Azure API Management Caching

Azure API Management (APIM) provides a caching feature that allows you to cache the responses of certain operations for a certain period of time. To use this feature, you would need to do the following:

1. Create an API Management instance on Azure if you haven't already.
2. Create an API or import an existing API into the API Management instance.
3. Go to the "Policies" section of the API and add a "cache" policy. You can specify the duration for which the responses should be cached and the key that should be used to cache the responses.
4. You can also use the "cache-lookup" and "cache-store" policies to control how the caching works.
5. Once you have added the caching policy, you can test your API to see if the caching is working as expected.

Here's an example of a cache policy that caches responses for 15 minutes:

<cache-control duration="900" vary-by-developer="false" vary-by-developer-groups="false" vary-by-headers="*" vary-by-query-parameters="*" />

The "cache-lookup" policy is used to check if a response for a particular request is already present in the cache. If a response is found in the cache, the policy returns that response and the request is not sent to the backend. If a response is not found in the cache, the policy allows the request to proceed to the backend, and the response is stored in the cache for future use.

The "cache-store" policy is used to store the response of a request in the cache. It is typically used in conjunction with the "cache-lookup" policy. When the "cache-lookup" policy determines that a response is not present in the cache, it allows the request to proceed to the backend. The backend then returns a response, which is then stored in the cache using the "cache-store" policy.

You can use these two policies together to control how the caching works for your API. For example, you can use the "cache-lookup" policy to check if a response is already present in the cache, and if it is not, use the "cache-store" policy to store the response in the cache for future use. Additionally, you can use the "cache-lookup" and "cache-store" policies in combination with other policies like "condition" or "set-variable" to create more complex caching scenarios.

Here is an example of how you can use the "cache-lookup" and "cache-store" policies together to cache responses for a certain period of time:

<cache-lookup vary-by-developer="false" vary-by-developer-groups="false" vary-by-headers="*" vary-by-query-parameters="*">
  <cache-store duration="900" />
</cache-lookup>

This example will check if a response for a request is already present in the cache and if not it will store the response in the cache for 15 minutes (900 seconds)

It's important to keep in mind that you should use caching judiciously and consider the trade-offs between performance and data freshness.