Hi,
I'm trying to find out how unique a GUID is?
Basically I have two web applications and I need to pass a couple of
session variables between them using a table in a database. I have set
this up and used a GUID as a key for the table and it all seems to
work fine but I'm a little concerned about the uniqueness of the GUID.
Does anyone know how the GUID is created?
or if it is unique across all applications on a webserver?
Thanks
Davinder
5  9730 
"Davinder" <da************ *@gmail.comschr eef in bericht
news:11******** **************@ y5g2000hsa.goog legroups.com...
Hi,
I'm trying to find out how unique a GUID is?
Basically I have two web applications and I need to pass a couple of
session variables between them using a table in a database. I have set
this up and used a GUID as a key for the table and it all seems to
work fine but I'm a little concerned about the uniqueness of the GUID.
Does anyone know how the GUID is created?
or if it is unique across all applications on a webserver?
Thanks
Davinder
Hi Davinder,
A GUID is GLOBALLY unique.
Trust me: from the moment on this wouldn't be the case anymore, a lot of
applications will get into trouble.
It contains reference to the unique MAC address of the network adapter +
random bytes + date/time etc ...
On Windows NT servers in the past GUIDs produced consecutively GUIDS (unique
still though), but this has changed in future versions of Windows.
Wim
"Davinder" <da************ *@gmail.comschr eef in bericht
news:11******** **************@ y5g2000hsa.goog legroups.com...
Hi,
I'm trying to find out how unique a GUID is?
Basically I have two web applications and I need to pass a couple of
session variables between them using a table in a database. I have set
this up and used a GUID as a key for the table and it all seems to
work fine but I'm a little concerned about the uniqueness of the GUID.
Does anyone know how the GUID is created?
or if it is unique across all applications on a webserver?
Thanks
Davinder
Since it is GLOBALLY unique, you can't be sure that this GUID will not be
re-used on Mars !,
so you might get into trouble if you are planning to use this for message
exchange with aliens ! :-)
Michael, Wim thanks for your replys, the info is very helpful.
after I had written the message I actually did a quick test and
produced 100,000 GUIDs from my web apps and there were no clashes, so
I guess it should all run without any problems.
Since it is GLOBALLY unique, you can't be sure that this GUID will not be
re-used on Mars !,
so you might get into trouble if you are planning to use this for message
exchange with aliens ! :-)
ahh this may cause a problem in the future then! I was planning on
hosting one of the web apps on mars so aliens could use it, guess I'll
have to come up woth a workaround, oh well :o)
Davinder
You should have read the Wikipedia article. You would have saved yourself
some trouble. The probability of 2 GUIDs being the same is about 1 in a
quintillion.
--
HTH,
Kevin Spencer
Microsoft MVP
Printing Components, Email Components,
FTP Client Classes, Enhanced Data Controls, much more.
DSI PrintManager, Miradyne Component Libraries: http://www.miradyne.net
"Davinder" <da************ *@gmail.comwrot e in message
news:11******** **************@ p77g2000hsh.goo glegroups.com.. .
>
Michael, Wim thanks for your replys, the info is very helpful.
after I had written the message I actually did a quick test and
produced 100,000 GUIDs from my web apps and there were no clashes, so
I guess it should all run without any problems.
>Since it is GLOBALLY unique, you can't be sure that this GUID will not be
re-used on Mars !,
so you might get into trouble if you are planning to use this for message
exchange with aliens ! :-)
ahh this may cause a problem in the future then! I was planning on
hosting one of the web apps on mars so aliens could use it, guess I'll
have to come up woth a workaround, oh well :o)
Davinder
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