# Overview - Google App Engine - Google Code

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# Overview

With the Capabilities API, your application can detect outages and scheduled downtime for specific API capabilities. You can use this API to reduce downtime in your application by detecting when a capability is unavailable and then bypassing it.

## Using the Capabilities API in Java

Each Capability is represented as a static constant on the Capability class (such as Capability.DATASTORE_WRITE). Each Capability has a state, which you can retrieve from CapabilitiesService.getStatus(Capability). Each state has a status, which is an enumeration reflecting a the availability of a capability: either `ENABLED` or `DISABLED`. See below for the list of services currently enabled in this API.

## Supported Capabilities

The API currently supports the following capabilities:

Capability | Argument to `Capability`
--- | ---
Availability of the blobstore | BLOBSTORE
Datastore reads | DATASTORE
Datastore writes | DATASTORE_WRITES
Availability of the Images service | IMAGES
Availability of the Mail service | MAIL
Availability of the Memcache service | MEMCACHE
Availability of the Task Queue service | TASKQUEUE
Availability of the URL Fetch service | URL_FETCH
Availability of the XMPP service | XMPP