diff --git a/common/JackAudioDriver.cpp b/common/JackAudioDriver.cpp
index 31b8a51b..00b004f7 100644
--- a/common/JackAudioDriver.cpp
+++ b/common/JackAudioDriver.cpp
@@ -141,7 +141,7 @@ int JackAudioDriver::Attach()
     for (i = 0; i < fCaptureChannels; i++) {
         snprintf(alias, sizeof(alias) - 1, "%s:%s:out%d", fAliasName, fCaptureDriverName, i + 1);
         snprintf(name, sizeof(name) - 1, "%s:capture_%d", fClientControl.fName, i + 1);
-        if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, CaptureDriverFlags, fEngineControl->fBufferSize)) == NO_PORT) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, CaptureDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error("driver: cannot register port for %s", name);
             return -1;
         }
@@ -154,7 +154,7 @@ int JackAudioDriver::Attach()
     for (i = 0; i < fPlaybackChannels; i++) {
         snprintf(alias, sizeof(alias) - 1, "%s:%s:in%d", fAliasName, fPlaybackDriverName, i + 1);
         snprintf(name, sizeof(name) - 1, "%s:playback_%d", fClientControl.fName, i + 1);
-        if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, PlaybackDriverFlags, fEngineControl->fBufferSize)) == NO_PORT) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, PlaybackDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error("driver: cannot register port for %s", name);
             return -1;
         }
@@ -167,7 +167,7 @@ int JackAudioDriver::Attach()
         if (fWithMonitorPorts) {
             jack_log("Create monitor port");
             snprintf(name, sizeof(name) - 1, "%s:monitor_%u", fClientControl.fName, i + 1);
-            if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, fEngineControl->fBufferSize)) == NO_PORT) {
+            if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, fEngineControl->fBufferSize, &port_index) < 0) {
                 jack_error("Cannot register monitor port for %s", name);
                 return -1;
             } else {
@@ -186,13 +186,14 @@ int JackAudioDriver::Detach()
     jack_log("JackAudioDriver::Detach");
 
     for (i = 0; i < fCaptureChannels; i++) {
-        fGraphManager->ReleasePort(fClientControl.fRefNum, fCapturePortList[i]);
+        fEngine->PortUnRegister(fClientControl.fRefNum, fCapturePortList[i]);
     }
 
     for (i = 0; i < fPlaybackChannels; i++) {
-        fGraphManager->ReleasePort(fClientControl.fRefNum, fPlaybackPortList[i]);
-        if (fWithMonitorPorts)
-            fGraphManager->ReleasePort(fClientControl.fRefNum, fMonitorPortList[i]);
+        fEngine->PortUnRegister(fClientControl.fRefNum, fPlaybackPortList[i]);
+        if (fWithMonitorPorts) {
+            fEngine->PortUnRegister(fClientControl.fRefNum, fMonitorPortList[i]);
+        }
     }
 
     return 0;
diff --git a/common/JackEngine.cpp b/common/JackEngine.cpp
index 2c7db9e3..998cb651 100644
--- a/common/JackEngine.cpp
+++ b/common/JackEngine.cpp
@@ -804,7 +804,7 @@ int JackEngine::PortRegister(int refnum, const char* name, const char *type, uns
         return -1;
     }
 
-    *port_index = fGraphManager->AllocatePort(refnum, name, type, (JackPortFlags)flags, fEngineControl->fBufferSize);
+    *port_index = fGraphManager->AllocatePort(refnum, name, type, (JackPortFlags)flags, buffer_size);
     if (*port_index != NO_PORT) {
         if (client->GetClientControl()->fActive)
             NotifyPortRegistation(*port_index, true);
diff --git a/common/JackLockedEngine.h b/common/JackLockedEngine.h
index c311f57d..45b1c6a0 100644
--- a/common/JackLockedEngine.h
+++ b/common/JackLockedEngine.h
@@ -261,6 +261,7 @@ class SERVER_EXPORT JackLockedEngine
             fEngine.NotifyGraphReorder();
             CATCH_EXCEPTION
         }
+
         void NotifyBufferSize(jack_nframes_t buffer_size)
         {
             TRY_CALL
diff --git a/common/JackMidiDriver.cpp b/common/JackMidiDriver.cpp
index 1fbd1e38..86001ae2 100644
--- a/common/JackMidiDriver.cpp
+++ b/common/JackMidiDriver.cpp
@@ -67,7 +67,7 @@ int JackMidiDriver::Attach()
     for (i = 0; i < fCaptureChannels; i++) {
         snprintf(alias, sizeof(alias) - 1, "%s:%s:out%d", fAliasName, fCaptureDriverName, i + 1);
         snprintf(name, sizeof(name) - 1, "%s:capture_%d", fClientControl.fName, i + 1);
-        if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_MIDI_TYPE, CaptureDriverFlags, fEngineControl->fBufferSize)) == NO_PORT) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_MIDI_TYPE, CaptureDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error("driver: cannot register port for %s", name);
             return -1;
         }
@@ -80,7 +80,7 @@ int JackMidiDriver::Attach()
     for (i = 0; i < fPlaybackChannels; i++) {
         snprintf(alias, sizeof(alias) - 1, "%s:%s:in%d", fAliasName, fPlaybackDriverName, i + 1);
         snprintf(name, sizeof(name) - 1, "%s:playback_%d", fClientControl.fName, i + 1);
-        if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_MIDI_TYPE, PlaybackDriverFlags, fEngineControl->fBufferSize)) == NO_PORT) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_MIDI_TYPE, PlaybackDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error("driver: cannot register port for %s", name);
             return -1;
         }
@@ -100,11 +100,11 @@ int JackMidiDriver::Detach()
     jack_log("JackMidiDriver::Detach");
 
