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Swarm returns the Last-Modified header for all POST, PUT, COPY, APPEND, GET, and HEAD operations. For both ordinary objects and aliased objects, the The value of the header is exactly the same as the Castor-System-Created header for both ordinary objects and aliased objects.
For ordinary objects, this This is the original object time stamp for ordinary objects.
For aliased objects, this This is the server time when the alias was last updated for aliased objects.
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Castor-System-Created deprecatedThe Castor-System-Created header is deprecated, replaced with the more standard Last-Modified header. For backward compatibility with previously stored data, Swarm continues to generate both headers and behave as it does now if it encounters an object with a Castor-System-Created header, but without a Last-Modified header. If a stored object includes both headers, Swarm uses the value of the Last-Modified header. A future release ceases generating the deprecated header for newly-stored content. |
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NoteIf-Modified-Since is for use with GET and HEAD requests (not writes). If specifying a date in the future, Swarm ignores it. |
If An entity is not returned from the server if the requested object was not modified since the time specified in the If-Modified-Since header, an entity is not returned from the server. Instead, a 304 Not Modified response is returned without any message-body.
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The Expires header field provides the final date and time when the response is considered stale. A stale cache entry may not normally be returned by a cache (either a proxy cache or a user agent cache) unless it is first validated with Swarm (or with an intermediate cache that has a fresh copy of the object). Since Swarm has no information about when an aliased object may be updated and little information about when an object may be deleted, Swarm does not generate an Expires header for any object. However, Expires are added to the list of persisted headers so applications can supply a hint to caching proxies and clients as to when an object may become stale.