How Integrated Caching Works
A brief overview of how Integrated Caching works on the System.
Summary
Integrated caching stores frequently requested content in the in-memory cache of the system. It intercepts all HTTP client requests and sends the response to the client if the response is stored in the integrated cache. Responses for requests may or may not be stored in the cache. When the requested content is found in the cache, the request is known as a cache hit. When the requested content is not found in the cache, the system sends the request to the origin server and the request is called a cache miss. There are two types of cache misses: storable and non-storable. A storable cache miss is one that can be stored in the cache when the origin serves the response, while a non-storable cache miss cannot be stored in the cache.
The following diagram illustrates the path that a transaction follows in the system in case of a cache hit, a storable cache miss, and a non-storable cache miss.
Transaction path
A typical static integrated cache configuration includes the following entities: content groups, policies, and cache objects.
The following diagram shows how the entities work in a static integrated cache configuration. 
Integrated cache entity model for static caching
As the figure shows, to configure integrated cache, you must configure policies and content groups. Policies consist of actions and expressions that enable the system to determine which requests and responses to cache. Content groups are entities that store the cached objects. Every cached object is a member of a content group. When the client requests content, the system evaluates the policies and if there is a cache hit, the system serves the client from the cache. However, if there is a cache miss, the content is fetched from the origin, cached in the integrated cache, and served to the client.
Requests for dynamic web applications are usually parameterized. In parameterized caching, the integrated cache must extract the following request parameters and their values:
- Parameters in the URL Query
- Parameters in the POST body
- Parameters in the Cookie header
The integrated cache can extract any combination of parameters of the request, and can therefore, cache dynamically generated content. Caching dynamic content requires parsing and evaluating parts of a request as well as a response. You must configure the following integrated cache entities for dynamic caching: content groups, cache policies, cache selectors, and cache objects.
The following diagram shows how the entities work in an integrated cache configuration for dynamic caching. 
Integrated cache entity model for dynamic caching
As the figure shows, to configure integrated cache for dynamic caching you must configure the following: content groups, cache selectors, and policies. Cache selectors are patterns or expressions that are formed of a combination of various parts of a request. The policies consist of actions and expressions that enable the system to determine which requests and responses to cache. Content groups are entities that store the cached objects. The content groups are associated with the cache selectors to store dynamic cached objects. Every cached object is a member of a content group. When the client requests dynamic content, the system uses selectors to filter through the cache to locate the appropriate response for the request.
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