     for (i = 0; i < fCaptureChannels; i++) {
-        fGraphManager->ReleasePort(fClientControl.fRefNum, fCapturePortList[i]);
+        fEngine->PortUnRegister(fClientControl.fRefNum, fCapturePortList[i]);
     }
 
     for (i = 0; i < fPlaybackChannels; i++) {
-        fGraphManager->ReleasePort(fClientControl.fRefNum, fPlaybackPortList[i]);
+        fEngine->PortUnRegister(fClientControl.fRefNum, fPlaybackPortList[i]);
     }
 
     return 0;
diff --git a/common/JackNetDriver.cpp b/common/JackNetDriver.cpp
index 6726c0a7..b68cc107 100644
--- a/common/JackNetDriver.cpp
+++ b/common/JackNetDriver.cpp
@@ -19,10 +19,10 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
 #include "JackNetDriver.h"
 #include "JackEngineControl.h"
+#include "JackLockedEngine.h"
 #include "JackGraphManager.h"
 #include "JackWaitThreadedDriver.h"
 
-
 using namespace std;
 
 namespace Jack
@@ -268,7 +268,7 @@ namespace Jack
         jack_log("JackNetDriver::AllocPorts fBufferSize = %ld fSampleRate = %ld", fEngineControl->fBufferSize, fEngineControl->fSampleRate);
 
         JackPort* port;
-        jack_port_id_t port_id;
+        jack_port_id_t port_index;
         char name[JACK_CLIENT_NAME_SIZE + JACK_PORT_NAME_SIZE];
         char alias[JACK_CLIENT_NAME_SIZE + JACK_PORT_NAME_SIZE];
         unsigned long port_flags;
@@ -282,32 +282,32 @@ namespace Jack
         {
             snprintf(alias, sizeof(alias) - 1, "%s:%s:out%d", fAliasName, fCaptureDriverName, audio_port_index + 1);
             snprintf(name, sizeof(name) - 1, "%s:capture_%d", fClientControl.fName, audio_port_index + 1);
-            if ((port_id = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE,
-                             static_cast<JackPortFlags>(port_flags), fEngineControl->fBufferSize)) == NO_PORT)
+            if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE,
+                             static_cast<JackPortFlags>(port_flags), fEngineControl->fBufferSize, &port_index) < 0)
             {
                 jack_error("driver: cannot register port for %s", name);
                 return -1;
             }
-            port = fGraphManager->GetPort(port_id);
+            port = fGraphManager->GetPort(port_index);
             port->SetAlias(alias);
             //port latency
             range.min = range.max = fEngineControl->fBufferSize;
             port->SetLatencyRange(JackCaptureLatency, &range);
-            fCapturePortList[audio_port_index] = port_id;
-            jack_log("JackNetDriver::AllocPorts() fCapturePortList[%d] audio_port_index = %ld fPortLatency = %ld", audio_port_index, port_id, port->GetLatency());
+            fCapturePortList[audio_port_index] = port_index;
+            jack_log("JackNetDriver::AllocPorts() fCapturePortList[%d] audio_port_index = %ld fPortLatency = %ld", audio_port_index, port_index, port->GetLatency());
         }
         port_flags = JackPortIsInput | JackPortIsPhysical | JackPortIsTerminal;
         for (audio_port_index = 0; audio_port_index < fPlaybackChannels; audio_port_index++)
         {
             snprintf(alias, sizeof(alias) - 1, "%s:%s:in%d", fAliasName, fPlaybackDriverName, audio_port_index + 1);
             snprintf(name, sizeof(name) - 1, "%s:playback_%d",fClientControl.fName, audio_port_index + 1);
-            if ((port_id = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE,
-                             static_cast<JackPortFlags>(port_flags), fEngineControl->fBufferSize)) == NO_PORT)
+            if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE,
+                             static_cast<JackPortFlags>(port_flags), fEngineControl->fBufferSize, &port_index) < 0)
             {
                 jack_error("driver: cannot register port for %s", name);
                 return -1;
             }
-            port = fGraphManager->GetPort(port_id);
+            port = fGraphManager->GetPort(port_index);
             port->SetAlias(alias);
             //port latency
             switch (fParams.fNetworkMode)
@@ -323,8 +323,8 @@ namespace Jack
                     break;
             }
             port->SetLatencyRange(JackPlaybackLatency, &range);
-            fPlaybackPortList[audio_port_index] = port_id;
-            jack_log("JackNetDriver::AllocPorts() fPlaybackPortList[%d] audio_port_index = %ld fPortLatency = %ld", audio_port_index, port_id, port->GetLatency());
+            fPlaybackPortList[audio_port_index] = port_index;
+            jack_log("JackNetDriver::AllocPorts() fPlaybackPortList[%d] audio_port_index = %ld fPortLatency = %ld", audio_port_index, port_index, port->GetLatency());
         }
         //midi
         port_flags = JackPortIsOutput | JackPortIsPhysical | JackPortIsTerminal;
@@ -332,18 +332,18 @@ namespace Jack
         {
             snprintf(alias, sizeof(alias) - 1, "%s:%s:out%d", fAliasName, fCaptureDriverName, midi_port_index + 1);
             snprintf(name, sizeof (name) - 1, "%s:midi_capture_%d", fClientControl.fName, midi_port_index + 1);
-            if ((port_id = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_MIDI_TYPE,
-                             static_cast<JackPortFlags>(port_flags), fEngineControl->fBufferSize)) == NO_PORT)
+            if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_MIDI_TYPE,
+                             static_cast<JackPortFlags>(port_flags), fEngineControl->fBufferSize, &port_index) < 0)
             {
                 jack_error("driver: cannot register port for %s", name);
                 return -1;
             }
-            port = fGraphManager->GetPort(port_id);
+            port = fGraphManager->GetPort(port_index);
             //port latency
             range.min = range.max = fEngineControl->fBufferSize;
             port->SetLatencyRange(JackCaptureLatency, &range);
-            fMidiCapturePortList[midi_port_index] = port_id;
-            jack_log("JackNetDriver::AllocPorts() fMidiCapturePortList[%d] midi_port_index = %ld fPortLatency = %ld", midi_port_index, port_id, port->GetLatency());
+            fMidiCapturePortList[midi_port_index] = port_index;
+            jack_log("JackNetDriver::AllocPorts() fMidiCapturePortList[%d] midi_port_index = %ld fPortLatency = %ld", midi_port_index, port_index, port->GetLatency());
         }
 
