RE: [unrev-II] Jack's Use Case: Context-sensitive representation

From: Gil Regev (
Date: Thu Oct 26 2000 - 14:28:33 PDT

  • Next message: Eric Armstrong: "Re: [unrev-II] X-Path and more"

    Unless I am missing the point, it seems to me that this problem was solved
    long ago by distributed system middleware such as CORBA and DCOM. They use
    so called GUID's which contain a locally generated time stamp appended to
    the network card identifier which is guaranteed to be a unique number for
    each machine. Any windows system is able to generate a GUID on demand
    although not from Java 1.1 applets. I don't know about Java 2 but I suspect
    that there must be a security problem with accessing the network card
    number. Anyway, if the id's are generated on the server (be it a local
    server for p2p), it's not a problem. There are several Web applications that
    use GUID's generated on client systems to insure that id's stored in the
    server database are unique.

    I googled the stuff a bit and found a dead IETF draft concerning GUID's and
    the explanation of why it died and a hint that in the future we won't be
    embedding the network card address in the GUID:


    P.S. Eric, did you check WebDAV for hints on versioning?
      -----Original Message-----
      From: Eric Armstrong []
      Sent: jeudi, 26. octobre 2000 22:31
      Subject: Re: [unrev-II] Jack's Use Case: Context-sensitive representation

      Jack Park wrote:
    > The topic maps folks do this with a *public subject* which is being
    > defined as a registered URN. Registering URNs doesn't appear to be
    > all that easy.
    > In a closed system, you just start with the number 0, grab a couple of
    > numbers for some reserved things, then start giving every concept a
    > new, unique number. Pointrel does this. I suppose you'll need to use
    > integers to pull that off, but, what the heck. Problem is, you cannot
    > share with others; that requires grabbing numbers from some registry.
    > Unique URLs
      I'm delighted to say that I have solved this problem, at least in
      principle. The combination of a globally unique userID (say
      plus a globally unique systemID (say, IP address) that includes a CPU
      identifier, in a multiple CPU system, plus a synchronized,
      miliisecond-level time stamp, produces a globally unique node ID.
      That mechanisms allows peer-to-peer node sharing.

      It seems like a lot of information, but except for the time-stamp,
      nodes only need pointers to shared IDs, so the resource requirements
      aren't too extreme.

      [Note: If I can *just* get the rest of the versioning process worked
      out, I'll have an announcement soon.]

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