unique id (uid, uuid, guid etc) class needed
in [C++]
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From: Andrew on 14 Dec 2009 23:13 On 11 Dec, 20:16, George Neuner <gneun...(a)comcast.net> wrote: > On Thu, 10 Dec 2009 08:03:21 CST, Andrew > > <marlow.and...(a)googlemail.com> wrote: > >I need a uuid class. After a bit of googling I see that at some point > >there was some work in boost for this but it looks like it will be a > >while before it is generally available. It is not in 1.41.1. Does > >anyone know if there is one available elsewhere? It must be portable > >of course. > I don't know offhand how portable it is, but the uuid implementation > that is in Linux's EXT2/EXT3 filesystem is used by a number of systems > that need global identifiers. See the e2fsprogs package. Doesn't sound very portable to me. Sounds like its Linux-only. That's not even portable among versions of UNIX. And I need something that works on Microsoft Windows. I am using their GUID for RPC routines at the moment. Regards, Andrew Marlow -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
From: George Neuner on 16 Dec 2009 20:32 On Tue, 15 Dec 2009 10:13:55 CST, Andrew <marlow.andrew(a)googlemail.com> wrote: >On 11 Dec, 20:16, George Neuner <gneun...(a)comcast.net> wrote: >> On Thu, 10 Dec 2009 08:03:21 CST, Andrew >> >> <marlow.and...(a)googlemail.com> wrote: >> >I need a uuid class. ... It must be portable of course. > >> I don't know offhand how portable it is, but the uuid implementation >> that is in Linux's EXT2/EXT3 filesystem is used by a number of systems >> that need global identifiers. See the e2fsprogs package. > >Doesn't sound very portable to me. Sounds like its Linux-only. The generic generator claims to be portable to any POSIX platform and it has fairly extensive #ifdefs for different environments (including Windows). There is also a parallel Windows-only generator that is a thin wrapper around the native GUID API. I haven't tried it but I glanced at the code briefly ... the only thing that isn't immediately clear to me is whether the generic generator can create an id without having a NIC available - on desktop OSes the loopback is always available, but I don't know what would happen, for example, on an embedded platform without a network (of course, in that case it would be unlikely that you'd need uuid in the first place). George -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
From: kenneth on 16 Dec 2009 20:32 On Dec 10, 12:03 pm, Andrew <marlow.and...(a)googlemail.com> wrote: > Hello, > > I need a uuid class. After a bit of googling I see that at some point > there was some work in boost for this but it looks like it will be a > while before it is generally available. It is not in 1.41.1. Does > anyone know if there is one available elsewhere? It must be portable > of course. The project I am currently working on uses the UUID stuff > from Microsoft (for RPC). I want to avoid such lock-in. > > uuids are quite tricky to implement from scratch. I tried to do it > myself several years ago, using ideas from the uids in DCE. One of the > problems is in efficiently generating random numbers with a large > period. Plus, they have to be unique across machines where several > processes on several machines may be generating them simulataneously. > This will definately be the case for my app. I reckon this is why such > uids often incorporate elements of the IP or MAC address. That's > tricky to do in a portable and efficient way. Last time I did it I > wound up having to interrogate the ethervard card using int86 > (uurrgghh) on windows and using ioctl for solaris (eeuuggh). > > Regards, > > Andrew Marlow > Hi, I have implemented a class that generates random UUIDs using system supplied (pseudo)random numbers, /dev/urandom in Unix and the CryptoApi in Windows, which AFAIK should be at least cryptographically strong. I tested it in Linux, Solaris and Windows. As you noted, implementing a portable generator that uses MAC and time is a very difficult, if not impossible, task. Besides, even if this is available, things like virtualization can easily spoil a solution otherwise considered secure. http://sourceforge.net/projects/ooid/ HTH, Kenneth -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
From: Joshua Maurice on 16 Dec 2009 21:02 On Dec 15, 11:13 am, Andrew <marlow.and...(a)googlemail.com> wrote: > On 11 Dec, 20:16, George Neuner <gneun...(a)comcast.net> wrote: > > > On Thu, 10 Dec 2009 08:03:21 CST, Andrew > > > <marlow.and...(a)googlemail.com> wrote: > > >I need a uuid class. After a bit of googling I see that at some point > > >there was some work in boost for this but it looks like it will be a > > >while before it is generally available. It is not in 1.41.1. Does > > >anyone know if there is one available elsewhere? It must be portable > > >of course. > > I don't know offhand how portable it is, but the uuid implementation > > that is in Linux's EXT2/EXT3 filesystem is used by a number of systems > > that need global identifiers. See the e2fsprogs package. > > Doesn't sound very portable to me. Sounds like its Linux-only. That's > not even portable among versions of UNIX. And I need something that > works on Microsoft Windows. I am using their GUID for RPC routines at > the moment. Well, let's assume each system has its own specific GUID call. To make a portable one, couldn't you just write something like: string makeNewGUID() { #ifdef WIN32 string const x = WindowsGUIDCall(); return "win32" + x; #elif defined Linux string const x = LinuxGUIDCall(); return "Linux" + x; //etc. #else #error #endif } Aka: Add a prefix for each particular implementation to avoid collisions. Given that each platform implementation avoids collisions with itself, then your new function will avoid collisions across all platforms. However, this assumes the existence of such a system function on each platform, and it assumes that each implementation is correct. -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
From: Mathias Gaunard on 18 Dec 2009 07:43 On 10 d�c, 14:03, Andrew <marlow.and...(a)googlemail.com> wrote: > Hello, > > I need a uuid class. After a bit of googling I see that at some point > there was some work in boost for this but it looks like it will be a > while before it is generally available. It is not in 1.41.1. It's pending review. It's already available, it's just not into a boost release yet. -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
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