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Swarm does not perform the requested method, and instead return a an HTTP 412 Precondition Failed response with a current ETag header if none of the entity tags match. This behavior is most useful when the client wants to prevent an updating method (such as PUT) from modifying an aliased object that changed since the client last retrieved it.
Swarm does not return a response status of HTTP 412 Precondition Failed unless it is consistent with all of the conditional header fields in the request if Swarm receives a conditional request that includes both a Last-Modified date (for example, in an If-Modified-Since or If-Unmodified-Since header field) and one or more entity tags as cache validators (for example, in an If-Match header field).
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Swarm does not perform the requested method if the entity tags match the primary object UUID that is returned in the response to a similar GET request (without the If-None-Match header) on that object or if "*" is given and the object does exist. Swarm responds with a an HTTP 304 Not Modified response, including a current ETag header for the object if the request method was GET or HEAD. Swarm responds with a response of HTTP 412 Precondition failed with the same current ETag as the GET or HEAD response for all other request methods. The object was modified if none of the previously recorded and supplied entity tags match. The requested method proceeds as if the If-None-Match header field did not exist.
Swarm does not return a response status of HTTP 304 Not Modified or HTTP 412 Precondition failed unless it is consistent with all of the conditional header fields in the request if Swarm receives a conditional request that includes both a Last-Modified date (for example, in an If-Modified-Since or If-Unmodified-Since header field) and one or more entity tags (for example, in an If-None-Match header field) as cache validators.
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If the entity tag given in the If-Range header matches the current primary object UUID or the HTTP-date given is not before the Last-Modified date of the object, Swarm provides the specified sub-range of the object using a an HTTP 206 Partial content response. If the entity tag does not match, Swarm returns the entire object using a an HTTP 200 OK response.
HTTP 1.0 Caching Headers
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Swarm performs the requested method as if the If-Unmodified-Since header is not present if the requested object is not modified since the time specified in this field.
Swarm does not perform the requested method, and instead, returns a an HTTP 412 Precondition failed if the requested object is modified since the specified time.
The header is ignored if the specified date is invalid.
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