diff --git a/devstack/plugin.sh b/devstack/plugin.sh
index 4fa5d38..b6c282a 100644
--- a/devstack/plugin.sh
+++ b/devstack/plugin.sh
@@ -23,33 +23,77 @@
 #
 # Environment Configuration
 #
-# AMQP1_SERVICE - identifies the messaging backend to use.  Should be
-#    one of 'qpid' for broker backend, 'qpid-dual' for hybrid router-broker, or
-#    'qpid-hybrid' for keeping Rabbit for notifcations.
-#    @TODO(kgiusti) add qpid-dispatch, etc
+# AMQP1_SERVICE - This plugin can deploy one of several different
+#   message bus configurations.  This variable identifies the message
+#   bus configuration that will be used. Should be one of:
+#     'qpid' - use the qpidd broker for both RPC and Notifications
+#     'qpid-dual' - use qpidd for Notifications, qdrouterd for RPC
+#     'qpid-hybrid' - use rabbitmq for Notifications, qdrouterd for RPC
+#     'external' - use a pre-provisioned message bus.  This prevents
+#       this plugin from creating the message bus.  Instead it assumes
+#       the bus has already been set up and simply connects to it.
+# AMQP1_RPC_TRANSPORT_URL - Transport URL to use for RPC service
+# AMQP1_NOTIFY_TRANSPORT_URL - Transport URL to use for Notification
+#    service.
+#
+# If the above AMQP1_*_TRANSPORT_URL env vars are not defined, this
+# plugin will construct these urls using the following env vars:
+#
 # AMQP1_HOST - the host used to connect to the messaging service.
-#    Defaults to 127.0.0.1
-# AMQP1_{DEFAULT_PORT, NOTIFY_PORT} - the port used to connect to the messaging
-#    service. Defaults to 5672 and 5671.
-# AMQP1_{USERNAME,PASSWORD} - for authentication with AMQP1_HOST
+#    Defaults to $SERVICE_HOST
+# AMQP1_{DEFAULT_PORT, NOTIFY_PORT} - the port used to connect to the
+#    messaging service. AMQP1_NOTIFY_PORT defaults to 5672.
+#    AMQP_DEFAULT_PORT also defaults to 5672 for the 'qpid'
+#    configuration, otherwise 45672 to avoid port# clashes with the
+#    Notification port.
+# AMQP1_{USERNAME,PASSWORD} - for authentication with AMQP1_HOST (optional)
+#
+# The RPC transport url will be defined as:
+# "amqp://$AMQP1_USERNAME:$AMQP1_PASSWORD@$AMQP1_HOST:${AMQP1_DEFAULT_PORT}/"
+#
+# The notify transport url will be defined as:
+# "amqp://$AMQP1_USERNAME:$AMQP1_PASSWORD@$AMQP1_HOST:${AMQP1_NOTIFY_PORT}/"
 #
 
-# builds default transport url string
-function _get_amqp1_default_transport_url {
-    if [ -z "$AMQP1_USERNAME" ]; then
-        echo "amqp://$AMQP1_HOST:${AMQP1_DEFAULT_PORT}/"
+# parse URL, extracting host, port, username, password
+function _parse_transport_url {
+    local uphp    # user+password+host+port
+    local user    # username
+    local passwd  # password
+    local hostport  # host+port
+    local host    # hostname
+    local port    # port #
+
+    # extract [user:pass@]host:port
+    uphp=$(echo $1 | sed -e "s#^[^:]*://\([^/]*\).*#\1#")
+    # parse out username + password if present:
+    user=""
+    passwd=""
+    if [[ "$uphp" =~ .+@.+ ]]; then
+        local passhostport
+        user=$(echo $uphp | sed -e "s#^\([^:]*\).*#\1#")
+        passhostport=$(echo $uphp | sed -e "s#$user:##")
+        passwd=$(echo $passhostport | sed -e "s#^\([^@]*\).*#\1#")
+        hostport=$(echo $passhostport | sed -e "s#$passwd@##")
     else
-        echo "amqp://$AMQP1_USERNAME:$AMQP1_PASSWORD@$AMQP1_HOST:${AMQP1_DEFAULT_PORT}/"
+        hostport=$uphp
     fi
+    host=$(echo $hostport | cut -d: -f1)
+    port=$(echo $hostport | cut -d: -f2)
+
+    # field 1   2     3     4
+    echo "$host $port $user $passwd"
 }
 
