Primefaces push - only to specific client - jsf

Question

How can I create some push notification with primefaces p:push only for an entity with ID =1 from my database?
In more detail: I have in my database a table "device". This means every time if a computer / tablet connects to my webapplication a new device will be stored in my database.
I have also a SessionBean for the device. This means a connected device knows "I am device with ID = 1".
Now I would like to send a push notification only to this device with ID = 1
Can anybody help me, please?
Thank you very much.
EDIT:
Bean Classes: NotifyResource and NotifyView
#PushEndpoint("/{macAddress}")
#Singleton
public class NotifyResource {
#PathParam(value = "macAddress")
private String macAddress;
#OnMessage(decoders = JSONDecoder.class, encoders = JSONEncoder.class)
public void onMessage(RemoteEndpoint r, EventBus eventBus) {
System.out.println("pushing to " + macAddress);
}
#RequestScoped
#RequestScoped
public class NotifyView {
#Inject
private DeviceBean deviceBean;
public void send() {
EventBus eventBus = EventBusFactory.getDefault().eventBus();
String macAddress = deviceBean.getDevice().getMacAddress();
byte[] bytesEncoded = Base64.encodeBase64(macAddress .getBytes());
eventBus.publish("/" + new String(bytesEncoded), new FacesMessage("Test", "Tasasas"));
}
}
JSF PAGE
<p:growl widgetVar="growl" showDetail="true" />
<p:socket onMessage="handleMessage" channel="/#{deviceBean.device.macAddress}" autoConnect="true" widgetVar='subscriber'/>
<script type="text/javascript">
function handleMessage(facesmessage) {
facesmessage.severity = 'info';
PF('growl').show([facesmessage]);
}

Answer 1

You can actually define placeholders on your Push Endpoint. Generally speaking, you can always put multiple users in a single push group. By putting each user in the group "/anything/hisOwnId", you make sure, each user has his/her own channel, since the ID is unique...
#PushEndpoint("{macAddress}")
#Singleton
public class PushResource
{
#PathParam(value = "macAddress")
private String macAddress;
#OnMessage(decoders = JSONDecoder.class, encoders = JSONEncoder.class)
public void onMessage(RemoteEndpoint r, EventBus eventBus) {
System.out.println("pushing to " + macAddress);
}
....
}
In your xhtml, you define your p:socket, in this case I've set it NOT to automatically connect.
To connect to the specific channel, the following JavaScript command can be used:
PF('subscriber').connect('/5') /* Id 5 */
With PrimeFaces, you can also execute JavaScript command from backing beans using RequestContext.getCurrentInstance().execute("command");
You could probably auto connect, too, but you have to make sure the user is logged in, to retreive the ID.
<!-- Not sure, if there has to be a forward slash in the beginning -->
<p:socket onMessage="handleMessage" channel="#{currentUser.id}" autoConnect="true" widgetVar='subscriber' />
<script type="text/javascript">
function handleMessage(msg) {
alert('received push');
}
</script>
To push a message to the specific channel (the user id in your case)
private final EventBus eventBus = EventBusFactory.getDefault().eventBus();
// Send message to specific path (Id equals 5)
eventBus.publish("5", pushMessage);
// Send global push message
eventBus.publish(pushMessage);
I've also added the following entry to my web.xml
<servlet>
<servlet-name>PrimePushServlet</servlet-name>
<servlet-class>org.primefaces.push.PushServlet</servlet-class>
<init-param>
<param-name>org.atmosphere.cpr.broadcasterCacheClass</param-name>
<param-value>org.atmosphere.cache.UUIDBroadcasterCache</param-value>
</init-param>
<init-param>
<param-name>org.atmosphere.util.IOUtils.readGetBody</param-name>
<param-value>true</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
<async-supported>true</async-supported>
</servlet>
<servlet-mapping>
<servlet-name>PrimePushServlet</servlet-name>
<url-pattern>/primepush/*</url-pattern>
</servlet-mapping>
You could also take a look at the PrimeFaces Chat Example. The application uses chat rooms as path. Multiple users can be in a single chat room, so all of the users within that specific channel receive the push message.
Passing custom entities
To pass custom entities, rather than just plain Strings or FacesMessages, you have to write your own Encoder/Decoder class.
public class PushMessageDecoder implements Decoder<String, YourEntity>
{
#Override
public PushMessage decode(String s)
{
return (YourEntity) new JSONDecoder().decode(s);
}
}
public class PushMessageEncoder implements Encoder<YourEntity, String>
{
#Override
public String encode(YourEntity message)
{
return new JSONObject(message).toString();
}
}
In your push endpoint, you have to specify your custom encoder/decoder within the #OnMessage annotation.
#OnMessage(decoders = { PushMessageDecoder.class }, encoders = { PushMessageEncoder.class })
Verifying Push
You can pretty easily verify, if your push endpoint is working as expected.
Push a message to the given channel, i.e.
// 56156498494 is the mac address (not sure if special characters work in the path, you may have to encode the mac address).
eventBus.publish("/56156498494", pushMessage);
Now, simply set a break point or make a system.out in your #onMessage function in the push endpoint. You can take a look at the variable annoted with #PathParam and verify, that the value of that variable is actually the channel you wanted to push the message in.
To verify your client side handleMessage function is working and the push message is actually being retreived, simply put a alert('foo'); in your handleMessage function.