Active Channel

~ the eulogy ~

active channel was a 1997 microsoft bet on push. the whole assumption underneath the channel bar was a broadband connection that could pull publisher feeds overnight without the user noticing. in '97 i was 13 in ankara on a 33.6k dial-up that we paid for by the minute. the audience the channel bar was designed for was not me, it was an office desktop with an always-on t1 (close enough).

microsoft submitted the channel definition format to the w3c in march '97 with pointcast as the co-author. the working draft was a xml schema in which a publisher declared a set of urls and a refresh interval, the browser then walked the list overnight and stored the bits locally. internet explorer 4 shipped in september '97 with the channel bar baked into the active desktop shell, and the cdf-aware sites at launch were disney and warner bros., with aol and cbs joining inside the first year. the press kit talked about the web as a delivery channel, the same way television was a delivery channel for cable feeds.

in fairness, for about a year and a half active channel had the shape of a real product. the channel bar was the front door, a click-down panel docked to the left edge of the browser frame. the publisher feeds updated when the modem reconnected overnight, the offline reading mode let you scroll through that morning's news without dialing in. the cnn home page had an active-channel button on it. that was the part broadband audiences actually used.

the broadband assumption was the entire pitch and it was wrong in '98. most browsers were on dial-up where the overnight pre-download was either impossible or expensive per-minute. the broadband audience that did exist was small enough that publishers could not justify the per-channel cdf authoring overhead. by 2000 the channel partners were quietly letting their cdf feeds rot. rss 0.91 from netscape and userland in early '99 had a flatter element set and no licensing question attached. by '02 syndication had shifted to rss almost completely.

internet explorer 7 was the moment microsoft stopped maintaining the cdf stack. the ie7 release on october 18 '06 listed the channel bar as removed and the cdf parser as deprecated. publishers had not really noticed because they had not been publishing to it in years. in those days. push as a delivery model came back later as web push notifications in firefox 44 in january '16, but the active channel name never returned.

~ the dossier ~

~ the rss inheritance ~

cdf and rss were trying to solve the same problem from two corners. cdf was a microsoft-stewarded xml dialect with offline-cache semantics baked in. rss was a flatter element set without the cache layer. for the publisher writing the feed by hand in '98 the choice came down to which parser shipped on more browsers. internet explorer 4 was that parser for cdf, rss had nothing comparable until late '01 when the netscape directory and a few standalone aggregators started picking it up. for whatever reason the format that kept getting simpler won and the format that kept getting more complex did not (close enough).

~ the pointcast tail ~

pointcast was the desktop push client active channel was modeled on. in those days. the pointcast network had been one of the original push success stories in '96 with a screensaver-style ticker delivering news headlines to corporate desktops. pointcast had peaked at about 1.2 million subscribers in '97 and was already in steep decline by the time active channel adopted its format. the company sold to launchpad technologies in '99 and the desktop client shut down a year later. active channel inherited the lineage with the explorer brand grafted on, but the audience for office-desktop push had already moved to email newsletters.

~ what it left ~

nothing in the modern browser stack uses cdf. the format is recorded in the w3c note archive at NOTE-CDFsubmit and that is roughly the whole memorial. the channel bar was a ui pattern microsoft tried again with the live tile in windows 8 and then again with the start panel news feed in windows 10, neither of those used the cdf format either. push as a transport is now web push, with the service worker handling the offline cache that cdf had been trying to build natively into the browser frame.

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