         port_flags = JackPortIsInput | JackPortIsPhysical | JackPortIsTerminal;
@@ -351,13 +351,13 @@ namespace Jack
         {
             snprintf(alias, sizeof(alias) - 1, "%s:%s:in%d", fAliasName, fPlaybackDriverName, midi_port_index + 1);
             snprintf(name, sizeof(name) - 1, "%s:midi_playback_%d", fClientControl.fName, midi_port_index + 1);
-            if ((port_id = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_MIDI_TYPE,
-                             static_cast<JackPortFlags>(port_flags), fEngineControl->fBufferSize)) == NO_PORT)
+            if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_MIDI_TYPE,
+                             static_cast<JackPortFlags>(port_flags), fEngineControl->fBufferSize, &port_index) < 0)
             {
                 jack_error("driver: cannot register port for %s", name);
                 return -1;
             }
-            port = fGraphManager->GetPort(port_id);
+            port = fGraphManager->GetPort(port_index);
             //port latency
             switch (fParams.fNetworkMode)
             {
@@ -372,8 +372,8 @@ namespace Jack
                     break;
             }
             port->SetLatencyRange(JackPlaybackLatency, &range);
-            fMidiPlaybackPortList[midi_port_index] = port_id;
-            jack_log("JackNetDriver::AllocPorts() fMidiPlaybackPortList[%d] midi_port_index = %ld fPortLatency = %ld", midi_port_index, port_id, port->GetLatency());
+            fMidiPlaybackPortList[midi_port_index] = port_index;
+            jack_log("JackNetDriver::AllocPorts() fMidiPlaybackPortList[%d] midi_port_index = %ld fPortLatency = %ld", midi_port_index, port_index, port->GetLatency());
         }
 
         return 0;
@@ -385,14 +385,14 @@ namespace Jack
 
         for (int audio_port_index = 0; audio_port_index < fCaptureChannels; audio_port_index++) {
             if (fCapturePortList[audio_port_index] > 0) {
-                fGraphManager->ReleasePort(fClientControl.fRefNum, fCapturePortList[audio_port_index]);
+                fEngine->PortUnRegister(fClientControl.fRefNum, fCapturePortList[audio_port_index]);
                 fCapturePortList[audio_port_index] = 0;
             }
         }
 
         for (int audio_port_index = 0; audio_port_index < fPlaybackChannels; audio_port_index++) {
             if (fPlaybackPortList[audio_port_index] > 0) {
-                fGraphManager->ReleasePort(fClientControl.fRefNum, fPlaybackPortList[audio_port_index]);
+                fEngine->PortUnRegister(fClientControl.fRefNum, fPlaybackPortList[audio_port_index]);
                 fPlaybackPortList[audio_port_index] = 0;
             }
         }
@@ -406,7 +406,7 @@ namespace Jack
 
         for (int midi_port_index = 0; midi_port_index < fParams.fReturnMidiChannels; midi_port_index++) {
             if (fMidiPlaybackPortList && fMidiPlaybackPortList[midi_port_index] > 0) {
-                fGraphManager->ReleasePort(fClientControl.fRefNum, fMidiPlaybackPortList[midi_port_index]);
+                fEngine->PortUnRegister(fClientControl.fRefNum, fMidiPlaybackPortList[midi_port_index]);
                 fMidiPlaybackPortList[midi_port_index] = 0;
             }
         }
diff --git a/common/JackNetOneDriver.cpp b/common/JackNetOneDriver.cpp
index 7da0ad8c..d0d5974d 100644
--- a/common/JackNetOneDriver.cpp
+++ b/common/JackNetOneDriver.cpp
@@ -23,6 +23,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
 #include "JackNetOneDriver.h"
 #include "JackEngineControl.h"
+#include "JackLockedEngine.h"
 #include "JackGraphManager.h"
 #include "JackWaitThreadedDriver.h"
 #include "JackTools.h"
@@ -135,7 +136,7 @@ int JackNetOneDriver::Detach()
 
 int JackNetOneDriver::AllocPorts()
 {
-    jack_port_id_t port_id;
+    jack_port_id_t port_index;
     char buf[64];
     unsigned int chn;
 
