DefaultCacheCapabilities Enumeration

0x00000000

None

A cache implementation does not provide any of the features that are described in DefaultCacheCapabilities

0x00000001

InMemoryProvider

Cache implementation runs at least partially in memory

0x00000002

OutOfProcessProvider

Cache implementation runs out-of-process

0x00000004

CacheEntryChangeMonitors

Cache implementation supports the ability to create change monitors that monitor entries

0x00000008

AbsoluteExpirations

Cache implementation supports the ability to automatically remove cache entries at a specific date and time

0x00000010

SlidingExpirations

Cache implementation supports the ability to automatically remove cache entries that have not been accessed in a specified time span

0x00000020

CacheEntryUpdateCallback

Cache implementation can raise a notification that an entry is about to be removed from the cache

0x00000040

CacheEntryRemovedCallback

Cache implementation can raise a notification that an entry has been removed from the cache

0x00000080

CacheRegions

Cache implementation supports the ability to partition its storage into cache regions.

When CacheRegion is not supported, then the cache consumer should never call DeleteRegion. Instead, DeleteAll should be used when a group of items are to be deleted all at once.

Cache consumers such as the Documents toolkit will always call add or get items with a key and a region name. If your custom cache does not support regions (or grouping), then use the regionName + keyName as the unique identifier for the cache item. ExternalResources is supported by FileCache since it has direct access to the cache items stored in disk and can delete the whole directory (region) when DeleteRegion is called in one shot.

0x00000100

ExternalResources

Cache implementation supports obtaining a URI to cache items providing direct file read or write access.

If the cache supports external resources then consumers may call BeginAddExternalResource to obtain file read or write access to the cache item through a URI to enhance performance when adding an item with large amount of binary data such as image files and EndAddExternalResource<T> to commit or discard the changes. Similarly, GetItemExternalResource and RemoveItemExternalResource may be called by the consumer to get such access on existing items or when they are removed from the cache. ExternalResources is supported by FileCache since it has direct access to the cache items stored in disk.

0x00000200

Serialization

Cache implementation supports serialization

This is a hint to the cache users that this implementation will serialize the objects added to the cache right away. This means that the original object is not shared and cannot be modified by the cache after adding it since a copy is generated through the platform serialization.

If the cache does not support or may perform serialization at a later time (when local memory is exhausted for instance), the cache user should always store a clone of the object into the cache.

0x00000400

VirtualDirectory

Cache implementation supports obtaining a URI to cache items providing HTTP GET access.

If the cache supports obtaining GET access to cache items then consumers may call GetItemVirtualDirectoryUrl to obtain the URL to the cache item to speed up access to the item data from a web service. ExternalResources is supported by FileCache.