diff --git a/Client-server-discovery-lifecycle.md b/Client-server-discovery-lifecycle.md
index 508a867..aacef45 100644
--- a/Client-server-discovery-lifecycle.md
+++ b/Client-server-discovery-lifecycle.md
@@ -1 +1,12 @@
-For older discussion see [XArchived: Client server discovery lifecycle](./XArchived:-Client-server-discovery-lifecycle)
\ No newline at end of file
+For older discussion see [XArchived: Client server discovery lifecycle](./XArchived:-Client-server-discovery-lifecycle)
+
+### active.json
+
+This file will be placed under `$cwd/project/target/`.
+
+```
+{
+   "portfile": "file:///Users/xxx/.sbt/server/$hash_of_cwd/portfile.json",
+   "url": "tcp://127.0.0.0:xxxx"
+}
+```