@@ -145,16 +146,16 @@ int JackNetOneDriver::AllocPorts()
     for (chn = 0; chn < netj.capture_channels_audio; chn++) {
         snprintf (buf, sizeof(buf) - 1, "system:capture_%u", chn + 1);
 
-        if ( ( port_id = fGraphManager->AllocatePort ( fClientControl.fRefNum, buf, JACK_DEFAULT_AUDIO_TYPE,
-                         CaptureDriverFlags, fEngineControl->fBufferSize ) ) == NO_PORT ) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, buf, JACK_DEFAULT_AUDIO_TYPE,
+            CaptureDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error ( "driver: cannot register port for %s", buf );
             return -1;
         }
-        //port = fGraphManager->GetPort ( port_id );
+        //port = fGraphManager->GetPort ( port_index );
 
-        netj.capture_ports = jack_slist_append (netj.capture_ports, (void *)(intptr_t)port_id);
+        netj.capture_ports = jack_slist_append (netj.capture_ports, (void *)(intptr_t)port_index);
 
-        if( netj.bitdepth == CELT_MODE ) {
+        if (netj.bitdepth == CELT_MODE) {
 #if HAVE_CELT
 #if HAVE_CELT_API_0_11
             celt_int32 lookahead;
@@ -178,31 +179,32 @@ int JackNetOneDriver::AllocPorts()
 #endif
         }
     }
+
     for (chn = netj.capture_channels_audio; chn < netj.capture_channels; chn++) {
         snprintf (buf, sizeof(buf) - 1, "system:capture_%u", chn + 1);
 
-        if ( ( port_id = fGraphManager->AllocatePort ( fClientControl.fRefNum, buf, JACK_DEFAULT_MIDI_TYPE,
-                         CaptureDriverFlags, fEngineControl->fBufferSize ) ) == NO_PORT ) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, buf, JACK_DEFAULT_MIDI_TYPE,
+            CaptureDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error ( "driver: cannot register port for %s", buf );
             return -1;
         }
-        //port = fGraphManager->GetPort ( port_id );
+        //port = fGraphManager->GetPort ( port_index );
 
         netj.capture_ports =
-            jack_slist_append (netj.capture_ports, (void *)(intptr_t)port_id);
+            jack_slist_append (netj.capture_ports, (void *)(intptr_t)port_index);
     }
 
     for (chn = 0; chn < netj.playback_channels_audio; chn++) {
         snprintf (buf, sizeof(buf) - 1, "system:playback_%u", chn + 1);
 
-        if ( ( port_id = fGraphManager->AllocatePort ( fClientControl.fRefNum, buf, JACK_DEFAULT_AUDIO_TYPE,
-                         PlaybackDriverFlags, fEngineControl->fBufferSize ) ) == NO_PORT ) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, buf, JACK_DEFAULT_AUDIO_TYPE,
+            PlaybackDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error ( "driver: cannot register port for %s", buf );
             return -1;
         }
-        //port = fGraphManager->GetPort ( port_id );
+        //port = fGraphManager->GetPort ( port_index );
 
-        netj.playback_ports = jack_slist_append (netj.playback_ports, (void *)(intptr_t)port_id);
+        netj.playback_ports = jack_slist_append (netj.playback_ports, (void *)(intptr_t)port_index);
         if( netj.bitdepth == CELT_MODE ) {
 #if HAVE_CELT
 #if HAVE_CELT_API_0_11
@@ -225,15 +227,15 @@ int JackNetOneDriver::AllocPorts()
     for (chn = netj.playback_channels_audio; chn < netj.playback_channels; chn++) {
         snprintf (buf, sizeof(buf) - 1, "system:playback_%u", chn + 1);
 
-        if ( ( port_id = fGraphManager->AllocatePort ( fClientControl.fRefNum, buf, JACK_DEFAULT_MIDI_TYPE,
-                         PlaybackDriverFlags, fEngineControl->fBufferSize ) ) == NO_PORT ) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, buf, JACK_DEFAULT_MIDI_TYPE,
+            PlaybackDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error ( "driver: cannot register port for %s", buf );
             return -1;
         }
-        //port = fGraphManager->GetPort ( port_id );
+        //port = fGraphManager->GetPort ( port_index );
 
         netj.playback_ports =
-            jack_slist_append (netj.playback_ports, (void *)(intptr_t)port_id);
+            jack_slist_append (netj.playback_ports, (void *)(intptr_t)port_index);
     }
     return 0;
 }
@@ -435,20 +437,20 @@ JackNetOneDriver::FreePorts ()
 
     while( node != NULL ) {
         JSList *this_node = node;
-        jack_port_id_t port_id = (jack_port_id_t)(intptr_t) node->data;
+        jack_port_id_t port_index = (jack_port_id_t)(intptr_t) node->data;
         node = jack_slist_remove_link( node, this_node );
         jack_slist_free_1( this_node );
-        fGraphManager->ReleasePort( fClientControl.fRefNum, port_id );
+        fEngine->PortUnRegister(fClientControl.fRefNum, port_index);
     }
     netj.capture_ports = NULL;
 
     node = netj.playback_ports;
     while( node != NULL ) {
         JSList *this_node = node;
-        jack_port_id_t port_id = (jack_port_id_t)(intptr_t) node->data;
+        jack_port_id_t port_index = (jack_port_id_t)(intptr_t) node->data;
         node = jack_slist_remove_link( node, this_node );
         jack_slist_free_1( this_node );
-        fGraphManager->ReleasePort( fClientControl.fRefNum, port_id );
+        fEngine->PortUnRegister(fClientControl.fRefNum, port_index);
     }
     netj.playback_ports = NULL;
 
