API Management: Advanced caching and throttling policies

A number of new policies are available now to extend the caching and throttling capabilities of API Management. * The [cache-lookup-value](https://msdn.microsoft.com/library/azure/dn894086.aspx#GetFromCacheByKey) and [cache-store-value](https://msdn.microsoft.com/library/azure/dn894086.aspx#StoreToCacheByKey) enable caching arbitrary pieces of data at arbitrary points during policy execution. * The [quota-by-key](https://msdn.microsoft.com/library/azure/dn894078.aspx#SetUsageQuotaByKey) and [rate-limit-by-key](https://msdn.microsoft.com/library/azure/dn894078.aspx#LimitCallRateByKey) policies allow partitioning quota and rate limits by using custom key values. This gives developers a finer degree of control over throttling to prevent denial-of-service attacks and to enable usage based tiers for end users. Advanced caching policies can support scenarios such as: * [Fragment caching ](https://azure.microsoft.com/documentation/articles/api-management-sample-cache-by-key/#fragment-caching) * [Transparent API versioning ](https://azure.microsoft.com/documentation/articles/api-management-sample-cache-by-key/#transparent-versioning) * [Tenant Isolation](https://azure.microsoft.com/documentation/articles/api-management-sample-cache-by-key/#tenant-isolation) Advanced throttling policies support scenarios such as: * [User Identity throttling](https://azure.microsoft.com/documentation/articles/api-management-sample-flexible-throttling/#user-identity-throttling) * [Client application driven throttling ](https://azure.microsoft.com/documentation/articles/api-management-sample-flexible-throttling/#client-driven-throttling) For more information, examples, and guidance on how to use these new policies, see: * [Advanced request throttling with Azure API Management](https://azure.microsoft.com/documentation/articles/api-management-sample-flexible-throttling/) * [Custom caching in Azure API Management](https://azure.microsoft.com/documentation/articles/api-management-sample-cache-by-key/) * API Management * Features * [ API Management](https://azure.microsoft.com/en-gb/products/api-management/)