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116 lines
4.7 KiB
Markdown
116 lines
4.7 KiB
Markdown
Internet of Things (XEP-0323, -0324, -0325, -0347)
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==================================================
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The Internet of Things (IoT) XEPs are an experimental open standard how XMPP can be used for IoT. They currently consists of
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- XEP-0323 Sensor Data
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- XEP-0324 Provisioning
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- XEP-0325 Control
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- XEP-0326 Concentrators
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- XEP-0347 Discovery
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Smack only supports a subset of the functionality described by the XEPs!
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Thing Builder
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-------------
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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.
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Reading data from things
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------------------------
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For example, we can build a Thing which provides the current temperature with
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```java
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Thing dataThing = Thing.builder().setKey(key).setSerialNumber(sn).setMomentaryReadOutRequestHandler(new ThingMomentaryReadOutRequest() {
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@Override
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public void momentaryReadOutRequest(ThingMomentaryReadOutResult callback) {
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int temp = getCurrentTemperature();
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IoTDataField.IntField field = new IntField("temperature", temp);
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callback.momentaryReadOut(Collections.singletonList(field));
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}
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}).build();
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```
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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.
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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.
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```java
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IoTDataManager iotDataManager = IoTDataManager.getInstanceFor(connection);
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iotDataManager.installThing(thing);
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```
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The data can be read out also by using the `IoTDataManager`:
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```java
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FullJid jid = …
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List<IoTFieldsExtension> values = iotDataManager.requestMomentaryValuesReadOut(jid);
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```
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Now you have to unwrap the `IoTDataField` instances from the `IoTFieldsExtension`. Note that Smack currently only supports a subset of the specified data types.
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Controlling a thing
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-------------------
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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.
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```java
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Thing controlThing = Thing.builder().setKey(key).setSerialNumber(sn).setControlRequestHandler(new ThingControlRequest() {
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@Override
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public void processRequest(Jid from, Collection<SetData> setData) throws XMPPErrorException {
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for (final SetData data : setData) {
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if (!data.getName().equals("light")) continue;
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if (!(data instanceof SetBoolData)) continue;
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SetBoolData boolData = (SetBoolData) data;
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setLight(boolData.getBooleanValue());
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}
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}
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}).build();
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```
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No we have to install this thing into the `IoTControlManager`:
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```java
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IoTControlManager iotControlManager = IoTControlManager.getInstanceFor(connection);
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iotControlManager.installThing(thing);
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```
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The `IoTControlManager` can also be used to control a thing:
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```java
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FullJid jid = …
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SetData setData = new SetBoolData("light", true);
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iotControlManager.setUsingIq(jid, setData);
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```
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Smack currently only supports a subset of the possible data types for set data.
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Discovery
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---------
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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.
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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`.
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```java
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IoTDiscoveryManager iotDiscoveryManager = IoTDiscoveryManager.getInstanceFor(connection);
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iotDiscovyerManager.registerThing(thing);
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```
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The registry will now make the thing known to a broader audience, and available for a potential owner.
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The `IoTDiscoveryManager` can also be used to claim, disown, remove and unregister a thing.
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Provisioning
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------------
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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.
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For example, if you want to befriend another thing:
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```java
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BareJid jid = …
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IoTProvisioningManager iotProvisioningManager = IoTProvisioningManager.getInstanceFor(connection);
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iotProvisioningManager.sendFriendshipRequest(jid);
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```
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