Return the web session for the current request. Always guaranteed to
return an instance either matching to the session id requested by the
client, or with a new session id either because the client did not
specify one or because the underlying session had expired. Use of this
method does not automatically create a session. See WebSession
for more details.
Check whether the requested resource has been modified given the supplied
ETag (entity tag) and last-modified timestamp as determined by
the application. Also transparently prepares the response, setting HTTP
status, and adding "ETag" and "Last-Modified" headers when applicable.
This method works with conditional GET/HEAD requests as well as with
conditional POST/PUT/DELETE requests.
Return a log message prefix to use to correlate messages for this exchange.
The prefix is based on the value of the attribute ServerWebExchange.LOG_ID_ATTRIBUTE
along with some extra formatting so that the prefix can be conveniently
prepended with no further formatting no separators required.