Notification system with p:poll/push

Question

I\'ve tried to implement the basic notification system for a basic social network with p:poll on view layer and a simple NotificationService class

Answer 1

PrimeFaces push supports one or more channels to push. To be able to create private channels for specific reasons; for example per user like in your case, you can create more than one channels. I had used unique ids for this purpose.

Basically, I've implemented a managed bean which is application scoped that handles user channel matching which should be considered. You can maintain it in different ways.

@ManagedBean
@ApplicationScoped
public class ChannelsBean {

    Map<String, String> channels = new HashMap<String, String>();

    public void addChannel(String user, String channel) {
        channels.put(user, channel);
    }

    public String getChannel(String user) {
        return channels.get(user);
    }

}

Then inject this bean in your backing bean which sends notifications.

@ManagedBean
@SessionScoped
public class GrowlBean {

    private String channel;

    @ManagedProperty(value = "#{channelsBean}")
    private ChannelsBean channels;

    private String sendMessageUser;

    private String user;

    @PostConstruct
    public void doPostConstruction() {
        channel = "/" + UUID.randomUUID().toString();
        channels.addChannel(user, channel);
    }

    public void send() {
        PushContext pushContext = PushContextFactory.getDefault().getPushContext();

        pushContext.push(channels.getChannel(sendMessageUser), new FacesMessage("Hi ", user));
    }

    //Getter Setters
}

You should give the channel value to p:socket. Here is the kickoff example of the page;

<p:growl widgetVar="growl" showDetail="true" />  

<h:form>  
    <p:panel header="Growl">  
        <h:panelGrid columns="2">  
            <p:outputLabel for="user" value="User: " />   
            <p:inputText id="user" value="#{growlBean.sendMessageUser}" required="true" />  


        </h:panelGrid>  

        <p:commandButton value="Send" actionListener="#{growlBean.send}" />  
    </p:panel>  
</h:form>  

<p:socket onMessage="handleMessage" channel="#{growlBean.channel}" />  

<script type="text/javascript">  
function handleMessage(facesmessage) {  
    facesmessage.severity = 'info';  

    growl.show([facesmessage]);  
}  
</script>  

For scalability issues, you should maintain the active or inactive channels. You can remove the one which is not in session or inactive for some time. Remove channels by using @PreDestroy annotation when beans are destroying. There is one channel for one user session in my solution.

My suggestion is; do not use usernames explicitly on the pages. It is not good for security reasons.