Re: [xsl] String hashing code

[Abel Braaksma <abel.online@xxxxxxxxx>]

Deborah Pickett wrote:
> True, though years of multithread programming has taught me a strong
> aversion to the inherent race condition in non-atomic test-and-create
> operations like this.  It can't possibly be as big a risk as hash
> collision, but it doesn't stop me feeling any less dirty.
>
> As always, perfection is impossible, so ultimately it comes down to how
> much effort I am willing to go to for that extra nine of reliability.

From another angle, not sure whether your system allows this, but 
getting a unique filename, or a unique number or whatever, without the 
use of non-XSLT functions, becomes inherently easy if you can use some 
internet service. In other words: if you can allow for a dependency to 
some internet (intranet or even localhost) web site, you can use that 
for creating a guaranteed-unique name, possibly with the information of 
your original filename.

For instance, I found one internet service that returns a UUID. You can 
do about the same with any method of uniqueness you want:

   <xsl:template match="/" 
xpath-default-namespace="http://www.w3.org/1999/xhtml";>
       <xsl:variable name="filename" 
select="doc('http://www.famkruithof.net/uuid/uuidgen')/html/body/table/tr/td/h3[1]" 
/>
       <xsl:result-document href="{$filename}" >...</xsl:result-document>
   </xsl:template>

(code tested)

Setting up a system to provide a UUID is as simple as using any Windows 
2000 or higher machine, using the following the VBScript (and I am sure 
something equally easy can be done in a Unix-like environment) and put 
it somewhere in the path of IIS. And if you don't like the UUID syntax, 
you can send a parameter along with the filename and let it be MD5'ed, 
of course ;)

' VBScript to create a UUID:
Set TypeLib = CreateObject("Scriptlet.TypeLib")
NewGUID = TypeLib.Guid
WScript.Echo(left(NewGUID, len(NewGUID)-2))


Cheers,
-- Abel Braaksma