RE: [xsl] XML Dom Caching

[Kanthi <kan_manikoth@xxxxxxxxx>]

HI Jennifer - 

I appreciate the reply.  So it looks I will have to
clone the node if I want to use the cached DOM without
directly making changes to it during the processing of
my code.

i.e Using, set objDOM = Application("CachedXMLData")
will cause the "CachedXMLData" to be altered if objDOM
is altered.  Am I correct in thinking this?

Thanks
Kan

--- Jennifer Phillips <jennifer@xxxxxxxxxx> wrote:
> >Does anyone know whats the best way to cache an xml
> >dom in global.asa [ASP/VBScript] ?
> 
> I dont know about the best way, but the way I do it
> is below...
> 
> >I have a number of XML documents that are used
> extensivly
> >in my code and I did not want to load them each
> time but
> >instead cache it so that I can just call it once
> and
> >keep resuing it.
> 
> Wise move, just be a little careful about the memory
> usage of storing so
> many DOM's in memory, you could end up slowing the
> whole thing down rather
> than speeding it up.
> 
> >Once I cache it what is the best way to call is
> besides
> >Application(strCachedDom).cloneNode(true) ?
> 
> I just set an object reference to the DOM in the
> Application object, however
> this does have one drawback, if you change the DOM
> referenced in the
> variable, you also change the cached version in the
> Application object
> (Since they are the same thing), if you need to
> change the data in the DOM
> you will have to clone it (Unless you want the
> cached version updated also).
> 
> Anyway here's the code.....
> 
> I personally dont start the cache in the Globet.asa,
> because my data is
> updated quite often so each time its hit, it needs
> to check the cache is
> still fresh, so this goes into an ASP page, shouldnt
> be too hard to modify
> to go into the Global.asa.
> 
> ' This IF checks whether we have any cached data or
> we have asked to updated
> it.
> if isEmpty(Application("CachedXMLData")) or _
>    Request("refresh") = "true" then
> 
>      ' load the XML document
>      ' IMPORTANT!!!!!  To be stored in the
> application object it
>      ' MUST be a FreeThreaedDOMDocument NOT a
> DOMDocument
>      set xml =
>
Server.CreateObject("MSXML2.FreeThreadedDOMDocument.4.0")
> 
>      ' Load in the XML
>      call loadXMLFile(xml, "C:\MyData.XML")
> 
>      ' Save it to the Application object
>      call updateAppVariable("CachedXMLData", xml)
>   end if
> end if
> 
> Sub loadXMLFile(xmldoc, filename)
>    if not xmldoc.load(filename) then
>       Response.Write "Error loading the file '" _
>         & filename & "'.<br>"
>       Response.Write "Description: " & _
>         xmldoc.parseError.reason & "<br>"
>       Response.Write "Line: " & _
>         xmldoc.parseError.line & "<br>"
>       Response.Write "Line position: " _
>         & xmldoc.parseError.linepos & "<br>"
>       Response.End
>    end if
> End Sub
> 
> Sub updateAppVariable(varName, value)
>     Application.Lock
> 
>     if isObject(value) then
>        set Application(varname) = value
>     else
>        Application(varname) = value
>     end if
> 
>     Application.UnLock
> End Sub
> 
> 
> Then to retrieve the DOM data....
> 
> set objDOM = Application("CachedXMLData")
> 
> 
> If you are doing a lot of XSLT with the cached XML
> data, its also good to
> store the XSLT template in the application object
> too since then its
> pre-compiled, on the pages I've done this on,
> combined with the XML caching,
> I got a 5 fold performance increase.
> 
> If you have any further questions let me know.
> 
> Jenni Phillips
> 
> 
> 
>  XSL-List info and archive: 
> http://www.mulberrytech.com/xsl/xsl-list
> 


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