api-management-howto-cache.md

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Add caching to improve performance in Azure API Management | Microsoft Docs	Learn how to improve the latency, bandwidth consumption, and web service load for API Management service calls.	api-management		vladvino	erikre		740f6a27-8323-474d-ade2-828ae0c75e7a	api-management	mobile	na	na	get-started-article	11/27/2018	apimpm

Add caching to improve performance in Azure API Management

Operations in API Management can be configured for response caching. Response caching can significantly reduce API latency, bandwidth consumption, and web service load for data that does not change frequently.

For more detailed information about caching, see API Management caching policies and Custom caching in Azure API Management.

What you'll learn:

[!div class="checklist"]

• Add response caching for your API
• Verify caching in action

Availability

Note

Internal cache is not available in the Consumption tier of Azure API Management. You can use an external Azure Cache for Redis instead.

Prerequisites

To complete this tutorial:

• Create an Azure API Management instance
• Import and publish an API

Add the caching policies

With caching policies shown in this example, the first request to the GetSpeakers operation returns a response from the backend service. This response is cached, keyed by the specified headers and query string parameters. Subsequent calls to the operation, with matching parameters, will have the cached response returned, until the cache duration interval has expired.

1. Sign in to the Azure portal at https://portal.azure.com.

2. Browse to your APIM instance.

3. Select the API tab.

4. Click Demo Conference API from your API list.

5. Select GetSpeakers.

6. On the top of the screen, select Design tab.

7. In the Inbound processing section, click the </> icon.

   

8. In the inbound element, add the following policy:

    <cache-lookup vary-by-developer="false" vary-by-developer-groups="false">
        <vary-by-header>Accept</vary-by-header>
        <vary-by-header>Accept-Charset</vary-by-header>
        <vary-by-header>Authorization</vary-by-header>
    </cache-lookup>
   

9. In the outbound element, add the following policy:

    <cache-store caching-mode="cache-on" duration="20" />
   

   Duration specifies the expiration interval of the cached responses. In this example, the interval is 20 seconds.

Tip

If you are using an external cache, as described in Use an external Azure Cache for Redis in Azure API Management, you may want to specify the cache-preference attribute of the caching policies. See API Management caching policies for more details.

Call an operation and test the caching

To see the caching in action, call the operation from the developer portal.

1. In the Azure portal, browse to your APIM instance.
2. Select the APIs tab.
3. Select the API to which you added caching policies.
4. Select the GetSpeakers operation.
5. Click the Test tab in the top right menu.
6. Press Send.

Next steps

• For more information about caching policies, see Caching policies in the API Management policy reference.
• For information on caching items by key using policy expressions, see Custom caching in Azure API Management.
• For more information about using external Azure Cache for Redis, see Use an external Azure Cache for Redis in Azure API Management.