-# builds notify transport url string
+
+# default transport url string
+function _get_amqp1_default_transport_url {
+    echo "$AMQP1_RPC_TRANSPORT_URL"
+}
+
+# notify transport url string
 function _get_amqp1_notify_transport_url {
-    if [ -z "$AMQP1_USERNAME" ]; then
-        echo "amqp://$AMQP1_HOST:${AMQP1_NOTIFY_PORT}/"
-    else
-        echo "amqp://$AMQP1_USERNAME:$AMQP1_PASSWORD@$AMQP1_HOST:${AMQP1_NOTIFY_PORT}/"
-    fi
+    echo "$AMQP1_NOTIFY_TRANSPORT_URL"
 }
 
 # install packages necessary for support of the oslo.messaging AMQP
@@ -81,6 +125,9 @@ function _remove_pyngus {
 # Set up the various configuration files used by the qpidd broker
 function _configure_qpid {
 
+    local url
+    url=$(_parse_transport_url $1)
+
     # the location of the configuration files have changed since qpidd 0.14
     local qpid_conf_file
     if [ -e /etc/qpid/qpidd.conf ]; then
@@ -95,7 +142,8 @@ function _configure_qpid {
     sudo chmod o+r $qpid_conf_file
 
     # force the ACL file to a known location
-    local qpid_acl_file=/etc/qpid/qpidd.acl
+    local qpid_acl_file
+    qpid_acl_file=/etc/qpid/qpidd.acl
     if [ ! -e $qpid_acl_file ]; then
         sudo mkdir -p -m 755 `dirname $qpid_acl_file`
         sudo touch $qpid_acl_file
@@ -103,12 +151,9 @@ function _configure_qpid {
     fi
     echo "acl-file=$qpid_acl_file" | sudo tee $qpid_conf_file
 
-    # map broker port for dual backend config
-    if [ "$AMQP1_SERVICE" == "qpid-dual" ]; then
-        echo "port=${AMQP1_NOTIFY_PORT}" | sudo tee --append $qpid_conf_file
-    fi
-
-    if [ -z "$AMQP1_USERNAME" ]; then
+    local username
+    username=$(echo "$url" | cut -d' ' -f3)
+    if [ -z "$username" ]; then
         # no QPID user configured, so disable authentication
         # and access control
         echo "auth=no" | sudo tee --append $qpid_conf_file
@@ -117,19 +162,22 @@ acl allow all all
 EOF
     else
         # Configure qpidd to use PLAIN authentication, and add
-        # AMQP1_USERNAME to the ACL:
+        # $username to the ACL:
         echo "auth=yes" | sudo tee --append $qpid_conf_file
-        if [ -z "$AMQP1_PASSWORD" ]; then
-            read_password AMQP1_PASSWORD "ENTER A PASSWORD FOR QPID USER $AMQP1_USERNAME"
+        local passwd
+        passwd=$(echo "$url" | cut -d' ' -f4)
+        if [ -z "$passwd" ]; then
+            read_password password "ENTER A PASSWORD FOR QPID USER $username"
         fi
-        # Create ACL to allow $AMQP1_USERNAME full access
+        # Create ACL to allow $username full access
         cat <<EOF | sudo tee $qpid_acl_file
-group admin ${AMQP1_USERNAME}@QPID
+group admin ${username}@QPID
 acl allow admin all
 acl deny all all
 EOF
         # Add user to SASL database
-        local sasl_conf_file=/etc/sasl2/qpidd.conf
+        local sasl_conf_file
+        sasl_conf_file=/etc/sasl2/qpidd.conf
         cat <<EOF | sudo tee $sasl_conf_file
 pwcheck_method: auxprop
 auxprop_plugin: sasldb
@@ -143,7 +191,7 @@ EOF
         if [ ! -e $sasl_db ]; then
             sudo mkdir -p -m 755 `dirname $sasl_db`
         fi
-        echo $AMQP1_PASSWORD | sudo saslpasswd2 -c -p -f $sasl_db -u QPID $AMQP1_USERNAME
+        echo $passwd | sudo saslpasswd2 -c -p -f $sasl_db -u QPID $username
         sudo chmod o+r $sasl_db
     fi
 
