3D PLM Enterprise Architecture

About Globally Unique IDentifiers

A Globally Unique IDentifier (GUID) is intended to uniquely identify the interface wherever and whenever this interface is used. It is encoded on 128 bits and is made to be unique over both space and time:

• 48 bits ensure this uniqueness over space by catching the address of the network card on the computer where the command which creates the GUID is run. This address is unique and this guarantees that any GUID generated on a given computer is different from any other GUID generated on another computer.
• A timestamp of 60 bits ensures the uniqueness over time, which represents the count of 100-nanosecond intervals since 00:00:00.00, 15 October 1582. This leaves room to generate GUIDs until approximately AD 3400.

GUIDs where first created as UUIDs, for Universally Unique IDentifiers, by the Open Software Foundation (OSF) for the Remote Procedure Calls (RPC) of the Distributed Computing Environment (DCE). This is the reason why you can find sometimes UUID used instead of GUID, such as in the commands or utilities to generate them.

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How to Get a Globally Unique IDentifier

You can get a GUID for your interface as follows:

• With UNIX, the uuid_gen -C command returns a GUID like the following:

  = { 0x7c7b3737,
      0x5358,
      0x0000,
      0x02,
      {0x80, 0x02, 0x0b, 0x3e, 0x00, 0x00, 0x00} };

  To run this command, enter:

  • /etc/ncs/uuid_gen -C with AIX
  • /usr/sbin/ncs/uuid_gen -C with HP-UX
  • Sun does not provide today any means to generate a GUID

  You need then to do a bit editing to transform it as follows when including it into the interface IDL file: 7c7b3737-5358-0000-0280020b3e000000

  To include it into a C++ file, transform it as follows:

  = { 0x7c7b3737,
      0x5358,
      0x0000,
      {0x02, 0x80, 0x02, 0x0b, 0x3e, 0x00, 0x00, 0x00} };

• With Windows, the command uuidgen -s returns a Global Unique IDentifier as follows:

  INTERFACENAME = { /* 7c7b3737-5358-0000-0280-020b3e000000 */
      0x7c7b3737,
      0x5358,
      0x0000,
      {0x02, 0x80, 0x02, 0x0b, 0x3e, 0x00, 0x00, 0x00}
    };

  For an IDL interface, copy the commented value on the first line, paste it, and remove the last hyphen to get 7c7b3737-5358-0000-0280020b3e000000.

  You can also run the UUIDGEN.EXE which returns only 7c7b3737-5358-0000-0280-020b3e000000. Don't forget to remove the last hyphen.

  To include it into a C++ header file, you can take the hexadecimal values as is.

  = { 0x7c7b3737,
      0x5358,
      0x0000,
      {0x02, 0x80, 0x02, 0x0b, 0x3e, 0x00, 0x00, 0x00}
    };

  Note: uuidgen is usually located in C:\Program Files\Microsoft Visual Studio\Common\Tools

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