Multi-version data caching

A method of serving data from a cache, comprising:

• receiving at the cache a request for a data item;
• extracting from said request a first parameter identifying said data item;
• conducting a first search of the cache for said data item with said first parameter;
• if said first search locates said data item in the cache, serving said data item;
• and
• if said first search identifies a policy for serving said data item:
• extracting from said request a value for a second parameter specified by said policy;
• and
• conducting a second search of the cache with said second parameter value.

A computer readable storage medium storing instructions that, when executed by a computer, cause the computer to perform a method of serving one of multiple versions of a data item from a cache, the method comprising:

• receiving at the cache a data request, wherein the requested data is identified by a data identifier;
• searching the cache with said data identifier;
• receiving, in response to said search, a policy for serving said requested data, wherein said policy identifies a parameter of said request other than said data identifier;
• applying said policy to locate in the cache a first version of said requested data corresponding to a value of said parameter included in said data request;
• and
• serving said first version of said requested data in response to said data request.

A computer readable storage medium storing instructions that, when executed by a computer, cause the computer to perform a method of serving data from a cache, the method comprising:

• receiving at the cache a request for a data item;
• extracting from said request a first parameter identifying said data item;
• conducting a first search of the cache for said data item with said first parameter;
• if said first search locates said data item in the cache, serving said data item;
• and
• if said first search identifies a policy for serving said data item:
• extracting from said request a value for a second parameter specified by said policy;
• and
• conducting a second search of the cache with said second parameter value.

A cache system, comprising:

• storage means configured to cache multiple versions of a first set of data, wherein said first set of data is identifiable by a data identifier;
• policy means configured to specify a policy for serving one of said multiple versions of said first set of data in response to a data request;
• and
• parsing means configured to parse said data request to retrieve a value for a parameter identified in said policy, wherein said parameter is a parameter other than said data identifier;
• wherein said version of said first set of data to be served in response to said data request is determined by said value.