# Azure Functions with Azure Service Bus (In Process) > [!WARNING] > **NServiceBus.AzureFunctions.InProcess.ServiceBus component has been sunset** > > Microsoft announced that .NET 8 will be [the last release supporting the in-process hosting model](https://techcommunity.microsoft.com/t5/apps-on-azure-blog/net-on-azure-functions-august-2023-roadmap-update/ba-p/3910098). > We will continue to provide support and address critical fixes during the sunset period, but no new features will be added. > New projects should use the [isolated worker model](/nservicebus/hosting/azure-functions-service-bus/index.md) instead. Follow [these instructions](/nservicebus/upgrades/azure-functions-service-bus-in-process-isolated-worker.md) to migrate. > For information on the date when this component will stop receiving any update check our [support policy page](/nservicebus/upgrades/all-versions.md#host-packages-nservicebus-azurefunctions-inprocess-servicebus). Host NServiceBus endpoints with [Azure Functions](https://learn.microsoft.com/en-us/azure/azure-functions/) and [Azure Service Bus](https://azure.microsoft.com/en-us/services/service-bus/) triggers. ## Basic usage ### Endpoint configuration NServiceBus can be registered and configured on the host builder using the `UseNServiceBus` extension method in the startup class: ```cs [assembly: FunctionsStartup(typeof(Startup))] [assembly: NServiceBusTriggerFunction("MyFunctionsEndpoint")] class Startup : FunctionsStartup { public override void Configure(IFunctionsHostBuilder builder) { builder.UseNServiceBus(); } } ``` Additional configuration settings are retrieved from environment variables. See the [configuration section](#configuration) for further details. All configuration settings can also be configured directly via code: ```cs class Startup : FunctionsStartup { public override void Configure(IFunctionsHostBuilder builder) { builder.UseNServiceBus(configuration => { var transport = configuration.Transport; // Configure transport }); } } ``` Any services registered via the `IFunctionsHostBuilder` will be available to message handlers via dependency injection. The startup class must be declared via the `FunctionStartup` attribute: `[assembly: FunctionsStartup(typeof(Startup))]`. ### Azure Function queue trigger for NServiceBus The Azure Function trigger for NServiceBus is auto-generated by specifying the logical endpoint name using a custom assembly attribute: ```csharp [assembly: NServiceBusTriggerFunction("MyFunctionsEndpoint")] ``` The attribute will generate the trigger function required for NServiceBus: > [!NOTE] > An invalid endpoint name will generate an `NSBFUNC003` error with the message `Endpoint name is invalid and cannot be used to generate trigger function`. #### Overriding the trigger function name The trigger function name is auto-generated by default. To customize the function name, the `NServiceBusTriggerFunction` attribute can be provided with an additional parameter to set the function name: ```txt [assembly: NServiceBusTriggerFunctionAttribute(EndpointName: "MyFunctionsEndpoint", TriggerFunctionName: "MyTriggerFunction")] ``` > [!NOTE] > An invalid trigger function name will generate an `NSBFUNC004` error with the message `Trigger function name is invalid and cannot be used to generate trigger function`. #### Customizing triggers The Azure Service Bus trigger can be declared manually instead of relying on the auto-generated trigger. See the article on [custom Azure Functions triggers](/nservicebus/hosting/azure-functions-service-bus/in-process/custom-triggers.md) for more information. ### Dispatching outside a message handler Triggering a message using HTTP function: ```cs public class HttpSender { readonly IFunctionEndpoint functionEndpoint; public HttpSender(IFunctionEndpoint functionEndpoint) { this.functionEndpoint = functionEndpoint; } [FunctionName("HttpSender")] public async Task Run( [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest request, ExecutionContext executionContext, ILogger logger) { logger.LogInformation("C# HTTP trigger function received a request."); var sendOptions = new SendOptions(); sendOptions.RouteToThisEndpoint(); await functionEndpoint.Send(new TriggerMessage(), sendOptions, executionContext, logger); return new OkObjectResult($"{nameof(TriggerMessage)} sent."); } } ``` ## Transport configuration constraints and limitations The configuration API exposes NServiceBus transport configuration options via the `configuration.Transport` property to allow customization. However, not all options will be applicable for execution within Azure Functions (for more details, see [analysers](analyzers.md)). Concurrency-related settings are controlled via the Azure Function `host.json` configuration file. See [Concurrency in Azure Functions](https://learn.microsoft.com/en-us/azure/azure-functions/functions-concurrency#service-bus) for details. ## Message consistency NServiceBus can provide transactional consistency between incoming and outgoing messages: ```txt [assembly: NServiceBusTriggerFunction("MyEndpoint", SendsAtomicWithReceive = true)] ``` This is equivalent to the [`SendsAtomicWithReceive`](/transports/transactions.md#transaction-modes-transport-transaction-sends-atomic-with-receive) transport transaction mode. By default, transactional consistency is disabled, providing the same transport guarantees as the [`ReceiveOnly`](/transports/transactions.md#transaction-modes-transport-transaction-receive-only) transport transaction mode. For more information on configuring message consistency using custom triggers, refer to the [custom Azure Functions triggers](/nservicebus/hosting/azure-functions-service-bus/in-process/custom-triggers.md) documentation. > [!NOTE] > Microsoft.Azure.WebJobs.Extensions.ServiceBus Version 5 requires [`EnableCrossEntityTransactions`](https://learn.microsoft.com/en-us/dotnet/api/microsoft.azure.webjobs.servicebus.servicebusoptions.enablecrossentitytransactions) to be enabled in order to support sends atomic with receive. > > This can be done by adding the following to `host.json`: > > ``` > "extensions": { > "ServiceBus": { > "EnableCrossEntityTransactions": true > } > } > ``` ## Configuration `ServiceBusTriggeredEndpointConfiguration` loads certain configuration values from the Azure Function host environment in the following order: - `IConfiguration` passed in via the constructor - Environment variables ### ServiceBus connection When using the `NServiceBusTriggerAttribute`, the connection to Azure Service Bus can be configured in multiple ways: - Using just a `` key, with the value set to the connection string for the ServiceBus namespace to connect to. - Using a `__fullyQualifiedNamespace` along with other connection properties prefixed by the same ``, as specified in the [Identity Based Connections](https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference?tabs=blob&pivots=programming-language-csharp#common-properties-for-identity-based-connections) for Azure Functions. If both a connection string and Identity Based connection values are specified, the connection string will take precedence. The default `` or `` is `AzureWebJobsServiceBus`, however an alternate value can be supplied to the `Connection` property on the `NServiceBusTriggerAttribute` Example of a connection string based connection: ```json { "IsEncrypted": false, "Values": { ... "AzureWebJobsServiceBus": "Endpoint=sb://.servicebus.windows.net/;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=", } } ``` Example of an Identity Based connection: ```json { "IsEncrypted": false, "Values": { ... "MyConnectionName__fullyQualifiedNamespace": ".servicebus.windows.net", "MyConnectionName__tenantId": "00000000-0000-0000-0000-000000000000", "MyConnectionName__clientId": "00000000-0000-0000-0000-000000000000", "MyConnectionName__clientSecret": "" } } ``` ```txt [assembly: NServiceBusTriggerFunction("WorkerDemoEndpoint", Connection = "MyConnectionName")] ``` ### Other Configuration | Key | Value | Notes | |---------------------------------|------------|-----------| | `ENDPOINT_NAME` | The name of the NServiceBus endpoint to host | A value can be provided directly to the constructor. | | `PARTICULARSOFTWARE_LICENSE` | The NServiceBus license | Can also be provided via `serviceBusTriggeredEndpointConfig.EndpointConfiguration.License(...)` or via `NSERVICEBUS_LICENSE` environment variable for backward compatibility reasons. | | `WEBSITE_SITE_NAME` | The name of the Azure Function app. Provided when hosting the function in Azure. | Used to set the NServiceBus [host identifier](/nservicebus/hosting/override-hostid.md). Local machine name is used if not set. | For local development, use `local.settings.json`. In Azure, specify a Function setting using the environment variable as the key. ```json { "IsEncrypted": false, "Values": { ... "PARTICULARSOFTWARE_LICENSE": ". . ." } } ``` ### Custom diagnostics [NServiceBus startup diagnostics](/nservicebus/hosting/startup-diagnostics.md) are disabled by default when using Azure Functions. Diagnostics can be written to the logs via the following snippet: ```cs public override void Configure(IFunctionsHostBuilder builder) { builder.UseNServiceBus(configuration => { configuration.LogDiagnostics(); }); } ``` Diagnostics data