy/dog.clj
+++ b/src/sleepy/dog.clj
@@ -8,16 +8,23 @@
 (set! *warn-on-reflection* true)
 (set! *unchecked-math* :warn-on-boxed)
 
+;; just aliases
+
 (defn active-span!
   []
-  (let [tracer (GlobalTracer/get)]
-    (when *continuation* (.activate *continuation*))
-    (.activeSpan tracer)))
+  (datadog/active-span!))
 
 (defn set-resource!
-  [^String reg-name]
-  (let [span (active-span!)]
-    (datadog/tag-span! span DDTags/RESOURCE_NAME reg-name)))
+  [reg-name]
+  (datadog/set-resource! reg-name))
+
+(defn report-error!
+  [span ex]
+  (datadog/report-error! span ex))
+
+(defn root-of
+  [span]
+  (datadog/root-of span))
 
 (defn http-headers
   []
diff --git a/src/sleepy/internal.clj b/src/sleepy/internal.clj
index f7276c2..f59b15b 100644
--- a/src/sleepy/internal.clj
+++ b/src/sleepy/internal.clj
@@ -47,9 +47,16 @@
   (add-tag!
    [_ _ _]))
 
+(defn active-span!
+  []
+  (let [tracer (GlobalTracer/get)]
+    (when *continuation* (.activate *continuation*))
+    (.activeSpan tracer)))
+
 ;; agentが無効だとNoopSpanになるので何もしない実装も準備
 (defprotocol Span
   (tag-span! [span k v])
+  (root-of [span])
   (report-error! [span ex]))
 
 (extend-protocol Span
@@ -57,6 +64,9 @@
   (tag-span!
    [span k v]
    (add-tag! v span k))
+  (root-of
+   [span]
+   (.getLocalRootSpan span))
   (report-error!
    [span ex]
    (.setError span true)
@@ -66,6 +76,8 @@
   NoopSpan
   (tag-span!
    [_ _ _])
+  (root-of
+   [_])
   (report-error!
    [_ _]))