[LINK] WebSockets

Kim Holburn kim at holburn.net
Wed Mar 30 22:57:17 AEDT 2011

On 2011/Mar/30, at 10:48 PM, Roger Clarke wrote:

> At 22:28 +1100 30/3/11, Johann Kruse wrote:
>> WebSockets-like functionality has definitely been around for some time...
> Tickertape since 1996 for starters.  Although it died, so I guess it 
> isn't around.  Fair enough.
>> For example Exchange Activesync (aka EAS) which is the push-email
>> protocol used by Exchange, iPhone, Android, Windows Phone, etc was
>> introduced around 2005.
>> EAS uses an extended time-out HTTPS session so that the client
>> maintains a connection to the Exchange Server, which can then
>> instantly respond to the already-open session when new email arrives.
>> Because the client is listening but not sending any traffic until the
>> timeout, there is no excess bandwidth consumption.
>> It's not WebSockets - but to the end-user it's the same effect.
> What's an "extended time-out HTTPS session"?

I expect he means a TCP stream using a kind of embraced and extended HTTPS apps layer protocol except instead of a browser at the client end you have an exchange client and instead of a webserver at the server end you have an exchange server.  So they can extend the protocol in a proprietary way and there's no interoperability problems with other software.  And like http you can keep the connection open for as long as you like.

> Aren't sessions established and run at the next level, TCP?


> So all this is is a long TTL?

No, I don't think that's what TTL is about at all.

> That probably wasn't in Vint Cerf's original spec in 1982-83, but I 
> suspect that it long predates the Web, and is independent from it, 
> even in its intellectual origins?
> Sorry, but it's too late at night for an old bastard to do his 
> homework and run the history of TCP TTL to ground  (:-(}
> -- 
> Roger Clarke                                 http://www.rogerclarke.com/
> Xamax Consultancy Pty Ltd      78 Sidaway St, Chapman ACT 2611 AUSTRALIA
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> mailto:Roger.Clarke at xamax.com.au                http://www.xamax.com.au/
> Visiting Professor in the Cyberspace Law & Policy Centre      Uni of NSW
> Visiting Professor in Computer Science    Australian National University
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Kim Holburn
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