@@ -522,11 +524,11 @@ JackNetOneDriver::render_payload_to_jack_ports_float ( void *packet_payload, jac
 #if HAVE_SAMPLERATE
         SRC_DATA src;
 #endif
-        jack_port_id_t port_id = (jack_port_id_t)(intptr_t) node->data;
-        JackPort *port = fGraphManager->GetPort( port_id );
+        jack_port_id_t port_index = (jack_port_id_t)(intptr_t) node->data;
+        JackPort *port = fGraphManager->GetPort( port_index );
 
         jack_default_audio_sample_t* buf =
-            (jack_default_audio_sample_t*)fGraphManager->GetBuffer(port_id, fEngineControl->fBufferSize);
+            (jack_default_audio_sample_t*)fGraphManager->GetBuffer(port_index, fEngineControl->fBufferSize);
 
         const char *porttype = port->GetType();
 
@@ -594,11 +596,11 @@ JackNetOneDriver::render_jack_ports_to_payload_float (JSList *playback_ports, JS
 #endif
         unsigned int i;
         int_float_t val;
-        jack_port_id_t port_id = (jack_port_id_t)(intptr_t) node->data;
-        JackPort *port = fGraphManager->GetPort( port_id );
+        jack_port_id_t port_index = (jack_port_id_t)(intptr_t) node->data;
+        JackPort *port = fGraphManager->GetPort( port_index );
 
         jack_default_audio_sample_t* buf =
-            (jack_default_audio_sample_t*)fGraphManager->GetBuffer(port_id, fEngineControl->fBufferSize);
+            (jack_default_audio_sample_t*)fGraphManager->GetBuffer(port_index, fEngineControl->fBufferSize);
 
         const char *porttype = port->GetType();
 
@@ -661,11 +663,11 @@ JackNetOneDriver::render_payload_to_jack_ports_celt (void *packet_payload, jack_
     unsigned char *packet_bufX = (unsigned char *)packet_payload;
 
     while (node != NULL) {
-        jack_port_id_t port_id = (jack_port_id_t) (intptr_t)node->data;
-        JackPort *port = fGraphManager->GetPort( port_id );
+        jack_port_id_t port_index = (jack_port_id_t) (intptr_t)node->data;
+        JackPort *port = fGraphManager->GetPort( port_index );
 
         jack_default_audio_sample_t* buf =
-            (jack_default_audio_sample_t*)fGraphManager->GetBuffer(port_id, fEngineControl->fBufferSize);
+            (jack_default_audio_sample_t*)fGraphManager->GetBuffer(port_index, fEngineControl->fBufferSize);
 
         const char *portname = port->GetType();
 
@@ -710,11 +712,11 @@ JackNetOneDriver::render_jack_ports_to_payload_celt (JSList *playback_ports, JSL
     unsigned char *packet_bufX = (unsigned char *)packet_payload;
 
     while (node != NULL) {
-        jack_port_id_t port_id = (jack_port_id_t) (intptr_t) node->data;
-        JackPort *port = fGraphManager->GetPort( port_id );
+        jack_port_id_t port_index = (jack_port_id_t) (intptr_t) node->data;
+        JackPort *port = fGraphManager->GetPort( port_index );
 
         jack_default_audio_sample_t* buf =
-            (jack_default_audio_sample_t*)fGraphManager->GetBuffer(port_id, fEngineControl->fBufferSize);
+            (jack_default_audio_sample_t*)fGraphManager->GetBuffer(port_index, fEngineControl->fBufferSize);
 
         const char *portname = port->GetType();
 