@@ -154,7 +202,8 @@ EOF
     if ! $QPIDD --help | grep -q "queue-patterns"; then
         exit_distro_not_supported "qpidd with AMQP 1.0 support"
     fi
-    local log_file=$LOGDIR/qpidd.log
+    local log_file
+    log_file=$LOGDIR/qpidd.log
     cat <<EOF | sudo tee --append $qpid_conf_file
 queue-patterns=exclusive
 queue-patterns=unicast
@@ -180,6 +229,9 @@ EOF
 # Set up the various configuration files used by the qpid-dispatch-router (qdr)
 function _configure_qdr {
 
+    local url
+    url=$(_parse_transport_url $1)
+
     # the location of the configuration is /etc/qpid-dispatch
     local qdr_conf_file
     if [ -e /etc/qpid-dispatch/qdrouterd.conf ]; then
@@ -207,13 +259,17 @@ router {
 EOF
 
     # Create a listener for incoming connect to the router
+    local port
+    port=$(echo "$url" | cut -d' ' -f2)
     cat <<EOF | sudo tee --append $qdr_conf_file
 listener {
     addr: 0.0.0.0
-    port: ${AMQP1_DEFAULT_PORT}
+    port: ${port}
     role: normal
 EOF
-    if [ -z "$AMQP1_USERNAME" ]; then
+    local username
+    username=$(echo "$url" | cut -d' ' -f3)
+    if [ -z "$username" ]; then
         #no user configured, so disable authentication
         cat <<EOF | sudo tee --append $qdr_conf_file
     authenticatePeer: no
@@ -222,8 +278,10 @@ EOF
 EOF
     else
         # configure to use PLAIN authentication
-        if [ -z "$AMQP1_PASSWORD" ]; then
-            read_password AMQP1_PASSWORD "ENTER A PASSWORD FOR QPID DISPATCH USER $AMQP1_USERNAME"
+        local passwd
+        passwd=$(echo "$url" | cut -d' ' -f4)
+        if [ -z "$passwd" ]; then
+            read_password passwd "ENTER A PASSWORD FOR QPID DISPATCH USER $username"
         fi
         cat <<EOF | sudo tee --append $qdr_conf_file
     authenticatePeer: yes
@@ -231,7 +289,8 @@ EOF
 
 EOF
         # Add user to SASL database
-        local sasl_conf_file=/etc/sasl2/qdrouterd.conf
+        local sasl_conf_file
+        sasl_conf_file=/etc/sasl2/qdrouterd.conf
         cat <<EOF | sudo tee $sasl_conf_file
 pwcheck_method: auxprop
 auxprop_plugin: sasldb
@@ -244,7 +303,7 @@ EOF
         if [ ! -e $sasl_db ]; then
             sudo mkdir -p -m 755 `dirname $sasl_db`
         fi
-        echo $AMQP1_PASSWORD | sudo saslpasswd2 -c -p -f $sasl_db $AMQP1_USERNAME
+        echo $passwd | sudo saslpasswd2 -c -p -f $sasl_db $username
         sudo chmod o+r $sasl_db
     fi
 
@@ -297,8 +356,8 @@ address {
 
 EOF
 
-    local log_file=$LOGDIR/qdrouterd.log
-
+    local log_file
+    log_file=$LOGDIR/qdrouterd.log
     sudo touch $log_file
     sudo chmod a+rw $log_file  # qdrouterd user can write to it
 
@@ -319,39 +378,35 @@ EOF
 # (qpidd broker and optionally dispatch-router for hybrid)
 function _install_amqp1_backend {
 
+    local qdrouterd_package
+    local qpidd_package
     if is_fedora; then
         # expects epel is already added to the yum repos
         install_package cyrus-sasl-lib
         install_package cyrus-sasl-plain
-        if [ "$AMQP1_SERVICE" != "qpid-hybrid" ]; then
-            install_package qpid-cpp-server
-        fi
-        if [ "$AMQP1_SERVICE" != "qpid" ]; then
-            install_package qpid-dispatch-router
-        fi
+        qdrouterd_package="qpid-dispatch-router"
+        qpidd_package="qpid-cpp-server"
     elif is_ubuntu; then
         install_package sasl2-bin
         # newer qpidd and proton only available via the qpid PPA
         sudo add-apt-repository -y ppa:qpid/released
-        #sudo apt-get update
         REPOS_UPDATED=False
         update_package_repo
-        if [ "$AMQP1_SERVICE" != "qpid-hybrid" ]; then
-            install_package qpidd
-        fi
-        if [ "$AMQP1_SERVICE" != "qpid" ]; then
-            install_package qdrouterd
-        fi
+        qdrouterd_package="qdrouterd"
+        qpidd_package="qpidd"
     else
         exit_distro_not_supported "amqp1 qpid installation"
     fi
 
