You can migrate from using App Engine standard environment's queue service (Task Queues) via the App Engine Task Queue API to accessing that same service using Cloud Tasks, a new RPC/REST API. Cloud Tasks can be employed outside of first generation App Engine runtimes, particularly from all App Engine flexible environments, as well as from second generation App Engine standard environment runtimes.
Cloud Tasks and the current App Engine standard environment task queue service exist in a single universe. You can add to the same queues through either API. In both cases, a queue is owned by an app. Regardless of whether you use the App Engine SDK or the new Cloud Tasks API , a queue within the app forwards a task to a handler URL for asynchronous processing.
Cloud Tasks provides some features not available via the App Engine SDK, including the following:
Queue management via the API:
You can create, delete, pause, and perform other queue management tasks using the API, through the Console, or via the
List Queues command:
You can list all the queues you have set up in your project.
List Tasks command:
You can list all the tasks in any of your queues.
Identity and Access Management (IAM) integration:
You can secure access to your queues and tasks in a highly granular way using IAM.
Features in Task Queues not yet available via Cloud Tasks API :
You can use Cloud Pub/Sub, a GA product, to implement many of the same use cases as pull queues.
Cloud Tasks does not support enqueuing a task as part of a Cloud Datastore transaction, such that the task is only enqueued - and is guaranteed to be enqueued - if the transaction is committed successfully.
In some cases where you might need a series of diverse small tasks handled asynchronously but you don't want to go through the work of setting up individual distinct handlers, the App Engine SDK allows you to use runtime specific libraries to create simple functions to manage these tasks. This feature is not available in Cloud Tasks. Note, though, that normal tasks can be scheduled in the future using Cloud Tasks.
Some of the runtimes that use the App Engine SDK have APIs that support task multitenancy through namespacing. This feature is not available in Cloud Tasks.
The local development server provided by the Cloud SDK or the App Engine SDK does not support simulated endpoints for Cloud Tasks API calls.
Users of the App Engine SDK can choose to add tasks to queues asynchronously. This feature is not available in Cloud Tasks.
For more information
More detailed guides for migrating your code can be found in the App Engine Task Queue documentation set: