- From: Julian Reschke <julian.reschke@gmx.de>
- Date: Fri, 15 Jun 2007 14:29:50 +0200
- To: HTTP Working Group <ietf-http-wg@w3.org>
See <http://www.w3.org/Protocols/HTTP/1.1/rfc2616bis/issues/#i52>.
There was an open action item for me to sort the terminology section,
and to post the outcome over here for discussion (I'll add my opinion in
a separate mail).
After sorting by terms, Section 1.3 would look like this:
-- snip --
1.3. Terminology
This specification uses a number of terms to refer to the roles
played by participants in, and objects of, the HTTP communication.
age
The age of a response is the time since it was sent by, or
successfully validated with, the origin server.
cache
A program's local store of response messages and the subsystem
that controls its message storage, retrieval, and deletion. A
cache stores cacheable responses in order to reduce the response
time and network bandwidth consumption on future, equivalent
requests. Any client or server may include a cache, though a
cache cannot be used by a server that is acting as a tunnel.
cacheable
A response is cacheable if a cache is allowed to store a copy of
the response message for use in answering subsequent requests.
The rules for determining the cacheability of HTTP responses are
defined in Section 13. Even if a resource is cacheable, there may
be additional constraints on whether a cache can use the cached
copy for a particular request.
client
A program that establishes connections for the purpose of sending
requests.
connection
A transport layer virtual circuit established between two programs
for the purpose of communication.
content negotiation
The mechanism for selecting the appropriate representation when
servicing a request, as described in Section 12. The
representation of entities in any response can be negotiated
(including error responses).
entity
The information transferred as the payload of a request or
response. An entity consists of metainformation in the form of
entity-header fields and content in the form of an entity-body, as
described in Section 7.
explicit expiration time
The time at which the origin server intends that an entity should
no longer be returned by a cache without further validation.
first-hand
A response is first-hand if it comes directly and without
unnecessary delay from the origin server, perhaps via one or more
proxies. A response is also first-hand if its validity has just
been checked directly with the origin server.
fresh
A response is fresh if its age has not yet exceeded its freshness
lifetime.
freshness lifetime
The length of time between the generation of a response and its
expiration time.
gateway
A server which acts as an intermediary for some other server.
Unlike a proxy, a gateway receives requests as if it were the
origin server for the requested resource; the requesting client
may not be aware that it is communicating with a gateway.
heuristic expiration time
An expiration time assigned by a cache when no explicit expiration
time is available.
inbound/outbound
Inbound and outbound refer to the request and response paths for
messages: "inbound" means "traveling toward the origin server",
and "outbound" means "traveling toward the user agent"
message
The basic unit of HTTP communication, consisting of a structured
sequence of octets matching the syntax defined in Section 4 and
transmitted via the connection.
origin server
The server on which a given resource resides or is to be created.
proxy
An intermediary program which acts as both a server and a client
for the purpose of making requests on behalf of other clients.
Requests are serviced internally or by passing them on, with
possible translation, to other servers. A proxy MUST implement
both the client and server requirements of this specification. A
"transparent proxy" is a proxy that does not modify the request or
response beyond what is required for proxy authentication and
identification. A "non-transparent proxy" is a proxy that
modifies the request or response in order to provide some added
service to the user agent, such as group annotation services,
media type transformation, protocol reduction, or anonymity
filtering. Except where either transparent or non-transparent
behavior is explicitly stated, the HTTP proxy requirements apply
to both types of proxies.
representation
An entity included with a response that is subject to content
negotiation, as described in Section 12. There may exist multiple
representations associated with a particular response status.
request
An HTTP request message, as defined in Section 5.
resource
A network data object or service that can be identified by a URI,
as defined in Section 3.2. Resources may be available in multiple
representations (e.g. multiple languages, data formats, size, and
resolutions) or vary in other ways.
response
An HTTP response message, as defined in Section 6.
semantically transparent
A cache behaves in a "semantically transparent" manner, with
respect to a particular response, when its use affects neither the
requesting client nor the origin server, except to improve
performance. When a cache is semantically transparent, the client
receives exactly the same response (except for hop-by-hop headers)
that it would have received had its request been handled directly
by the origin server.
server
An application program that accepts connections in order to
service requests by sending back responses. Any given program may
be capable of being both a client and a server; our use of these
terms refers only to the role being performed by the program for a
particular connection, rather than to the program's capabilities
in general. Likewise, any server may act as an origin server,
proxy, gateway, or tunnel, switching behavior based on the nature
of each request.
stale
A response is stale if its age has passed its freshness lifetime.
tunnel
An intermediary program which is acting as a blind relay between
two connections. Once active, a tunnel is not considered a party
to the HTTP communication, though the tunnel may have been
initiated by an HTTP request. The tunnel ceases to exist when
both ends of the relayed connections are closed.
upstream/downstream
Upstream and downstream describe the flow of a message: all
messages flow from upstream to downstream.
user agent
The client which initiates a request. These are often browsers,
editors, spiders (web-traversing robots), or other end user tools.
validator
A protocol element (e.g., an entity tag or a Last-Modified time)
that is used to find out whether a cache entry is an equivalent
copy of an entity.
variant
A resource may have one, or more than one, representation(s)
associated with it at any given instant. Each of these
representations is termed a `variant'. Use of the term `variant'
does not necessarily imply that the resource is subject to content
negotiation.
-- snip --
Best regards, Julian
Received on Friday, 15 June 2007 12:30:15 UTC