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<DIV dir=ltr align=left><SPAN class=684192808-03102008><FONT face=Arial
color=#0000ff size=2>The point of my message is that if it's taking 1 second to
get the file over the network and 1msec to process the file, then improving the
processing speed to 0.9 msec is a waste of effort. It's like tuning your car's
engine and leaving the handbrake on. You need to understand the overall system
performance (and the extent to which it falls short of the performance
requirements) before you decide which parts of it to tune.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=684192808-03102008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=684192808-03102008><FONT face=Arial
color=#0000ff size=2>Michael Kay</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=684192808-03102008><FONT face=Arial
color=#0000ff size=2><A
href="http://www.saxonica.com/">http://www.saxonica.com/</A></FONT></SPAN></DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> Praveen Gattu [mailto:pgattu@gmail.com]
<BR><B>Sent:</B> 03 October 2008 01:32<BR><B>To:</B> Michael Kay<BR><B>Cc:</B>
Paul Libbrecht; jdom-interest@jdom.org<BR><B>Subject:</B> Re: [jdom-interest]
Re: Reading XML with JDOM<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV dir=ltr>Michael
<DIV><BR></DIV>
<DIV>The XML is to be obtained over a www URL. Our networks are T1 speed and
performing their best. There isn't a problem with the network latency, but I
acknowledge that retrieving the XML file over a www URL is probably the most
time consuming procedure for my application. Www Network latency aside, I want
to assure that whatever APIs/frameworks I use for parsing the XML are the
fastest. For the purposes of measuring the performance of the parser, I am
using a XML file located in the file system and removing the network latency
aspect. Is this a valid method to measure the parser's performance?</DIV>
<DIV><BR></DIV>
<DIV>-- Praveen<BR><BR>
<DIV class=gmail_quote>On Thu, Oct 2, 2008 at 3:49 PM, Michael Kay <SPAN
dir=ltr><<A
href="mailto:mike@saxonica.com">mike@saxonica.com</A>></SPAN> wrote:<BR>
<BLOCKQUOTE class=gmail_quote
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<DIV>
<DIV dir=ltr align=left><SPAN><FONT face=Arial color=#0000ff size=2>You're
asking about how to read the data efficiently with JDOM, but I suspect that
if you are looking for performance then you might be looking in the wrong
part of your system.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN><FONT face=Arial color=#0000ff size=2>XML
parser start-up costs can be very high; initializing the parser for each
document could easily turn out to be the dominant cost in this application.
You can get a lot of saving by reusing parser instances. I don't know what
JDOM's initialization costs for building a document are, but you need to
check them too.</FONT></SPAN></DIV>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2>At any rate, building a
JDOM tree almost certainly takes longer than extracting the data from the
tree once built.</FONT></SPAN></DIV>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2>I find this statement a bit
worrying:</FONT></SPAN></DIV>
<DIV class=Ih2E3d>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV><SPAN>>Anyway, since there is probably not much I can do with the
network latency, I am trying to keep the Java code as skinny and efficient
as possible.<BR></SPAN></DIV></DIV>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2>That seems to be an
inversion of the way performance engineering should be done. If network
latency is the dominant cost, then effort spent on tuning your Java code is
a total waste of time.</FONT></SPAN></DIV>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2>I would focus your
attention on measuring performance, end to end, before you start tuning
anything.</FONT></SPAN></DIV>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2>Michael
Kay</FONT></SPAN></DIV>
<DIV><SPAN><FONT face=Arial color=#0000ff size=2><A
href="http://www.saxonica.com/"
target=_blank>http://www.saxonica.com/</A></FONT></SPAN></DIV>
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<FONT face=Tahoma size=2><B>From:</B> <A
href="mailto:jdom-interest-bounces@jdom.org"
target=_blank>jdom-interest-bounces@jdom.org</A> [mailto:<A
href="mailto:jdom-interest-bounces@jdom.org"
target=_blank>jdom-interest-bounces@jdom.org</A>] <B>On Behalf Of
</B>Praveen Gattu<BR><B>Sent:</B> 02 October 2008 23:04<BR><B>To:</B> Paul
Libbrecht<BR><B>Cc:</B> <A href="mailto:jdom-interest@jdom.org"
target=_blank>jdom-interest@jdom.org</A><BR><B>Subject:</B> Re:
[jdom-interest] Re: Reading XML with JDOM<BR></FONT><BR></DIV>
<DIV>
<DIV></DIV>
<DIV class=Wj3C7c>
<DIV></DIV>
<DIV dir=ltr>Paul,<BR><BR>Thanks for the response. My XML is really as
simple as the one I posted. The 8,500 documents are retrieved over a HTTP
URL. So add network latency, which makes it longer than a minute, unless
my XML parser is extremely fast. Anyway, since there is probably not much
I can do with the network latency, I am trying to keep the Java code as
skinny and efficient as possible.<BR><BR>Would you be able to provide
sample code for the solution you suggested?<BR><BR>
<DIV class=gmail_quote>On Thu, Oct 2, 2008 at 2:27 PM, Paul Libbrecht
<SPAN dir=ltr><<A href="mailto:paul@activemath.org"
target=_blank>paul@activemath.org</A>></SPAN> wrote:<BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">Praveen,<BR><BR>in
jdom you would just parse then take the root, then the employee, the
extract last-name and ssn.<BR>It is ignoring from the point of view of
your programme but not from the point of view of parsing.<BR><BR>Where
you can save is by changing the xml technology... if your document is as
simple as below then using sax has greater performance guarantees (you
really cannot go faster) but is harder to programme with.<BR>Another
part where jdom can take too much of your CPU is if this document has
loads of other stuffs.<BR><BR>Where JDOM would make a positive
difference is at walking more elaborate xml documents, which is the
norm, and at manipulating them. The expressivity of the library there is
unbeatable to my taste.<BR><BR>However, your requirements sound easy:
8500 such documents per minutes?<BR>JDOM does this probably ten times,
multithreadedness not being really necessary.<BR><BR>paul
<DIV>
<DIV></DIV>
<DIV><BR><BR>On 02-oct.-08, at 20:29, Praveen Gattu
wrote:<BR><BR></DIV></DIV>
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<DIV>
<DIV></DIV>
<DIV>I have a XML as below. There is always "only one" employee node
in the XML. So rather than iterating through the nodes, I want to read
the lastname and ssn directly, while ignoring the firstname. What is
the best way to do this in JDOM? My most important criteria is speed.
We will be processing about a 8,500 of such XML documents per minute
(multi-threaded of course) and need something efficient and
fast. I appreciate any help you can offer in this
regard.<BR><BR><response><BR> <employee><BR>
<firstname>John</firstname><BR>
<lastname>Smith</lastname><BR>
<ssn>111-11-1111</ssn><BR> </employee><BR></response><BR><BR>--
<BR>Thanks,<BR>Praveen<BR><BR><BR><BR><BR>--
<BR>Thanks,<BR>Praveen<BR></DIV></DIV>_______________________________________________<BR>To
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