diff --git a/compos/common/lib.rs b/compos/common/lib.rs
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+++ b/compos/common/lib.rs
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+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//! Common items used by CompOS server and/or clients
+
+pub mod compos_client;
+
+/// VSock port that the CompOS server listens on for RPC binder connections. This should be out of
+/// future port range (if happens) that microdroid may reserve for system components.
+pub const COMPOS_VSOCK_PORT: u32 = 6432;
+
+/// The root directory where the CompOS APEX is mounted (read only).
+pub const COMPOS_APEX_ROOT: &str = "/apex/com.android.compos";
+
+/// The root of the  data directory available for private use by the CompOS APEX.
+pub const COMPOS_DATA_ROOT: &str = "/data/misc/apexdata/com.android.compos";