     _install_pyngus
-    if [ "$AMQP1_SERVICE" != "qpid-hybrid" ]; then
-        _configure_qpid
+
+    if [ "$AMQP1_RPC" == "qdrouterd" ]; then
+        install_package $qdrouterd_package
+        _configure_qdr $AMQP1_RPC_TRANSPORT_URL
     fi
-    if [ "$AMQP1_SERVICE" != "qpid" ]; then
-        _configure_qdr
+    if [ "$AMQP1_NOTIFY" == "qpidd" ]; then
+        install_package $qpidd_package
+        _configure_qpid $AMQP1_NOTIFY_TRANSPORT_URL
     fi
 }
 
@@ -359,36 +414,30 @@ function _install_amqp1_backend {
 function _start_amqp1_backend {
     echo_summary "Starting amqp1 backends"
     # restart, since qpid* may already be running
-    if [ "$AMQP1_SERVICE" != "qpid-hybrid" ]; then
-        restart_service qpidd
-    fi
-    if [ "$AMQP1_SERVICE" != "qpid" ]; then
+    if [ "$AMQP1_RPC" == "qdrouterd" ]; then
         restart_service qdrouterd
     fi
+    if [ "$AMQP1_NOTIFY" == "qpidd" ]; then
+        restart_service qpidd
+    fi
 }
 
 
 function _cleanup_amqp1_backend {
     if is_fedora; then
-        if [ "$AMQP1_SERVICE" != "qpid-hybrid" ]; then
-            uninstall_package qpid-cpp-server
-        fi
-        if [ "$AMQP1_SERVICE" != "qpid" ]; then
+        if [ "$AMQP1_RPC" == "qdrouterd" ]; then
             uninstall_package qpid-dispatch-router
         fi
-        # TODO(kgiusti) can we pull these, or will that break other
-        # packages that depend on them?
-
-        # install_package cyrus_sasl_lib
-        # install_package cyrus_sasl_plain
-    elif is_ubuntu; then
-        if [ "$AMQP1_SERVICE" != "qpid-hybrid" ]; then
-            uninstall_package qpidd
+        if [ "$AMQP1_NOTIFY" == "qpidd" ]; then
+            uninstall_package qpid-cpp-server
         fi
-        if [ "$AMQP1_SERVICE" != "qpid" ]; then
+    elif is_ubuntu; then
+        if [ "$AMQP1_RPC" == "qdrouterd" ]; then
             uninstall_package qdrouterd
         fi
-        # install_package sasl2-bin
+        if [ "$AMQP1_NOTIFY" == "qpidd" ]; then
+            uninstall_package qpidd
+        fi
     else
         exit_distro_not_supported "amqp1 qpid installation"
     fi
@@ -399,28 +448,70 @@ function _cleanup_amqp1_backend {
 
 # iniset configuration for amqp rpc_backend
 function _iniset_amqp1_backend {
-    local package=$1
-    local file=$2
-    local section=${3:-DEFAULT}
+    local package
+    local file
+    local section
 
