Add discovery (mdns) and SNMP nodes

io/mdns/README.md

@@ -0,0 +1,43 @@
+node-red-node-discover
+======================
+
+A <a href="http://nodered.org" target="_new">Node-RED</a> node that uses Bonjour
+ / Avahi to discover local network services such as iTunes libraries, printers, etc.
+
+Prerequisites
+-------------
+
+please read the [install instructions](https://www.npmjs.com/package/mdns) for the underlying npm.
+
+For Debian / Ubuntu this requires installing
+
+    sudo apt-get install libavahi-compat-libdnssd-dev
+
+Install
+-------
+
+Run the following command in the root directory of your Node-RED install
+
+    npm install node-red-node-discover
+
+Usage
+-----
+
+Uses a javascript implenetation of mdns ( mdns-js ) to provide a Bonjour / Avahi
+service discovery capability.
+
+**msg.payload** contains the service object on both arrival and leaving.
+
+**msg.state** contains boolean true or false depending if the service has arrived (true) or gone away (false)..
+
+Within the msg.payload object the most interesting things are:
+
+ * msg.payload.name
+ * msg.payload.interface
+ * msg.payload.port
+ * msg.payload.addresses
+ * msg.payload.txtRecord
+
+For a full list of official service types see [this list](http://www.dns-sd.org/ServiceTypes.html" target="_new).
+
+**Note**: When Node-RED starts you will get a big WARNING message about the Bonjour compatability layer... this is just a warning so don't worry.