mayer@hplabsz.HPL.HP.COM (Niels Mayer) (03/21/90)
(Hi Alan!) I'm not at all familiar with the DB architecture of Lotus Notes... however, a comment you made in your (very helpful) description of that system begs for elabration: In article <WEX.90Mar19131959@sitting.pws.bull.com> wex@sitting.pws.bull.com (Buckaroo Banzai) writes: > - Notes uses a custom, highly-optimized, fully-replicated database to store >documents. Documents are seen through hierarchical views. Views are >predefined for each DB, though users can define "custom views." {this is >their biggest luze, imho. A replicated DB is a disaster waiting to happen. Why is a replicated DB a "luze" for such groupware applications? How would *you* build a DB to share such information? Would your dream system do queries on a remote databases, and have that information come back in "realtime"?? What object granularity would you be able to support? What about situations where notes sites are not connected by fast networks?? Isn't USENET news a slimy form of replicated DB? It seems to work ok... though it doesn't really offer very much functionality. ------------------------------------------------------------------------------- Niels Mayer -- hplabs!mayer -- mayer@hplabs.hp.com Human-Computer Interaction Department Hewlett-Packard Laboratories Palo Alto, CA. *
bdb@becker.UUCP (Bruce Becker) (03/23/90)
In article <4995@hplabsz.HPL.HP.COM> mayer@hplabs.hp.com (Niels Mayer) writes: |(Hi Alan!) | |I'm not at all familiar with the DB architecture of Lotus Notes... however, |a comment you made in your (very helpful) description of that system begs |for elabration: | |In article <WEX.90Mar19131959@sitting.pws.bull.com> wex@sitting.pws.bull.com (Buckaroo Banzai) writes: |> - Notes uses a custom, highly-optimized, fully-replicated database to store |>documents. Documents are seen through hierarchical views. Views are |>predefined for each DB, though users can define "custom views." {this is |>their biggest luze, imho. A replicated DB is a disaster waiting to happen. | |Why is a replicated DB a "luze" for such groupware applications? How would |*you* build a DB to share such information? Would your dream system do |queries on a remote databases, and have that information come back in |"realtime"?? What object granularity would you be able to support? I think the implication is that concurrent reliability and consistency is impossible to achieve in replicated DB's. The overhead to guarantee update consistency across all replications can often equal the overhead of direct query. Granted that some compromises of "guarantee" can be made to improve performance (if everyone understands and agrees to the "gotchas"), but this requires careful design, and usually later redesign if the interconnections change substantially. The bottom line is that if you try to imagine patching up a broken DB on one machine (always a painful process), you need to imagine the much worse problem of reconciling inconsistent views on a large distributed replicated DB - it ought to give one pause... |What about situations where notes sites are not connected by fast networks?? It's true that remote queries can impact remote connections severely in some cases - the usual solutions are some forms of local caching to increase performance, which ends up being a special case of replication (sigh), with many of the attendant problems... |Isn't USENET news a slimy form of replicated DB? It seems to work ok... |though it doesn't really offer very much functionality. I wouldn't call UseNet a reliable DB. If that level of unreliability (which can be pretty poor in terms of consistency and update time skew) is acceptable, then "go for it". I suspect however that groupware has much more stringent requirements in general... -- ,u, Bruce Becker Toronto, Ontario a /i/ Internet: bdb@becker.UUCP, bruce@gpu.utcs.toronto.edu `\o\-e UUCP: ...!uunet!mnetor!becker!bdb _< /_ "Paranoia is its own reward" - W. Disney
consensus@cdp.UUCP (06/03/90)
The following reply is from the Groupware SIG on America Online. For more information, or to reply to an individual on America Online, contact: * Christopher Allen - Consensus Development * P.O. Box 2836, Union City, CA 94587-7836 * AT&T: (415) 487-9206 * America Online: AFL MacDev * AppleLink: D3516 * Internet: cdp!consensus@arisia.xerox.com * UUCP: uunet!pyramid!cdp!consensus **** Subj: What is it, anyway? 90-04-25 01:38:56 EDT From: Shep T Even after reading this entire thread, I'm still not too clear on what Notes is all about. It takes documents from around the net and feeds them to you based on criteria (forms) that you've previously set up? Is this correct? What am I missing? Subj: Lotus Notes 90-04-25 16:39:54 EDT From: AFL MacDev I think the briefest summary is that it is similar to their single user product, Lotus Agenda, except it is multiuser, costs 62K, and has more bells and whistles. I haven't seen it personally, yet. But I hope to before the Electronic Networking Assocation conference in May. Chris Allen - AFL MacDev