-    if [ "$AMQP1_SERVICE" == "qpid-dual" ]; then
-        iniset $file $section transport_url $(get_transport_url)
-        iniset $file oslo_messaging_notifications transport_url $(_get_amqp1_notify_transport_url)
-    elif [ "$AMQP1_SERVICE" == "qpid-hybrid" ]; then
-        iniset $file $section transport_url $(get_transport_url)
+    package=$1
+    file=$2
+    section=${3:-DEFAULT}
+
+    iniset $file $section transport_url $(get_transport_url)
+    if [ "$AMQP1_NOTIFY" == "rabbit" ]; then
         iniset $file oslo_messaging_notifications transport_url $(_get_rabbit_transport_url)
     else
-        iniset $file $section transport_url $(get_transport_url)
+        iniset $file oslo_messaging_notifications transport_url $(_get_amqp1_notify_transport_url)
     fi
 }
 
 
 if is_service_enabled amqp1; then
-    # @TODO (ansmith) check is for qdr or qpid for now
-    if [[ "$AMQP1_SERVICE" != "qpid" && "$AMQP1_SERVICE" != "qpid-dual" && "$AMQP1_SERVICE" != "qpid-hybrid" ]]; then
-        die $LINENO "AMQP 1.0 requires qpid, qpid-dual or qpid-hybrid - $AMQP1_SERVICE not supported"
+
+    # for backward compatibility - generate the transport urls from the old env vars if not set
+    if [[ -z "$AMQP1_RPC_TRANSPORT_URL" ]]; then
+        AMQP1_DEFAULT_PORT=${AMQP1_DEFAULT_PORT:=$([[ "$AMQP1_SERVICE" == "qpid" ]] && echo 5672 || echo 45672)}
+        if [ -n "$AMQP1_USERNAME" ]; then
+            AMQP1_RPC_TRANSPORT_URL="amqp://$AMQP1_USERNAME:$AMQP1_PASSWORD@$AMQP1_HOST:$AMQP1_DEFAULT_PORT"
+        else
+            AMQP1_RPC_TRANSPORT_URL="amqp://$AMQP1_HOST:$AMQP1_DEFAULT_PORT"
+        fi
     fi
 
+    if [[ -z "$AMQP1_NOTIFY_TRANSPORT_URL" ]]; then
+        AMQP1_NOTIFY_PORT=${AMQP1_NOTIFY_PORT:=5672}
+        if [ -n "$AMQP1_USERNAME" ]; then
+            AMQP1_NOTIFY_TRANSPORT_URL="amqp://$AMQP1_USERNAME:$AMQP1_PASSWORD@$AMQP1_HOST:$AMQP1_NOTIFY_PORT"
+        else
+            AMQP1_NOTIFY_TRANSPORT_URL="amqp://$AMQP1_HOST:$AMQP1_NOTIFY_PORT"
+        fi
+    fi
+
+    case $AMQP1_SERVICE in
+        "qpid")
+            # Use qpidd for both notifications and RPC messages
+            AMQP1_RPC="qpidd"
+            AMQP1_NOTIFY="qpidd"
+            ;;
+        "qpid-dual")
+            # Use qpidd for notifications and qdrouterd for RPC messages
+            AMQP1_RPC="qdrouterd"
+            AMQP1_NOTIFY="qpidd"
+            ;;
+        "qpid-hybrid")
+            # Use rabbitmq for notifications and qdrouterd for RPC messages
+            AMQP1_RPC="qdrouterd"
+            AMQP1_NOTIFY="rabbit"
+            ;;
+        "external")
+            # Use a pre-provisioned message bus @ AMQP1_NOTIFY/RPC_TRANSPORT_URLs
+            AMQP1_RPC="external"
+            AMQP1_NOTIFY="external"
+            ;;
+        *)
+            die $LINENO "Set AMQP1_SERVICE to one of: qpid, qpid-dual, qpid-hybrid or external - $AMQP1_SERVICE not supported"
+            ;;
+    esac
+
     # Save rabbit get_transport_url for notifications if necessary
     if [ ! $(type -t _get_rabbit_transport_url) ]; then
         get_transport_url_definition=$(declare -f get_transport_url)
@@ -439,20 +530,6 @@ if is_service_enabled amqp1; then
     }
     export -f iniset_rpc_backend
     export -f get_transport_url
-fi
-
-
-# check for amqp1 service
-if is_service_enabled amqp1; then
-
-    if [ "$AMQP1_SERVICE" != "qpid-hybrid" ]; then
-        available_port=5672
-    else
-        available_port=15672
-    fi
-
-    AMQP1_DEFAULT_PORT=${AMQP1_DEFAULT_PORT:=$available_port}
-    AMQP1_NOTIFY_PORT=${AMQP1_NOTIFY_PORT:=5671}
 
     if [[ "$1" == "stack" && "$2" == "pre-install" ]]; then
         # nothing needed here