Azure Service Bus Pub/Sub Native Integration

This sample shows how to subscribe to events published by an NServiceBus endpoint using the Azure Service Bus API.

Prerequisites

An environment variable named AzureServiceBus_ConnectionString with the connection string for the Azure Service Bus namespace.

Code walk-through

The sample contains three executable projects:

• Publisher: an NServiceBus endpoint that publishes EventOne and EventTwo events.
• NativeSubscriberA: an executable subscribing to the EventOne event published by the Publisher.
• NativeSubscriberB: an executable subscribing to both events published by the Publisher.

Running the sample

1. Start first the NativeSubscriberA and NativeSubscriberB projects. This will create all the necessary publish/subscribe infrastructure in Azure Service Bus, including the event topics.
2. In the Publisher window, press any key to publish an event.
   • The endpoint in the NativeSubscriberA window will receive EventOne.
   • The endpoint in the NativeSubscriberB window will receive both EventOne and EventTwo.

Setting up namespace entities

Each subscriber requires topic subscription(s) to receive the events published by the Publisher. The subscriptions are created on the EventOne or EventTwo topic, which follow the the default topic naming convention used by NServiceBus endpoints.

await client.CreateSubscriptionAsync(new CreateSubscriptionOptions(topicPath, subscriptionName)
{
    LockDuration = TimeSpan.FromMinutes(5),
    EnableDeadLetteringOnFilterEvaluationExceptions = false,
    MaxDeliveryCount = int.MaxValue,
    EnableBatchedOperations = true,
    ForwardTo = forwardTo,
}, new CreateRuleOptions(ruleName, sqlFilter));

Subscription filters

Subscriptions created by NativeSubscriberA and NativeSubscriberB. NativeSubscriberA subscribes to the EventOne events by adding a subscription with the default TrueFilter and forwarding to its input queue:

await TopologyManager.CreateSubscription(
    ConnectionString,
    queueName,
    ruleName:"$default",
    sqlFilter: new TrueRuleFilter(),
    topicPath: "EventOne",
    forwardTo: queueName
    );

The other subscriber creates two subscriptions following the same subscription pattern under both the EventOne and EventTwo topics.