[[["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：2025-08-18 (世界標準時間)。"],[[["\u003cp\u003eReusing a single Apigee Quota policy across multiple flows or target endpoints causes the quota counter to decrement each time it's executed, leading to unexpected quota violations.\u003c/p\u003e\n"],["\u003cp\u003eWhen a Quota policy is reused in different target endpoints, a single counter tracks requests collectively, instead of separately for each endpoint, potentially exhausting the quota limit prematurely.\u003c/p\u003e\n"],["\u003cp\u003eTo maintain individual quota counters when reusing a Quota policy, use the \u003ccode\u003e<Identifier>\u003c/code\u003e element, such as referencing a header value, to differentiate between the contexts in which the policy is executed.\u003c/p\u003e\n"],["\u003cp\u003eAn alternative to reusing a Quota policy is to define separate Quota policies for each flow or target endpoint, ensuring that each endpoint has its own dedicated counter to accurately track and enforce the specified quota.\u003c/p\u003e\n"]]],[],null,["# Antipattern: Re-use a Quota policy\n\n*You're viewing **Apigee** and **Apigee hybrid** documentation.\nView [Apigee Edge](https://docs.apigee.com/api-platform/antipatterns/reusing-quota) documentation.*\n\nApigee provides the ability to configure the number of allowed requests for an API Proxy for\na specific period of time using the [Quota policy](/apigee/docs/api-platform/reference/policies/quota-policy).\n\nAntipattern\n-----------\n\nIf a [Quota policy](/apigee/docs/api-platform/reference/policies/quota-policy) is reused, then the quota counter will be decremented each time the\nQuota policy gets executed irrespective of where it is used. That is, if a Quota policy is\nreused:\n\n- Within the same flow or different flows of an API proxy\n- In different target endpoints of an API proxy\n\nThen the quota counter gets decremented each time it is executed and we will end up getting\nQuota violation errors much earlier than the expected for the specified interval of time.\n\nLet's use the following example to explain how this works.\n\n### API Proxy\n\nLet's say we have an API proxy named \"TestTargetServerQuota\", which routes traffic to two\ndifferent target servers based on the resource path. And we would like to restrict the API traffic\nto 10 requests per minute for each of these target servers. Here's the table that depicts this\nscenario:\n\n### Quota policy\n\nSince the traffic quota is same for both the target servers, we define single Quota policy\nnamed \"Quota-Minute-Target-Server\" as shown below: \n\n```world-of-warcraft-toc\n\u003c!-- /antipatterns/examples/1-8.xml --\u003e\n\u003cQuota name=\"Quota-Minute-Target-Server\"\u003e\n \u003cInterval\u003e1\u003c/Interval\u003e\n \u003cTimeUnit\u003eminute\u003c/TimeUnit\u003e\n \u003cDistributed\u003etrue\u003c/Distributed\u003e\n \u003cAllow count=\"10\"/\u003e\n\u003c/Quota\u003e\n```\n\n### Target endpoints\n\nLet's use the Quota policy \"Quota-Minute-Target-Server\" in the preflow of the target endpoint\n\"Target-US\": \n\n```world-of-warcraft-toc\n\u003c!-- /antipatterns/examples/1-9.xml --\u003e\n\u003cTargetEndpoint name=\"Target-US\"\u003e\n \u003cPreFlow name=\"PreFlow\"\u003e\n \u003cRequest\u003e\n \u003cStep\u003e\n \u003cName\u003eQuota-Minute-Target-Server\u003c/Name\u003e\n \u003c/Step\u003e\n \u003c/Request\u003e\n \u003c/PreFlow\u003e\n \u003cHTTPTargetConnection\u003e\n \u003cURL\u003ehttp://target-us.somedomain.com\u003c/URL\u003e\n \u003c/HTTPTargetConnection\u003e\n\u003c/TargetEndpoint\u003e\n```\n\nAnd reuse the same Quota policy \"Quota-Minute-Target-Server\" in the preflow of the other target\nendpoint \"Target-EU\" as well: \n\n```world-of-warcraft-toc\n\u003c!-- /antipatterns/examples/1-10.xml --\u003e\n\u003cTargetEndpoint name=\"Target-EU\"\u003e\n \u003cPreFlow name=\"PreFlow\"\u003e\n \u003cRequest\u003e\n \u003cStep\u003e\n \u003cName\u003eQuota-Minute-Target-Server\u003c/Name\u003e\n \u003c/Step\u003e\n \u003c/Request\u003e\n \u003cResponse/\u003e\n \u003c/PreFlow\u003e\n \u003cHTTPTargetConnection\u003e\n \u003cURL\u003ehttp://target-us.somedomain.com\u003c/URL\u003e\n \u003c/HTTPTargetConnection\u003e\n\u003c/TargetEndpoint\u003e\n```\n\n### Incoming traffic pattern\n\nLet's say we get a total of 10 API requests for this API proxy within the first 30 seconds in\nthe following pattern:\n\nA little later, we get the 11th API request with the resource path as `/target-us`,\nlet's say after 32 seconds.\n\nWe expect the request to go through successfully assuming that we still have 6 API requests for\nthe target endpoint `target-us` as per the quota allowed.\n\nHowever, in reality, we get a `Quota violation error`.