will be written with logger identification `StartupDiagnostics` with log level *Informational*. ### Error queue For recoverability to move the continuously failing messages to the error queue rather than to the Azure Service Bus dead-letter queue, the error queue must be created in advance and configured using the following API: ```cs class EnableDiagnosticsOnStartup : FunctionsStartup { public override void Configure(IFunctionsHostBuilder builder) { builder.UseNServiceBus(configuration => { configuration.AdvancedConfiguration.SendFailedMessagesTo("error"); }); } } ``` ## Preparing the Azure Service Bus namespace Function endpoints cannot create their own queues or other infrastructure in the Azure Service Bus namespace. Use the [`asb-transport` command line (CLI) tool](/transports/azure-service-bus/operational-scripting.md) to provision the entities in the namespace for the Function endpoint. ### Creating the endpoint queue ```txt asb-transport endpoint create ``` See the [full documentation](/transports/azure-service-bus/operational-scripting.md#available-commands-asb-transport-endpoint-create) for the `asb-transport endpoint create` command for more details. > [!WARNING] > If the `asb-tranport` command-line tool is not used to create the queue, it is recommended to set the `MaxDeliveryCount` setting to the maximum value. ### Subscribing to events ```txt asb-transport endpoint subscribe ``` See the [full documentation](/transports/azure-service-bus/operational-scripting.md#available-commands-asb-transport-endpoint-subscribe) for the `asb-transport endpoint subscribe` command for more details. ### Topology configuration The [default topology](/transports/azure-service-bus/topology.md) (using topic-per-event approach) can be overridden by adding topology options to the Application configuration. The functions integration looks for either topology options placed into `AzureServiceBus:TopologyOptions` or `AzureServiceBus:MigrationTopologyOptions` for migration scenarios. ```cs class Startup : FunctionsStartup { public override void Configure(IFunctionsHostBuilder builder) { builder.UseNServiceBus(); } public override void ConfigureAppConfiguration(IFunctionsConfigurationBuilder builder) { builder.ConfigurationBuilder.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true); } } ``` Using the default topology ```json { "AzureServiceBus": { "TopologyOptions": { "PublishedEventToTopicsMap": { "MyNamespace.SomeEvent": "some-event" }, "SubscribedEventToTopicsMap": { "MyNamespace.SomeEvent": [ "some-event", "some-other-event" ] }, "QueueNameToSubscriptionNameMap": { "Publisher": "PublisherSubscriptionName" } } } } ``` Using the migration topology ```json { "AzureServiceBus": { "MigrationTopologyOptions": { "TopicToPublishTo": "TopicToPublishTo", "TopicToSubscribeOn": "TopicToSubscribeOn", "EventsToMigrateMap": [ "MyNamespace.NotYetMigratedEvent" ], "SubscribedEventToRuleNameMap": { "MyNamespace.NotYetMigratedEvent": "EventRuleName" }, "PublishedEventToTopicsMap": { "MyNamespace.MigratedEvent": "MigratedEvent" }, "SubscribedEventToTopicsMap": { "MyNamespace.MigratedEvent": "MigratedEvent" }, "QueueNameToSubscriptionNameMap": { "Publisher": "PublisherSubscriptionName" } } } } ``` ## Assembly scanning [Assembly scanning](/nservicebus/hosting/assembly-scanning.md) loads assemblies from two locations: - The `bin` directory of the Azure Functions application - The Azure Functions runtime directory If the same assembly is present in both locations, an exception is thrown which prevents the endpoint from running. Contact [Particular Software support](https://particular.net/support) for assistance. ## Package requirements `NServiceBus.AzureFunctions.Worker.ServiceBus` requires Visual Studio 2019 and .NET SDK version `5.0.300` or higher. Older versions of the .NET SDK might display the following warning which prevents the trigger definition from being auto-generated: ```txt CSC : warning CS8032: An instance of analyzer NServiceBus.AzureFunctions.SourceGenerator.TriggerFunctionGenerator cannot be created from NServiceBus.AzureFunctions.SourceGenerator.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=3.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. The system cannot find the file specified.. ``` Starting in version 4.1.0 of `NServiceBus.AzureFunctions.Worker.ServiceBus` and `NServiceBus.AzureFunctions.InProcess.ServiceBus` , warning CS8032 is treated as an error. To suppress this error, update the project's .csproj file to include the following line in the `` section at the top: ```xml ``` This will revert CS8032 to a warning status so that it does not stop the build process.