您的應用程式可使用 Capabilities API 來偵測特定 API 功能的運作中斷和排定停機時間。您可以使用這個 API 來偵測特定功能無法使用的時間，然後略過該功能，藉此縮短應用程式中的停機時間。。
舉例來說，如果您使用 Images API 調整圖片大小，您可以利用 Capabilities API 來偵測 Images API 無法使用的時間，並略過調整大小：
fromgoogle.appengine.apiimportcapabilitiesdefStoreUploadedProfileImage(self):uploaded_image=self.request.get('img')# If the images API is unavailable, we'll just skip the resize.ifcapabilities.CapabilitySet('images').is_enabled():uploaded_image=images.resize(uploaded_image,64,64)store(uploaded_image)
Datastore API 提供了方便資料儲存庫讀取和寫入功能的包裝函式。雖然只需將功能名稱以引數的形式提供給 CapabilitySet()，即可測試功能。但在這種情況下，您也可使用 db.READ_CAPABILITY 和 db.WRITE_CAPABILITY 便利 CapabilitySet 物件。以下範例顯示如何使用便利包裝函式，偵測資料儲存庫的寫入可用性，以及如何在停機期間向使用者提供相關訊息：
fromgoogle.appengine.extimportdbdefRenderHTMLForm(self):ifnotdb.WRITE_CAPABILITY.is_enabled():# Datastore is in read-only mode.
在 Python 2 中使用 Capabilities API
CapabilitySet 類別定義了此 API 所有的可用方法，您可以明確地指出功能，或是透過此類別提供的方法去推測這些功能。請參閱下方內容，取得這個 API 目前已啟用的服務清單。
[[["容易理解","easyToUnderstand","thumb-up"],["確實解決了我的問題","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["難以理解","hardToUnderstand","thumb-down"],["資訊或程式碼範例有誤","incorrectInformationOrSampleCode","thumb-down"],["缺少我需要的資訊/範例","missingTheInformationSamplesINeed","thumb-down"],["翻譯問題","translationIssue","thumb-down"],["其他","otherDown","thumb-down"]],["上次更新時間：2025-09-04 (世界標準時間)。"],[[["\u003cp\u003eThe Capabilities API allows applications to detect outages and scheduled downtime for specific API capabilities, helping to reduce application downtime by bypassing unavailable features.\u003c/p\u003e\n"],["\u003cp\u003eThis API supports first-generation runtimes and can be utilized when upgrading to corresponding second-generation runtimes, with specific migration guidance for the App Engine Python 3 runtime.\u003c/p\u003e\n"],["\u003cp\u003eWhile \u003ccode\u003eis_enabled\u003c/code\u003e generally returns \u003ccode\u003etrue\u003c/code\u003e, the "Datastore writes" capability returns \u003ccode\u003efalse\u003c/code\u003e if Datastore is in read-only mode.\u003c/p\u003e\n"],["\u003cp\u003eThe API can be used by explicitly naming capabilities or by inferring them from the \u003ccode\u003eCapabilitySet\u003c/code\u003e class methods.\u003c/p\u003e\n"],["\u003cp\u003eThe API currently supports capabilities like blobstore, Datastore reads and writes, Images, Mail, Memcache, Task Queue, and URL Fetch services.\u003c/p\u003e\n"]]],[],null,["# Capabilities API for legacy bundled services\n\nWith the Capabilities API, your application can detect outages and scheduled\ndowntime for specific [API capabilities](#Supported_capabilities). You can use\nthis API to reduce downtime in your application by detecting when a capability\nis unavailable and then bypassing it. .\n| This API is supported for first-generation runtimes and can be used when [upgrading to corresponding second-generation runtimes](/appengine/docs/standard/\n| python3\n|\n| /services/access). If you are updating to the App Engine Python 3 runtime, refer to the [migration guide](/appengine/migration-center/standard/migrate-to-second-gen/python-differences) to learn about your migration options for legacy bundled services.\n| Every `is_enabled` request to this API always returns\n| `true` except for the \"Datastore writes\" capability, which\n| returns `false` if Datastore is in read-only\n| mode for your app.\n\nFor example, if you use the Images API to resize images, you can use the\nCapabilities API to detect when the Images API is unavailable and skip the\nresize: \n\n from google.appengine.api import capabilities\n\n def StoreUploadedProfileImage(self):\n uploaded_image = self.request.get('img')\n # If the images API is unavailable, we'll just skip the resize.\n if capabilities.CapabilitySet('images').is_enabled():\n uploaded_image = images.resize(uploaded_image, 64, 64)\n store(uploaded_image)\n\nThe Datastore API provides a convenience wrapper for the Datastore read and\nwrite capabilities. While you can test capabilities simply by supplying the\ncapability name as an argument to `CapabilitySet()`, in this case you can also\nuse the `db.READ_CAPABILITY` and `db.WRITE_CAPABILITY` convenience\n`CapabilitySet` objects. The following sample shows how to detect the\navailability of Datastore writes using a convenience wrapper and, during\ndowntime, provide a message to users: \n\n from google.appengine.ext import db\n\n def RenderHTMLForm(self):\n if not db.WRITE_CAPABILITY.is_enabled():\n # Datastore is in read-only mode.\n\nUsing the Capabilities API in Python 2\n--------------------------------------\n\nThe\n[CapabilitySet](/appengine/docs/legacy/standard/python/refdocs/google.appengine.api.capabilities#google.appengine.api.capabilities.CapabilitySet)\nclass defines all of the\navailable methods for this API. You can either name capabilities explicitly or\ninfer them from the methods provided by this class. See below for the\n[list of services](#Supported_capabilities) currently enabled in this API.\n\nSupported capabilities\n----------------------\n\nThe API currently supports the following capabilities:"]]
