6. Defining long-running resource operations

If your service uses any long-running operations (LROs; see our guidelines for specifics), you will need to define a "status monitor" operation which can report the status of the operation.

Let's say that we want to make our createOrUpdateWidget and deleteWidget operations long-running. Here's how we can update our Widgets interface to accomplish that:

import "@azure-tools/typespec-azure-core";

using Azure.Core;
using Azure.Core.Traits;

alias ServiceTraits = SupportsRepeatableRequests &
  SupportsConditionalRequests &
  SupportsClientRequestId;

alias Operations = Azure.Core.ResourceOperations<ServiceTraits>;

interface Widgets {
  @doc("Gets status of a Widget operation.")
  getWidgetOperationStatus is Operations.GetResourceOperationStatus<Widget>;

  @doc("Fetch a Widget by name.")
  getWidget is Operations.ResourceRead<Widget>;

  @doc("Creates or updates a Widget asynchronously.")
  @pollingOperation(Widgets.getWidgetOperationStatus)
  createOrUpdateWidget is Operations.LongRunningResourceCreateOrUpdate<Widget>;

  @doc("Delete a Widget asynchronously.")
  @pollingOperation(Widgets.getWidgetOperationStatus)
  deleteWidget is Operations.LongRunningResourceDelete<Widget>;

  @doc("List Widget resources.")
  listWidgets is Operations.ResourceList<Widget>;
}

1. We change createOrUpdateWidget to use LongRunningResourceCreateOrUpdate<Widget> and deleteWidget to use LongRunningResourceDelete.
2. We define the getWidgetOperationStatus operation based on the GetResourceOperationStatus signature. This defines the operation status monitor as a child resource of the Widget type so that it shows up under that resource in the route hierarchy.
3. We must add the pollingOperation decorator to both of the long-running operations and reference the Widgets.getWidgetOperationStatus operation. This connects the long-running operations to their associated status monitor operation to make it easier for service clients to be generated.

NOTE: The status monitor operation must be defined earlier in the interface than the long-running operations that reference it otherwise TypeSpec will not be able to resolve the reference!

See considerations for service design for more information about LROs.