2 files changed, 40 insertions, 6 deletions

diff --git a/cpp/src/qpid/framing/SessionState.cpp b/cpp/src/qpid/framing/SessionState.cpp
index 7e905bdf63..8056f4a523 100644
--- a/cpp/src/qpid/framing/SessionState.cpp
+++ b/cpp/src/qpid/framing/SessionState.cpp
@@ -33,6 +33,7 @@ namespace qpid {
 namespace framing {
 
 SessionState::SessionState(uint32_t ack,  const Uuid& uuid) :
+    state(ATTACHED),
     id(uuid),
     lastReceived(-1),
     lastSent(-1),
@@ -44,6 +45,7 @@ SessionState::SessionState(uint32_t ack,  const Uuid& uuid) :
 {}
 
 SessionState::SessionState(const Uuid& uuid) :
+    state(ATTACHED),
     id(uuid),
     lastReceived(-1),
     lastSent(-1),
@@ -63,6 +65,10 @@ bool isSessionCommand(const AMQFrame& f) {
 boost::optional<SequenceNumber> SessionState::received(const AMQFrame& f) {
     if (isSessionCommand(f))
         return boost::none;
+    if (state==RESUMING)
+        throw CommandInvalidException(
+            QPID_MSG("Invalid frame: Resuming session, expected session-ack"));
+    assert(state = ATTACHED);
     ++lastReceived;
     QPID_LOG(trace, "Recv # "<< lastReceived << " " << id);
     if (ackInterval && lastReceived == sendAckAt)
@@ -79,6 +85,7 @@ bool SessionState::sent(const AMQFrame& f) {
     ++lastSent;
     QPID_LOG(trace, "Sent # "<< lastSent << " " << id);
     return ackInterval &&
+        (state!=RESUMING) &&
         (lastSent == solicitAckAt) &&
         sendingSolicit();
 }
@@ -90,6 +97,8 @@ SessionState::Replay SessionState::replay() {
 }
 
 void SessionState::receivedAck(SequenceNumber acked) {
+    if (state==RESUMING) state=ATTACHED;
+    assert(state==ATTACHED);
      if (lastSent < acked)
         throw InvalidArgumentException("Invalid sequence number in ack");
     size_t keep = lastSent - acked;
@@ -104,10 +113,22 @@ SequenceNumber SessionState::sendingAck() {
 }
 
 bool SessionState::sendingSolicit() {
+    assert(state == ATTACHED);
     if (ackSolicited)
         return false;
     solicitAckAt = lastSent + ackInterval;
     return ackInterval != 0;
 }
 
+SequenceNumber SessionState::resuming() {
+    if (!resumable)
+        throw InternalErrorException("Session is not resumable");
+    state = RESUMING;
+    return sendingAck();
+}
+
+void SessionState::suspend() {
+    state = SUSPENDED;
+}
+
 }} // namespace qpid::framing
diff --git a/cpp/src/qpid/framing/SessionState.h b/cpp/src/qpid/framing/SessionState.h
index 5034de4e94..361c960db1 100644
--- a/cpp/src/qpid/framing/SessionState.h
+++ b/cpp/src/qpid/framing/SessionState.h
@@ -35,10 +35,7 @@ namespace framing {
 
 /**
  * Session state common to client and broker.
- * 
- * Stores data needed to resume a session: replay frames, implements
- * session ack/resume protcools. Stores handler chains for the session,
- * handlers may themselves store state.
+ * Stores replay frames, implements session ack/resume protcools.
  *
  * A SessionState is always associated with an _open_ session (attached or
  * suspended) it is destroyed when the session is closed.
@@ -49,6 +46,13 @@ class SessionState
   public:
     typedef std::vector<AMQFrame> Replay;
 
+    /** States of a session. */
+    enum State {
+        SUSPENDED, ///< Suspended, detached from any channel.
+        RESUMING, ///< Resuming: waiting for initial ack from peer.
+        ATTACHED ///< Attached to channel and operating normally.
+    };
+
     /**
      *Create a newly opened active session.
      *@param ackInterval send/solicit an ack whenever N unacked frames
@@ -56,8 +60,7 @@ class SessionState
      * 
      * N=0 disables voluntary send/solict ack.
      */
-    SessionState(uint32_t ackInterval,
-                 const framing::Uuid& id=framing::Uuid(true));
+    SessionState(uint32_t ackInterval, const framing::Uuid& id=framing::Uuid(true));
 
     /**
      * Create a non-resumable session. Does not store session frames,
@@ -66,6 +69,7 @@ class SessionState
     SessionState(const framing::Uuid& id=framing::Uuid(true));
 
     const framing::Uuid& getId() const { return id; }
+    State getState() const { return state; }
     
     /** Received incoming L3 frame.
      * @return SequenceNumber if an ack should be sent, empty otherwise.
@@ -88,6 +92,13 @@ class SessionState
      */
     Replay replay();
 
+    /** Suspend the session. */
+    void suspend();
+
+    /** Start resume protocol for the session.
+     *@returns sequence number to ack immediately.  */
+    SequenceNumber resuming();
+
     /** About to send an unscheduled ack, e.g. to respond to a solicit-ack.
      * 
      * Note: when received() returns a sequence number this function
@@ -104,7 +115,9 @@ class SessionState
 
     bool sendingSolicit();
 
+    State state;
     framing::Uuid id;
+
     Unacked unackedOut;
     SequenceNumber lastReceived;
     SequenceNumber lastSent;