Publish-Subscribe

Tianming GUO

RICM5

14/11/2014

1.      PUB-SUB Introduction
2.     Protocols & API
3.     PubSub-as-a-Service Providers

4.     Démonstration

• Publisher(Editeur)
• Mediator(Médiateur)
• Subscriber(Abonné)

1. PUB-sub Introduction

RÔLEs

Publisher

Mediator

Subscriber

Envoyer les changement

Registrer l'abonnement

Recevoir l'événement

Filtrer l'événement

Routing

Envoyer les abonnement avec "Topic"

Publisher_1

Publisher_2

Mediator

Subscriber_1

Subscriber_2

Subscriber_3

1. pub-sub Introduction

caractéristique

• Content-based routing
• TCP /UDP/Multicast UDP /Broadcast (in LAN)/mix
• LAN/WAN
• Realtime / Non
• QoS / Non
• Centralisé/Distribué 
• Atomicité
• Médiateur/Direct
• One/many to one/many

1. pub-sub Introduction

2. PROTOCOLS & API

OSGi Event-Admin service -- Apache felix

Deux rôles:

• Event Publisher
• Event Handler (ou Subscriber)

Deux attributs:

• Topic : "org/osgi/framework/FrameworkEvent/STARTED"

"org/osgi/framework/BundleEvent/ERROR"

• Event Subscriber "properties": Décrire l'événement

Event reportGeneratedEvent = new Event("com/acme/reportgenerator/GENERATED", properties);

public void reportGenerated(Report report, BundleContext context)
    {
        ServiceReference ref = context.getServiceReference(EventAdmin.class.getName());
        if (ref != null)
        {
            EventAdmin eventAdmin = (EventAdmin) context.getService(ref);
            
            Dictionary properties = new Hashtable();
            properties.put("title", report.getTitle());
            properties.put("path" , report.getAbsolutePath());
            properties.put("time", System.currentTimeMillis());
            
            Event reportGeneratedEvent = new Event("com/acme/reportgenerator/GENERATED", properties);
            
            eventAdmin.sendEvent(reportGeneratedEvent);
        }
    }

2. PROTOCOLS & API

OSGi Event-Admin service -- Apache felix

Créer un Serveur(synchrone) avec Topic: "com/acme/reportgenerator/GENERATED"

2. PROTOCOLS & API

OSGi Event-Admin service -- Apache felix

        String[] topics = new String[] {
            "com/acme/reportgenerator/GENERATED"
        };
        
        Dictionary props = new Hashtable();
        props.put(EventConstants.EVENT_TOPIC, topics);
        props.put(EventConstants.EVENT_FILTER, "(title=samplereport)");
        bundleContext.registerService(EventHandler.class.getName(), new ReportEventHandler() , props);

public class ReportEventHandler implements EventHandler
{
    public void handleEvent(Event event)
    {
        String reportTitle = (String) event.getProperty("title");
        String reportPath = (String) event.getProperty("path");
        
        sendReportByEmail(reportTitle, reportPath);
    }

Créer un EventHandler

Registrer un EventHandler(avec filtre)

2. PROTOCOLS & API

AMQP (RabbitMQ)

Etape 1 : Exchange

1.1  Choisir un type d'échange : direct, topic, headers, fanout

channel.exchange_declare(exchange='logs',
                         type='fanout')

2. PROTOCOLS & API

AMQP (RabbitMQ)

Etape 2 : Binding

channel.queue_bind(exchange='logs',
                   queue=result.method.queue)

Etape 3 : Commencer à envoyer

2. PROTOCOLS & API

PUBSUBHUBBUB - Google

Publisher - Hub - Subscriber

2. PROTOCOLS & API

Upnp, MQTT, ROS, RTPS

MQTT : Publisher + Server + Subscriber

UPNP : General Event Notification Architecture

• Noms de variable d'état
• Valeurs de variable

ROS : Robot Operating System -- Envoies des événements

RTPS : Real-Time Publish-Subscribe, basé sur UDP

3. PUBSUB-AS-A-SERVICE PROVIDERS

PUBNub

60 + languages et plate-forme de développement dans ses SDKs

3. PUBSUB-AS-A-SERVICE PROVIDERS

PUBNub

Instancier le PubNub

<!-- Include the PubNub Library -->
<script src="https://cdn.pubnub.com/pubnub.min.js"></script>
 
<!-- Instantiate PubNub -->
<script type="text/javascript">
 
  var PUBNUB_demo = PUBNUB.init({
    publish_key: 'demo',
    subscribe_key: 'demo'
  });
  
</script>

PUBNub

3. PUBSUB-AS-A-SERVICE PROVIDERS

//Subscribe to the demo_tutorial channel
PUBNUB_demo.subscribe({
  channel: 'demo_tutorial',
  message: function(m){console.log(m)}
});

Subscribe

// Publish a simple message to the demo_tutorial channel
PUBNUB_demo.publish({
    channel: 'demo_tutorial',
    message: {"text":"Hey!"}
 });

Publish

4. Démonstration

PUBNub