diff --git a/docs/Codecs.md b/docs/Codecs.md
index 9f6070f..00be481 100644
--- a/docs/Codecs.md
+++ b/docs/Codecs.md
@@ -71,6 +71,8 @@ The `init()` function is passed a single object containing initialisation parame
 
    * `params.log` can be used to write to Homebridge's log.
    * `params.config` is the accessory's configuration (as configured in `config.json`). This gives the codec access to the standard configuration settings, and lets it use its own if required.
+   * `params.publish` may be used to publish to MQTT directly
+   * `params.notify` may be used to send MQTT-Thing a property notification
 
 The `init()` function must return an object containing `encode()` and `decode()` functions (as described below). This can be just single `encode()` and `decode()` functions for all properties as above. More commonly a properties map containing property-specific functions is used, as follows:
 
@@ -118,6 +120,24 @@ The `decode`() function is called to decode a message received from MQTT before
 
 The `decode()` function may either return the decoded message, or it may deliver it asynchronously by passing it as a parameter to the provided `output` function. If it does neither, no notification will be passed on to MQTT-Thing.
 
+### `publish( topic, message )`
+
+The `publish()` function provided in `init()`'s `params` may be used to publish a message directly to MQTT.
+
+   * `topic` is the MQTT topic to publish
+   * `message` is the message to publish to MQTT
+
+The message is published directly to MQTT, ignoring any apply function usually with the topic and not passing through the Codec's `encode()` function.
+
+### `notify( property, message )`
+
+The `notify()` function provided in `init()`'s `params` may be used to notify MQTT-Thing of the new value for a property. This will deliver the notification to all internal subscribers to the property. Note that generally a corresponding MQTT 'get' topic must have been configured in order for internal subscribers to exist.
+
+   * `property` is the MQTT-Thing property to update
+   * `message` is the value to be passed to MQTT-Thing
+
+The message is passed directly to MQTT-Thing. It does not pass through any apply function or through the Codec's `decode()` function.
+
 ## Empty Codec
 
 When writing a codec, you may find it helpful to start with the no-op implementation in [`test/empty-codec.js`](../test/empty-codec.js). 
diff --git a/docs/ReleaseNotes.md b/docs/ReleaseNotes.md
index b047ef7..1d5d5ed 100644
--- a/docs/ReleaseNotes.md
+++ b/docs/ReleaseNotes.md
@@ -5,6 +5,10 @@
 
 # Homebridge MQTT-Thing: Release Notes
 
+### Version 1.1.12
++ Extended codecs to support ad hoc property changes and MQTT publishing
++ Codec defaults changed to apply per-function
+
 ### Version 1.1.11
 + Fixed publishing of empty messages configured through config-ui-x in startPub (#253)
 
diff --git a/libs/mqttlib.js b/libs/mqttlib.js
index e82cdf3..5848296 100644
--- a/libs/mqttlib.js
+++ b/libs/mqttlib.js
@@ -13,7 +13,8 @@ var mqttlib = new function() {
     //! Context populated with mqttClient and mqttDispatch.
     this.init = function( ctx ) {
         // MQTT message dispatch
-        let mqttDispatch = ctx.mqttDispatch = {}; // map of topic to function( topic, message ) to handle
+        let mqttDispatch = ctx.mqttDispatch = {}; // map of topic to [ function( topic, message ) ] to handle
+        let propDispatch = ctx.propDispatch = {}; // map of proerty to [ rawhandler( topic, message ) ]
 
         let { config, log } = ctx;
         let logmqtt = config.logMqtt;
@@ -76,9 +77,9 @@ var mqttlib = new function() {
             if (logmqtt) {
                 log("Received MQTT: " + topic + " = " + message);
             }
-            var handlers = mqttDispatch[topic];
+            let handlers = mqttDispatch[topic];
             if (handlers) {
-                for( var i = 0; i < handlers.length; i++ ) {
+                for( let i = 0; i < handlers.length; i++ ) {
                     handlers[ i ]( topic, message );
                 }
             } else {
@@ -97,8 +98,27 @@ var mqttlib = new function() {
                 log( 'Loading codec from ' + codecPath );
                 let codecMod = require( codecPath );
                 if( typeof codecMod.init === "function" ) {
+
+                    // direct publishing
+                    let directPub = function( topic, message ) {
+                        if( config.logMqtt ) {
+                            log( 'Publishing MQTT: ' + topic + ' = ' + message );
+                        }
+                        mqttClient.publish( topic, message.toString(), config.mqttPubOptions );
+                    };
+
+                    // notification by property
+                    let notifyByProp = function( property, message ) {
+                        let handlers = propDispatch[ property ];
+                        if( handlers ) {
+                            for( let i = 0; i < handlers.length; i++ ) {
+                                handlers[ i ]( '_prop-' + property, message );
+                            }
+                        }
+                    };
+                    
                     // initialise codec
-                    let codec = ctx.codec = codecMod.init( { log, config } );
+                    let codec = ctx.codec = codecMod.init( { log, config, publish: directPub, notify: notifyByProp } );
                     if( codec ) {
                         // encode/decode must be functions
                         if( typeof codec.encode !== "function" ) {
@@ -146,7 +166,8 @@ var mqttlib = new function() {
 
     // Subscribe
     this.subscribe = function( ctx, topic, property, handler ) {
-        let { mqttDispatch, log, mqttClient, codec } = ctx;
+        let rawHandler = handler;
+        let { mqttDispatch, log, mqttClient, codec, propDispatch } = ctx;
         if( ! mqttClient ) {
             log( 'ERROR: Call mqttlib.init() before mqttlib.subscribe()' );
             return;
@@ -187,6 +208,22 @@ var mqttlib = new function() {
                 };
             }
         }
+
+        // register property dispatch (codec only)
+        if( codec ) {
+            if( propDispatch.hasOwnProperty( property ) ) {
+                // new handler for existing property
+                propDispatch[ property ].push( rawHandler );
+            } else {
+                // new property
+                propDispatch[ property ] = [ rawHandler ];
+                if( ctx.config.logMqtt ) {
+                    log( 'Avalable codec notification property: ' + property );
+                }
+            }
+        }
+
+        // register MQTT dispatch and subscribe
         if( mqttDispatch.hasOwnProperty( topic ) ) {
             // new handler for existing topic
             mqttDispatch[ topic ].push( handler );
diff --git a/package.json b/package.json
index 3f443de..677fc52 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "homebridge-mqttthing",
-  "version": "1.1.11",
+  "version": "1.1.12",
   "description": "Homebridge plugin supporting various services over MQTT",
   "main": "index.js",
   "scripts": {
diff --git a/test/test-codec.js b/test/test-codec.js
index 0d0f830..8b71550 100644
--- a/test/test-codec.js
+++ b/test/test-codec.js
@@ -15,11 +15,20 @@
  */
 function init( params ) {
     // extract parameters for convenience
-    let { log, config } = params;
+    let { log, config, publish, notify } = params;
 
     setTimeout( () => {
-        log( `Hello from test-codec.js. This is ${config.name}.` );
-    }, 10000 );
+        let msg = `Hello from test-codec.js. This is ${config.name}.`;
+        log( msg );
+
+        // publish a test message
+        publish( 'hello/mqtt', msg );
+
+        // update state
+        notify( 'on', config.onValue || 1 );
+        notify( 'brightness', 50 );
+        notify( 'HSV', '0,100,100' );
+    }, 3000 );
 
     /**
      * Encode message before sending.