diff --git a/linux/alsa/JackAlsaDriver.cpp b/linux/alsa/JackAlsaDriver.cpp
index 87338000..9f5c49e1 100644
--- a/linux/alsa/JackAlsaDriver.cpp
+++ b/linux/alsa/JackAlsaDriver.cpp
@@ -94,7 +94,7 @@ void JackAlsaDriver::UpdateLatencies()
 int JackAlsaDriver::Attach()
 {
     JackPort* port;
-    int port_index;
+    jack_port_id_t port_index;
     unsigned long port_flags = (unsigned long)CaptureDriverFlags;
     char name[JACK_CLIENT_NAME_SIZE + JACK_PORT_NAME_SIZE];
     char alias[JACK_CLIENT_NAME_SIZE + JACK_PORT_NAME_SIZE];
@@ -116,7 +116,7 @@ int JackAlsaDriver::Attach()
     for (int i = 0; i < fCaptureChannels; i++) {
         snprintf(alias, sizeof(alias) - 1, "%s:%s:out%d", fAliasName, fCaptureDriverName, i + 1);
         snprintf(name, sizeof(name) - 1, "%s:capture_%d", fClientControl.fName, i + 1);
-        if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, (JackPortFlags)port_flags, fEngineControl->fBufferSize)) == NO_PORT) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, (JackPortFlags)port_flags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error("driver: cannot register port for %s", name);
             return -1;
         }
@@ -131,7 +131,7 @@ int JackAlsaDriver::Attach()
     for (int i = 0; i < fPlaybackChannels; i++) {
         snprintf(alias, sizeof(alias) - 1, "%s:%s:in%d", fAliasName, fPlaybackDriverName, i + 1);
         snprintf(name, sizeof(name) - 1, "%s:playback_%d", fClientControl.fName, i + 1);
-        if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, (JackPortFlags)port_flags, fEngineControl->fBufferSize)) == NO_PORT) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, (JackPortFlags)port_flags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error("driver: cannot register port for %s", name);
             return -1;
         }
@@ -144,8 +144,8 @@ int JackAlsaDriver::Attach()
         if (fWithMonitorPorts) {
             jack_log("Create monitor port");
             snprintf(name, sizeof(name) - 1, "%s:monitor_%d", fClientControl.fName, i + 1);
-            if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, MonitorDriverFlags, fEngineControl->fBufferSize)) == NO_PORT) {
-                jack_error ("ALSA: cannot register monitor port for %s", name);
+            if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, MonitorDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
+                jack_error("ALSA: cannot register monitor port for %s", name);
             } else {
                 fMonitorPortList[i] = port_index;
             }
diff --git a/linux/alsarawmidi/JackALSARawMidiDriver.cpp b/linux/alsarawmidi/JackALSARawMidiDriver.cpp
index 6eabd866..011c8931 100644
--- a/linux/alsarawmidi/JackALSARawMidiDriver.cpp
+++ b/linux/alsarawmidi/JackALSARawMidiDriver.cpp
@@ -68,9 +68,9 @@ JackALSARawMidiDriver::Attach()
     for (int i = 0; i < fCaptureChannels; i++) {
         JackALSARawMidiInputPort *input_port = input_ports[i];
         name = input_port->GetName();
-        index = fGraphManager->AllocatePort(fClientControl.fRefNum, name,
-                                            JACK_DEFAULT_MIDI_TYPE,
-                                            CaptureDriverFlags, buffer_size);
+        fEngine->PortRegister(fClientControl.fRefNum, name,
+                            JACK_DEFAULT_MIDI_TYPE,
+                            CaptureDriverFlags, buffer_size, &index);
         if (index == NO_PORT) {
             jack_error("JackALSARawMidiDriver::Attach - cannot register input "
                        "port with name '%s'.", name);
@@ -85,7 +85,6 @@ JackALSARawMidiDriver::Attach()
 
         jack_info("JackALSARawMidiDriver::Attach - input port registered "
                   "(name='%s', alias='%s').", name, alias);
-
     }
     if (! fEngineControl->fSyncMode) {
         latency += buffer_size;
@@ -95,9 +94,9 @@ JackALSARawMidiDriver::Attach()
     for (int i = 0; i < fPlaybackChannels; i++) {
         JackALSARawMidiOutputPort *output_port = output_ports[i];
         name = output_port->GetName();
-        index = fGraphManager->AllocatePort(fClientControl.fRefNum, name,
-                                            JACK_DEFAULT_MIDI_TYPE,
-                                            PlaybackDriverFlags, buffer_size);
+        fEngine->PortRegister(fClientControl.fRefNum, name,
+                            JACK_DEFAULT_MIDI_TYPE,
+                            PlaybackDriverFlags, buffer_size, &index);
         if (index == NO_PORT) {
             jack_error("JackALSARawMidiDriver::Attach - cannot register "
                        "output port with name '%s'.", name);
@@ -112,7 +111,6 @@ JackALSARawMidiDriver::Attach()
 
         jack_info("JackALSARawMidiDriver::Attach - output port registered "
                   "(name='%s', alias='%s').", name, alias);
-
     }
     return 0;
 }
@@ -156,7 +154,7 @@ JackALSARawMidiDriver::Execute()
             // called.  This means that the amount of time that passes between
             // 'GetMicroSeconds()' and 'ppoll()' is time that will be lost
             // while waiting for 'poll() to timeout.
-            // 
+            //
             // I tried to replace the timeout with a 'timerfd' with absolute
             // times, but, strangely, it actually slowed things down, and made
             // the code a lot more complicated.
diff --git a/linux/firewire/JackFFADODriver.cpp b/linux/firewire/JackFFADODriver.cpp
index 96e0c37c..db04ed3c 100644
--- a/linux/firewire/JackFFADODriver.cpp
+++ b/linux/firewire/JackFFADODriver.cpp
@@ -43,6 +43,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 #include "JackPort.h"
 #include "JackGraphManager.h"
 #include "JackCompilerDeps.h"
+#include "JackLockedEngine.h"
 
