Azure Service Bus

Another of the transports available for Cambion makes it able to use Azure Service Bus to send data between instances of Cambion. Cambion uses a pub/sub pattern which requires a dedicated Topic with Subscriptions. Azure Service Bus setup of these, as well as how to set up Azure authentication is not covered by this documentation as Microsoft has documented this on their own website.

Installation

As with other transports, the Azure Service Bus transport for Cambion is also available on NuGet so you can install it using the NuGet Package Manager Console:

Install-Package Whitestone.Cambion.Transport.AzureServiceBus

Usage

Seeing as Cambion uses a pub/sub pattern for its inner workings, you will need an existing Azure Service Bus that supports Topics and Subscriptions. Setting up this in Azure is well documented by Microsoft and is not covered in this documentation.

The Azure Service Bus transport is set up using an extension method for ICambionBuilder. This extension method takes an Action<AzureServiceBusConfig> as the input parameter. The most basic values for this configuration are also minimum required values:

public void ConfigureServices(IServiceCollection services)
{
    services.AddCambion()
        .UseAzureServiceBusTransport(conf =>
        {
            conf.Endpoint = "service-bus-namespace.servicebus.windows.net";
            conf.Topic.Name = "cambion";
            conf.Subscription.Name = "cambion-sub-1";
        });
}

Authentication

Microsoft recommends using Azure AD for authentication towards their services. Because of this, the Azure Service Bus transport for Cambion does not support Shared Access Signatures (SAS).

The default authentication used by this transport is Azure Managed Identity. You can also use Azure Active Directory App Registrations (Client Secret).

When the AzureServiceBusConfig.Authentication configuration setting is null or any of its sub settings are null or empty (as it is by default) Cambion will use Managed Identity to connect to the Azure Service Bus. If you want to use an App Registration instead, fill in appropriate values for all the sub settings.

Additional Settings

The AzureServiceBusConfig object has even more configuration options that could be useful. The following table describes all the configuration options:

Group	Parameter name	Required	Description	Default value
	Endpoint	Yes	The full URI to your Azure Service Bus	null
Topic	Name	Yes	The name of the topic	null
	AutoCreate	No	Automatically create the topic if it does not already exist	false
	AutoDelete	No	Automatically deletes the topic when application exits and the topic doesn’t have any connected subscribers	false
	Details	No	Microsoft’s own class for describing a topic. Optionally used together with AutoCreate for more fine grained control of topic creation options	See below
Subscription	Name	Yes	The name of the subscription	null
	AutoCreate	No	Automatically create the subscription if it does not already exist	false
	AutoDelete	No	Automatically deletes the subscription when application exits	false
	Details	No	Microsoft’s own class for describing a subscription. Optionally used together with AutoCreate for more fine grained control of subscription creation options	See below
Authentication	TenantId	No	The Azure AD Tenant the Azure Service bus is connected to	null
	ClientId	No	The App Registration Client ID	null
	ClientSecret	No	The App Registration Client Secret	null

The Details Property

The Details property of the AzureServiceBusConfig is a Microsoft class with options used for creating a topic or a subscription. Please refer to Microsoft’s documentation (CreateTopicOptions / CreateSubscriptionOptions) for the meaning of each property in these classes.

Note

The Name property on the TopicDescription / SubscriptionDescription will always be overwritten by the transport with the value from the AzureServiceBusConfig.Topic.Name / AzureServiceBusConfig.Topic.Name` properties, so any values you set here will be ignored!