diff --git a/CHANGELOG.md b/CHANGELOG.md
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--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,9 @@ eSockd 3.0
 
 MochiWeb 4.0
 
+Log
+
+Async Socket
 ......
 
 
diff --git a/doc/design/ClientSession.md b/doc/design/ClientSession.md
new file mode 100644
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--- /dev/null
+++ b/doc/design/ClientSession.md
@@ -0,0 +1,55 @@
+## Transient Client/Session Sequence1
+
+```
+Client1->SM:  {start_session, {true, ClientId, self()}}
+SM-->Session: {destory, ClientId}
+Session-->Session: {shutdown, destroy}
+Session-->Client2: exit({shutdown, destroy})
+Client2-->CM: {'DOWN', MRef, process, Pid, Reason}
+SM-->Client1: {ok, SessPid}
+Client1-->CM: {register, Client1}
+```
+
+![Transient Client/Session Sequence1](TransientSessionSeq1.png)
+
+## Transient Client/Session Sequence2
+
+
+```
+Client1->SM:  {start_session, {true, ClientId, self()}}
+SM-->Session: {destory, ClientId}
+Session-->Session: {shutdown, destroy}
+SM-->Client1: {ok, SessPid}
+Client1-->CM: {register, Client1}
+Session-->Client2: exit({shutdown, destroy})
+Client2-->CM: {'DOWN', MRef, process, Pid, Reason}
+```
+
+![Transient Client/Session Sequence2](TransientSessionSeq2.png)
+
+## Persistent Client/Session Sequence1
+
+```
+Client1->SM: {start_session, {true, ClientId, self()}}
+SM-->Session: {resume, ClientId, ClientPid}
+Session-->Client2: {shutdown, conflict, {ClientId, Pid}}
+Client2-->CM: {unregister, ClientId, self()}
+SM-->Client1: {ok, SessPid}
+Client1-->CM: {register, Client1}
+```
+
+![Persistent Client/Session Sequence1](PersistentSessionSeq1.png)
+
+
+## Persistent Client/Session Sequence2
+
+```
+Client1->SM: {start_session, {true, ClientId, self()}}
+SM-->Session: {resume, ClientId, ClientPid}
+SM-->Client1: {ok, SessPid}
+Client1-->CM: {register, Client1}
+Session-->Client2: {shutdown, conflict, {ClientId, Pid}}
+Client2-->CM: {unregister, ClientId, self()}
+```
+
+![Persistent Client/Session Sequence2](PersistentSessionSeq2.png)
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