On Feb 19, 2008, at 7:55 AM, Kris Zyp wrote:
Extra Connection Support
The XMLHttpRequest should define a property called
"extraConnection". When
extraConnection is set to true, it indicates that this XHR object's
connection SHOULD NOT be counted against the user agent's connection
limit.
That is if the user agent adheres to the two-connection limit as
recommended
by RFC 2616 section 8.1.4, it SHOULD allow two connections not
counting this
XHR object's connection. If the user agent has other or additional
connection
limits, this connection should not be counted in the accounting for
these
connection limits.
As with pipelining, I think this would be better handled at the HTTP
level than the XHR API level. We could define response headers for a
server to indicate that it allows more than two connections per
client, or alternately that a specific connection should not count
towards the limit.
- Maciej
Only one XHR object should be allowed to gain extra connection
status per
document per server. Each document in the browser may be permitted
one extra
connection per server. Within a document if an XHR object has an extra
connection status for domain1.com, no other XHR objects may have extra
connection status for that server until the first XHR object has
terminated
it's connection. However, another XHR object may have extra connection
status to domain2.com. Each document in the browser should have it's
own set
of extra connections for XHR objects. This limitation is intended to
prevent
a vector of denial of service attacks.
To gain extra connection status, the extraConnection property on the
XHR
object can be set to true. When it is set to true, if the XHR object
is
allowed to gain extra connection status (no other XHR objects
currently have
extra connection status in this document for the specified target
server),
the XHR object will be given extra connection status and subsequent
access
to the property will return true. If the XHR object is not allowed
to gain
extra connection status, subsequent access to the property should
return
false. The following is an example of valid usage:
var xhr = new XMLHttpRequest();
xhr.open("GET","/resource",true);
xhr.extraConnection = true;
var succesful = xhr.extraConnection;
Setting the extraConnection property should throw an exception if it
is
called before a URL is provided to the XHR object (through the open
method
or the constructor). The extra connection status remains in effect
until the
connection is closed (by network error on normal termination), at
which point
the property should return false.
Since the extraConnection property usually indicates that the
response will be a
long-lived streaming response, user agents SHOULD NOT pipeline
requests on this
connection unless the author explicitly specifies such pipelines
using pipelining
control (see the Pipelining Control Proposal).
