Internet of Things (XEP-0323, -0324, -0325, -0347) ================================================== [Back](index.md) The Internet of Things (IoT) XEPs are an experimental open standard how XMPP can be used for IoT. They currently consists of - XEP-0323 Sensor Data - XEP-0324 Provisioning - XEP-0325 Control - XEP-0326 Concentrators - XEP-0347 Discovery Smack only supports a subset of the functionality described by the XEPs! Thing Builder ------------- The `org.jivesoftware.smackx.iot.Thing` class acts as basic entity representing a single "Thing" which can used to retrieve data from or to send control commands to. `Things` are constructed using a builder API. Reading data from things ------------------------ For example, we can build a Thing which provides the current temperature with ```java Thing dataThing = Thing.builder().setKey(key).setSerialNumber(sn).setMomentaryReadOutRequestHandler(new ThingMomentaryReadOutRequest() { @Override public void momentaryReadOutRequest(ThingMomentaryReadOutResult callback) { int temp = getCurrentTemperature(); IoTDataField.IntField field = new IntField("temperature", temp); callback.momentaryReadOut(Collections.singletonList(field)); } }).build(); ``` While not strictly required, most things are identified via a key and serial number. We also build the thing with a "momentary read out request handler" which when triggered, retrieved the current temperature and reports it back to the requestor. After the `Thing` is build, it needs to be made available so that other entities within the federated XMPP network can use it. Right now, we only intall the Thing in the `IoTDataManager`, which means the thing will act on read out requests but not be managed by a provisioning server. ```java IoTDataManager iotDataManager = IoTDataManager.getInstanceFor(connection); iotDataManager.installThing(thing); ``` The data can be read out also by using the `IoTDataManager`: ```java FullJid jid = … List values = iotDataManager.requestMomentaryValuesReadOut(jid); ``` Now you have to unwrap the `IoTDataField` instances from the `IoTFieldsExtension`. Note that Smack currently only supports a subset of the specified data types. Controlling a thing ------------------- Things can also be controlled, e.g. to turn on a light. Let's create thing which can be used to turn the light on and off. ```java Thing controlThing = Thing.builder().setKey(key).setSerialNumber(sn).setControlRequestHandler(new ThingControlRequest() { @Override public void processRequest(Jid from, Collection setData) throws XMPPErrorException { for (final SetData data : setData) { if (!data.getName().equals("light")) continue; if (!(data instanceof SetBoolData)) continue; SetBoolData boolData = (SetBoolData) data; setLight(boolData.getBooleanValue()); } } }).build(); ``` No we have to install this thing into the `IoTControlManager`: ```java IoTControlManager iotControlManager = IoTControlManager.getInstanceFor(connection); iotControlManager.installThing(thing); ``` The `IoTControlManager` can also be used to control a thing: ```java FullJid jid = … SetData setData = new SetBoolData("light", true); iotControlManager.setUsingIq(jid, setData); ``` Smack currently only supports a subset of the possible data types for set data. Discovery --------- You may wondered how a full JIDs of things can be determined. One approach is using the discovery mechanisms specified in XEP-0347. Smack provides the `IoTDiscoveryManager` as API for this. For example, instead of just installing the previous things in the `IoTDataManager` and/or `IoTControlManager`, we could also use the `IoTDiscoveryManger` to register the thing with a registry. Doing thing also installs the thing in the `IoTDataManager` and the `IoTControlManager`. ```java IoTDiscoveryManager iotDiscoveryManager = IoTDiscoveryManager.getInstanceFor(connection); iotDiscovyerManager.registerThing(thing); ``` The registry will now make the thing known to a broader audience, and available for a potential owner. The `IoTDiscoveryManager` can also be used to claim, disown, remove and unregister a thing. Provisioning ------------ Things can usually only be used by other things if they are friends. Since a thing normally can't decide on its own if an incoming friendship request should be granted or not, we can delegate this decission to a provisioning service. Smack provides the `IoTProvisinoManager` to deal with friendship and provisioning. For example, if you want to befriend another thing: ```java BareJid jid = … IoTProvisioningManager iotProvisioningManager = IoTProvisioningManager.getInstanceFor(connection); iotProvisioningManager.sendFriendshipRequest(jid); ```