Returns
A ColdFusion
format UUID, in the format xxxxxxxx-xxxx-xxxx-xxxxxxxxxxxxxxxx,
where x is a hexadecimal digit (0-9 or A-F). (The character
groups are 8-4-4-16.)
Usage
The ColdFusion
UUID generation algorithm uses the unique time-of-day value, the
IEEE 802 Host ID, and a cryptographically strong random number generator to
generate UUIDs that conform to the principles laid out in the draft
IEEE RFC "UUIDs and GUIDs."
The ColdFusion UUID format
is as follows:
xxxxxxxx-xxxx-xxxx-xxxxxxxxxxxxxxxx (8-4-4-16).
This
does not conform to the Microsoft/DCE standard, which is as follows:
xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx (8-4-4-4-12)
There
are UUID test tools and a user-defined function called CreateGUID,
which converts CFML UUIDs to UUID/Microsoft GUID format, available
on the web at www.cflib.org.
Use
this function to generate a persistent identifier in a distributed
environment. To a very high degree of certainty, this function returns
a unique value; no other invocation on the same or any other system
returns the same value.
UUIDs are used by distributed computing
frameworks, such as DCE/RPC, COM+, and CORBA. In ColdFusion, you
can use UUIDs as primary table keys for applications in which data
is stored in shared databases. In such cases, using numeric keys
can cause primary-key constraint violations during table merges.
Using UUIDs, you can eliminate these violations.
Example
<h3>CreateUUID Example</h3>
<p> This example uses CreateUUID to generate a UUID when you submit the form.
You can submit the form more than once. </p>
<!--- Checks whether the form was submitted; if so, creates UUID. --->
<cfif IsDefined("Form.CreateUUID") Is True>
<hr>
<p>Your new UUID is: <cfoutput>#CreateUUID()#</cfoutput></p>
</cfif>
<form action = "createuuid.cfm">
<p><input type = "Submit" name = "CreateUUID"> </p>
</form>
