id id

Image/Metadata Version. When working with content that changes frequently, servers in caching networks such as Akamai, browser caches, and corporate proxy server caches may store Image Serving responses which may be out of date for periods of time.

id= *val*

Image Serving includes a versioning mechanism which can help reduce the chance that an outdated cache entry is used by an application. This mechanism involves using req=props to obtain version identifier strings for image data and metadata (such as image map or zoom target data). The version identifier string is then added to cacheable Image Serving requests with the id= command.

When a source image or metadata changes, the corresponding version id value also changes. Including an up-to-date version id value with the id= command ensures that old cache entries can no longer be accessed.

The following table lists the version identifier strings to be used for each req= type:

req= types not listed above either have a short TTL ( attribute::NonImgExpiration) or their responses are not cacheable at all; there is no advantage to including id= with such requests.

Properties section-62e973d0d5884abebbb0679f9278ae2c

Request attribute. Optional. Always ignored by the server.

Default section-96136720c82842c89505347ec39e6024

None.

Example section-a5fb871e0ec8485c91c4fca78895d17f

See the description of rect= for example usage.

See Also section-6b4befb47202415195a68516f60e9988

req= , rect=, catalog::Expiration, attribute::NonImgExpiration