Google have announced the release of version 1.4.0 of the popular App Engine SDK. The major feature additions in this release are the Channel API, Always On and Warm Up Requests:
- Always On - For high-priority applications with low or variable traffic, you can now reserve instances via App Engine's Always On feature. Always On is a premium feature costing $9 per month which reserves three instances of your application, never turning them off, even if the application has no traffic. This mitigates the impact of loading requests on applications that have small or variable amounts of traffic.
- Warm Up Requests - This feature reduces time to serve requests by anticipating the need for more instances and loading them before user traffic is sent to the new instance. It can be enabled for all applications through app.yaml or appengine-web.xml and is enabled by default for applications that have purchased Always On. Once enabled, warm up requests will be sent whenever possible to load new instances of your application before it begins serving user traffic.
On top of these features, Google have works on some of the limitations of existing APIs by changing the limit for background work from 30 seconds to 10 minutes, and by increasing call size limits with response, memsize and image API limits all raised to 32MB, and outgoing Mail API attachments increased to 10MB.