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Smack/documentation/extensions/iot.md

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Internet of Things (XEP-0323, -0324, -0325, -0347)
==================================================
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<IoTFieldsExtension> 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> 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);
```