\n\n**Reason:** Since we are using the same Quota policy in both the target endpoints, a\nsingle quota counter is used to track the API requests hitting both the target endpoints. Thus we\nexhaust the quota of 10 requests per minute collectively rather than for the individual target\nendpoint.\n\nImpact\n------\n\nThis antipattern can result in a fundamental mismatch of expectations, leading to a perception\nthat the quota limits got exhausted ahead of time.\n\nBest practice\n-------------\n\n- Use the `\u003cClass\u003e` or `\u003cIdentifier\u003e` elements to ensure multiple, unique counters are maintained by defining a single [Quota policy](/apigee/docs/api-platform/reference/policies/quota-policy). Let's redefine the Quota policy \"Quota-Minute-Target-Server\" that we just explained in the previous section by using the header `target_id` as the `\u003cIdentifier\u003e` for as shown below: \n\n ```world-of-warcraft-toc\n \u003c!-- /antipatterns/examples/1-11.xml --\u003e\n \u003cQuota name=\"Quota-Minute-Target-Server\"\u003e\n \u003cInterval\u003e1\u003c/Interval\u003e\n \u003cTimeUnit\u003eminute\u003c/TimeUnit\u003e\n \u003cAllow count=\"10\"/\u003e\n \u003cIdentifier ref=\"request.header.target_id\"/\u003e\n \u003cDistributed\u003etrue\u003c/Distributed\u003e\n \u003c/Quota\u003e\n ```\n - We will continue to use this Quota policy in both the target endpoints \"Target-US\" and \"Target-EU\" as before.\n - Now let's say if the header `target_id` has a value \"US\" then the requests are routed to the target endpoint \"Target-US\".\n - Similarly if the header `target_id` has a value \"EU\" then the requests are routed to the target endpoint \"Target-EU\".\n - So even if we use the same Quota policy in both the target endpoints, separate quota counters are maintained based on the `\u003cIdentifier\u003e` value.\n - Therefore, by using the `\u003cIdentifier\u003e` element we can ensure that each of the target endpoints get the allowed quota of 10 requests.\n- Use separate Quota policy in each of the flows/target endpoints/API Proxies to ensure that you always get the allowed count of API requests. Let's now look at the same example used in the above section to see how we can achieve the allowed quota of 10 requests for each of the target endpoints.\n - Define a separate Quota policy, one each for the target endpoints \"Target-US\" and \"Target-EU\" Quota policy for Target Endpoint \"Target-US\":\n\n ```world-of-warcraft-toc\n \u003c!-- /antipatterns/examples/1-12.xml --\u003e\n \u003cQuota name=\"Quota-Minute-Target-Server-US\"\u003e\n \u003cInterval\u003e1\u003c/Interval\u003e\n \u003cTimeUnit\u003eminute\u003c/TimeUnit\u003e\n \u003cDistributed\u003etrue\u003c/Distributed\u003e\n \u003cAllow count=\"10\"/\u003e\n \u003c/Quota\u003e\n ```\n\n Quota policy for Target Endpoint \"Target-EU\": \n\n ```world-of-warcraft-toc\n \u003c!-- /antipatterns/examples/1-13.xml --\u003e\n \u003cQuota name=\"Quota-Minute-Target-Server-EU\"\u003e\n \u003cInterval\u003e1\u003c/Interval\u003e\n \u003cTimeUnit\u003eminute\u003c/TimeUnit\u003e\n \u003cDistributed\u003etrue\u003c/Distributed\u003e\n \u003cAllow count=\"10\"/\u003e\n \u003c/Quota\u003e\n ```\n - Use the respective quota policy in the definition of the target endpoints as shown below: Target Endpoint \"Target-US\":\n\n ```world-of-warcraft-toc\n \u003c!-- /antipatterns/examples/1-14.xml --\u003e\n \u003cTargetEndpoint name=\"Target-US\"\u003e\n \u003cPreFlow name=\"PreFlow\"\u003e\n \u003cRequest\u003e\n \u003cStep\u003e\n \u003cName\u003eQuota-Minute-Target-Server-US\u003c/Name\u003e\n \u003c/Step\u003e\n \u003c/Request\u003e\n \u003cResponse/\u003e\n \u003c/PreFlow\u003e\n \u003cHTTPTargetConnection\u003e\n \u003cURL\u003ehttp://target-us.somedomain.com\u003c/URL\u003e\n \u003c/HTTPTargetConnection\u003e\n \u003c/TargetEndpoint\u003e\n ```\n\n Target Endpoint \"Target-EU\": \n\n ```world-of-warcraft-toc\n \u003c!-- /antipatterns/examples/1-15.xml --\u003e\n \u003cTargetEndpoint name=\"Target-EU\"\u003e\n \u003cPreFlow name=\"PreFlow\"\u003e\n \u003cRequest\u003e\n \u003cStep\u003e\n \u003cName\u003eQuota-Minute-Target-Server-EU\u003c/Name\u003e\n \u003c/Step\u003e\n \u003c/Request\u003e\n \u003cResponse/\u003e\n \u003c/PreFlow\u003e\n \u003cHTTPTargetConnection\u003e\n \u003cURL\u003ehttp://target-eu.somedomain.com\u003c/URL\u003e\n \u003c/HTTPTargetConnection\u003e\n \u003c/TargetEndpoint\u003e\n ```\n - Since we are using separate Quota policy in the target endpoints \"Target-US\" and \"Target-EU\", a separate counter will be maintained. This ensures that we get the allowed quota of 10 API requests per minute for each of the target endpoints.\n- Use the `\u003cClass\u003e` or `\u003cIdentifier\u003e` elements to ensure multiple, unique counters are maintained."]]
