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 PointCast: Dr. Doolittle's Pushme-Pullyou? By Bruce Robertson Remember the beast with two heads in The Adventures of Dr. Doolittle? Pushme-pullyou. Well, we're seeing two-headed monsters on the Internet daily. Every time people say they're implementing a push model for content distribution, you have to ask if they're just talking out of two heads. I'm going to use PointCast as an example of how popularity can spell disaster for networks and IS network managers. When PointCast's cool little screen saver hit the Internet streets a while back, it spread like wildfire. Everyone wanted a copy so that weather maps, stock quotes, sports scores, industry updates and news would scroll across the desktop automatically and keep the user updated. It's free (or rather, advertiser supported, which isn't exa ctly the same thing). Great idea, no doubt.
Any other casting neologisms--Web casting, narrowcasting, broadcasting and so on--should be suspect. My advice: Look each gift horse in the mouth. Carefully. It might bite. It may be pulling instead of pushing--or pushing inefficiently--and thus may be pulling network performance down the drain. Problem #1: The Internet File Server Syndrome Users were downloading PointCast right and left. Networ king people inside corporations noticed. Just the downloading across the over-used Internet 56-Kbps line was slowing things, just as whenever there is a new version of browsers like Netscape Navigator or Microsoft Internet Explorer to download. Networked organizations may as well admit that the Internet, once connected, becomes a huge file server for applications over which the networking IS personnel no longer have much control. Even with a firewall, how can you stay up to date with restrictions on download locations? Pesky users will move quicker than most firewall management teams, so loopholes and traffic excesses will always exist. Proactive one-time downloading of programs can help. This way, you download what the user is looking for once to your own internal server, then let users pull their copies from there. You even could distribute it across your own network to key file servers from which users could download. But this pull-first file server strategy will work only if you maintain it proac tively and advertise it well internally; otherwise users could bypass whatever mechanism you've put in place and just download it off the remote FTP site. There also can be legal ramifications in having local copies or mirrors for certain application binaries, so be careful about instituting such an approach without consulting application providers. Problem #2: The Internet Application Server Syndrome After the application has been installed, PointCast has another impact. Users configure the content they'd like to see, and the PointCast client just starts downloading it from the PointCast server on the Internet. Network managers noticed this, too. Many immediately had corporate Internet service provider (ISP) links pegged at 100 percent saturation. Quick work by dedicated networking IS personnel pinpointed the culprit. Users were accessing that PointCast server over and again. With all that traffic funnelled through the Internet link, it naturally went belly up and threw off critical systems suc h as Simple Mail Transfer Protocol (SMTP) mail traffic. The reason is that PointCast's client (even the latest 1.2 client version) still has user-configurable options that decide when the client will pull down data from the server. Des pite all the discussion of content push, the application is still pulling to each client. (At least it pulled only new data.) If a bunch of users want the weather map (multimedia content!), then they all get it. Individually.
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However, the original and even the updated versions of the PointCast distribution system are still pretending pull is push. PointCast is a pull animal trying to pass itself off as a push animal. Unlike more recent start-ups in the Web casting and personalized information publishing solutions, which are true Dr. Doolittles with two-headed llamas, they are at least moving ahead to address some architectural weaknesses that have kept corporations from implementing them.
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by Patricia Schnaidt FreeWire by Bill Frez za Coporate View by Robert Moskowitz On The Wire by Bill Alderson and J. Scott Haugdahl Updated January 24, 1997 |
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