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. First, run the Publisher project by itself. This will create all the necessary publish/subscribe infrastructure in Azure Service Bus, including the default bundle-1 topic.
2. Run the projects normally so that all endpoints start.
3. 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 a topic subscription to receive the events published by the Publisher. The subscriptions are created on the bundle-1 topic, which is the default name used by NServiceBus endpoints.

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

Subscription filters

Subscriptions created by NativeSubscriberA and NativeSubscriberB contain a single filtering rule. NativeSubscriberA subscribes to the EventOne events only by specifying a SQL subscription rule (event-one) that matches the event type name stored in the event properties collection:

await TopologyManager.CreateSubscription(
    ConnectionString,
    subscriptionName,
    ruleName: "event-one",
    sqlFilter: new SqlRuleFilter($"[NServiceBus.EnclosedMessageTypes] LIKE '%{typeof(EventOne).FullName}%'")
    );

The other subscriber uses TrueFilter in the all-events rule which ensures that both EventOne and EventTwo events are routed to its subscription.