 namespace Jack
 {
@@ -345,7 +346,7 @@ JackFFADODriver::ffado_driver_delete (ffado_driver_t *driver)
 int JackFFADODriver::Attach()
 {
     JackPort* port;
-    int port_index;
+    jack_port_id_t port_index;
     char buf[JACK_PORT_NAME_SIZE];
     char portname[JACK_PORT_NAME_SIZE];
     jack_latency_range_t range;
@@ -419,10 +420,10 @@ int JackFFADODriver::Attach()
         if (driver->capture_channels[chn].stream_type == ffado_stream_type_audio) {
             snprintf(buf, sizeof(buf) - 1, "firewire_pcm:%s_in", portname);
             printMessage ("Registering audio capture port %s", buf);
-            if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, buf,
+            if (fEngine->PortRegister(fClientControl.fRefNum, buf,
                               JACK_DEFAULT_AUDIO_TYPE,
                               CaptureDriverFlags,
-                              fEngineControl->fBufferSize)) == NO_PORT) {
+                              fEngineControl->fBufferSize, &port_index) < 0) {
                 jack_error("driver: cannot register port for %s", buf);
                 return -1;
             }
@@ -442,14 +443,13 @@ int JackFFADODriver::Attach()
             fCapturePortList[chn] = port_index;
             jack_log("JackFFADODriver::Attach fCapturePortList[i] %ld ", port_index);
             fCaptureChannels++;
-
         } else if (driver->capture_channels[chn].stream_type == ffado_stream_type_midi) {
             snprintf(buf, sizeof(buf) - 1, "firewire_pcm:%s_in", portname);
             printMessage ("Registering midi capture port %s", buf);
-            if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, buf,
+            if (fEngine->PortRegister(fClientControl.fRefNum, buf,
                               JACK_DEFAULT_MIDI_TYPE,
                               CaptureDriverFlags,
-                              fEngineControl->fBufferSize)) == NO_PORT) {
+                              fEngineControl->fBufferSize, &port_index) < 0) {
                 jack_error("driver: cannot register port for %s", buf);
                 return -1;
             }
@@ -494,10 +494,10 @@ int JackFFADODriver::Attach()
         if (driver->playback_channels[chn].stream_type == ffado_stream_type_audio) {
             snprintf(buf, sizeof(buf) - 1, "firewire_pcm:%s_out", portname);
             printMessage ("Registering audio playback port %s", buf);
-            if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, buf,
+            if (fEngine->PortRegister(fClientControl.fRefNum, buf,
                               JACK_DEFAULT_AUDIO_TYPE,
                               PlaybackDriverFlags,
-                              fEngineControl->fBufferSize)) == NO_PORT) {
+                              fEngineControl->fBufferSize, &port_index) < 0) {
                 jack_error("driver: cannot register port for %s", buf);
                 return -1;
             }
@@ -523,10 +523,11 @@ int JackFFADODriver::Attach()
         } else if (driver->playback_channels[chn].stream_type == ffado_stream_type_midi) {
             snprintf(buf, sizeof(buf) - 1, "firewire_pcm:%s_out", portname);
             printMessage ("Registering midi playback port %s", buf);
-            if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, buf,
+
+            if (fEngine->PortRegister(fClientControl.fRefNum, buf,
                               JACK_DEFAULT_MIDI_TYPE,
                               PlaybackDriverFlags,
-                              fEngineControl->fBufferSize)) == NO_PORT) {
+                              fEngineControl->fBufferSize, &port_index) < 0) {                
                 jack_error("driver: cannot register port for %s", buf);
                 return -1;
             }
diff --git a/linux/freebob/JackFreebobDriver.cpp b/linux/freebob/JackFreebobDriver.cpp
index 14f34815..b9e6ce38 100644
--- a/linux/freebob/JackFreebobDriver.cpp
+++ b/linux/freebob/JackFreebobDriver.cpp
@@ -39,6 +39,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 #include "JackClientControl.h"
 #include "JackPort.h"
 #include "JackGraphManager.h"
+#include "JackLockedEngine.h"
 
 namespace Jack
 {
@@ -666,7 +667,7 @@ JackFreebobDriver::freebob_driver_midi_finish (freebob_driver_midi_handle_t *m)
 int JackFreebobDriver::Attach()
 {
     JackPort* port;
-    int port_index;
+    jack_port_id_t port_index;
 
     char buf[JACK_PORT_NAME_SIZE];
     char portname[JACK_PORT_NAME_SIZE];
@@ -730,10 +731,10 @@ int JackFreebobDriver::Attach()
         } else {
             printMessage ("Registering capture port %s", buf);
 
-            if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, buf,
+            if (fEngine->PortRegister(fClientControl.fRefNum, buf,
                               JACK_DEFAULT_AUDIO_TYPE,
                               CaptureDriverFlags,
-                              fEngineControl->fBufferSize)) == NO_PORT) {
+                              fEngineControl->fBufferSize, &port_index) < 0) {
                 jack_error("driver: cannot register port for %s", buf);
                 return -1;
             }
@@ -759,10 +760,10 @@ int JackFreebobDriver::Attach()
             printMessage ("Don't register playback port %s", buf);
         } else {
             printMessage ("Registering playback port %s", buf);
-            if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, buf,
+            if (fEngine->PortRegister(fClientControl.fRefNum, buf,
                               JACK_DEFAULT_AUDIO_TYPE,
                               PlaybackDriverFlags,
-                              fEngineControl->fBufferSize)) == NO_PORT) {
+                              fEngineControl->fBufferSize, &port_index) < 0) {
                 jack_error("driver: cannot register port for %s", buf);
                 return -1;
             }
diff --git a/macosx/coreaudio/JackCoreAudioDriver.cpp b/macosx/coreaudio/JackCoreAudioDriver.cpp
index 49a9f5d6..5122feb8 100644
--- a/macosx/coreaudio/JackCoreAudioDriver.cpp
+++ b/macosx/coreaudio/JackCoreAudioDriver.cpp
@@ -27,6 +27,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 #include "JackGlobals.h"
 #include "JackTools.h"
 #include "JackCompilerDeps.h"
+#include "JackLockedEngine.h"
 
 #include <iostream>
 #include <CoreServices/CoreServices.h>
@@ -1642,7 +1643,7 @@ int JackCoreAudioDriver::Attach()
 
         snprintf(name, sizeof(name) - 1, "%s:capture_%d", fClientControl.fName, i + 1);
 
-        if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, CaptureDriverFlags, fEngineControl->fBufferSize)) == NO_PORT) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, CaptureDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error("Cannot register port for %s", name);
             return -1;
         }
@@ -1668,7 +1669,7 @@ int JackCoreAudioDriver::Attach()
 
         snprintf(name, sizeof(name) - 1, "%s:playback_%d", fClientControl.fName, i + 1);
 
-        if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, PlaybackDriverFlags, fEngineControl->fBufferSize)) == NO_PORT) {
+        if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, PlaybackDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
             jack_error("Cannot register port for %s", name);
             return -1;
         }
@@ -1681,7 +1682,7 @@ int JackCoreAudioDriver::Attach()
         if (fWithMonitorPorts) {
             jack_log("Create monitor port");
             snprintf(name, sizeof(name) - 1, "%s:monitor_%u", fClientControl.fName, i + 1);
-            if ((port_index = fGraphManager->AllocatePort(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, MonitorDriverFlags, fEngineControl->fBufferSize)) == NO_PORT) {
+            if (fEngine->PortRegister(fClientControl.fRefNum, name, JACK_DEFAULT_AUDIO_TYPE, MonitorDriverFlags, fEngineControl->fBufferSize, &port_index) < 0) {
                 jack_error("Cannot register monitor port for %s", name);
                 return -1;
             } else {
diff --git a/macosx/coremidi/JackCoreMidiDriver.cpp b/macosx/coremidi/JackCoreMidiDriver.cpp
index 092aaa61..c1470f98 100644
--- a/macosx/coremidi/JackCoreMidiDriver.cpp
+++ b/macosx/coremidi/JackCoreMidiDriver.cpp
@@ -94,9 +94,9 @@ JackCoreMidiDriver::Attach()
     for (int i = 0; i < num_physical_inputs; i++) {
         port_obj = physical_input_ports[i];
         name = port_obj->GetName();
-        index = fGraphManager->AllocatePort(fClientControl.fRefNum, name,
-                                            JACK_DEFAULT_MIDI_TYPE,
-                                            CaptureDriverFlags, buffer_size);
+        fEngine->PortRegister(fClientControl.fRefNum, name,
+                            JACK_DEFAULT_MIDI_TYPE,
+                            CaptureDriverFlags, buffer_size, &index);
         if (index == NO_PORT) {
             jack_error("JackCoreMidiDriver::Attach - cannot register physical "
                        "input port with name '%s'.", name);
@@ -113,9 +113,9 @@ JackCoreMidiDriver::Attach()
     for (int i = 0; i < num_virtual_inputs; i++) {
         port_obj = virtual_input_ports[i];
         name = port_obj->GetName();
-        index = fGraphManager->AllocatePort(fClientControl.fRefNum, name,
-                                            JACK_DEFAULT_MIDI_TYPE,
-                                            CaptureDriverFlags, buffer_size);
+        fEngine->PortRegister(fClientControl.fRefNum, name,
+                            JACK_DEFAULT_MIDI_TYPE,
+                            CaptureDriverFlags, buffer_size, &index);
         if (index == NO_PORT) {
             jack_error("JackCoreMidiDriver::Attach - cannot register virtual "
                        "input port with name '%s'.", name);
@@ -138,9 +138,9 @@ JackCoreMidiDriver::Attach()
     for (int i = 0; i < num_physical_outputs; i++) {
         port_obj = physical_output_ports[i];
         name = port_obj->GetName();
-        index = fGraphManager->AllocatePort(fClientControl.fRefNum, name,
-                                            JACK_DEFAULT_MIDI_TYPE,
-                                            PlaybackDriverFlags, buffer_size);
+        fEngine->PortRegister(fClientControl.fRefNum, name,
+                            JACK_DEFAULT_MIDI_TYPE,
+                            PlaybackDriverFlags, buffer_size, &index);
         if (index == NO_PORT) {
             jack_error("JackCoreMidiDriver::Attach - cannot register physical "
                        "output port with name '%s'.", name);
@@ -157,9 +157,9 @@ JackCoreMidiDriver::Attach()
     for (int i = 0; i < num_virtual_outputs; i++) {
         port_obj = virtual_output_ports[i];
         name = port_obj->GetName();
-        index = fGraphManager->AllocatePort(fClientControl.fRefNum, name,
-                                            JACK_DEFAULT_MIDI_TYPE,
-                                            PlaybackDriverFlags, buffer_size);
+        fEngine->PortRegister(fClientControl.fRefNum, name,
+                            JACK_DEFAULT_MIDI_TYPE,
+                            PlaybackDriverFlags, buffer_size, &index);
         if (index == NO_PORT) {
             jack_error("JackCoreMidiDriver::Attach - cannot register virtual "
                        "output port with name '%s'.", name);
diff --git a/windows/winmme/JackWinMMEDriver.cpp b/windows/winmme/JackWinMMEDriver.cpp
index b05d36e6..58c056b7 100644
--- a/windows/winmme/JackWinMMEDriver.cpp
+++ b/windows/winmme/JackWinMMEDriver.cpp
@@ -74,6 +74,7 @@ JackWinMMEDriver::Attach()
         port->SetAlias(input_port->GetAlias());
         port->SetLatencyRange(JackCaptureLatency, &latency_range);
         fCapturePortList[i] = index;
+        fEngine->NotifyPortRegistration(index, true);
     }
 
     if (! fEngineControl->fSyncMode) {
@@ -99,6 +100,7 @@ JackWinMMEDriver::Attach()
         port->SetAlias(output_port->GetAlias());
         port->SetLatencyRange(JackPlaybackLatency, &latency_range);
         fPlaybackPortList[i] = index;
+        fEngine->NotifyPortRegistration(index, true);
     }
 
     return 0;