No subject
Fri Aug 6 17:04:17 PDT 2004
allows 'parentless' implementations. On the other hand, you will have to =
roll your own Node and Element implementations.
/pmn=20
-----Original Message-----=20
From: Martin Schulz [ mailto:schulz at videotron.ca]=20
Sent: Monday, November 11, 2002 2:45 AM=20
To: jdom-interest at jdom.org=20
Subject: [jdom-interest] Reusable JDOM Elements=20
Hi,=20
in a potentially busy server environment, I preconstruct and cache =
potentially many JDOM subtrees. Comes usage time, the subtree gets =
cloned and attached to a real Document, which is subsequently output to =
XML and sent out.
It appears wasteful to have to clone the Elements, even if they are not =
going to be changed, for the sole reason that they maintain a reference =
to their parent. It seems also to be slightly convoluted to manage =
recycling of such subtrees.
Is there a good pattern or solution out there (JDOM or closely related) =
which allows me to build Document trees, which are only top-to-bottom =
connected or which allows to reuse the constant subtree(s) easily?
Thanks!=20
Martin=20
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<META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; =
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<TITLE>Message</TITLE>
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<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN =
class=3D536143804-12112002>We do=20
something very similar in our application to what you're asking. =
When I=20
saw your question, I was curious to see the responses. Unless I=20
misunderstood you're situation you would like a cache of documents that =
you can=20
reuse to fulfill parts of various requests.</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D536143804-12112002></SPAN></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN =
class=3D536143804-12112002>This=20
naturally implies though that you will require 2 copies of the document: =
one to=20
stay in the cache, and one to fulfill the request. Unless you =
don't need=20
to modify the document (or subtree) and you can pass it by reference in =
the=20
response. However, from your email, it sounds like you need a =
totally new=20
copy for the response. In that case I guess what you're trying to =
do is=20
just increase performance. I think the cache idea is good but I =
wonder if=20
you could also create an object pool. If possible, you might set a =
depth=20
for that pool that is maintained by another thread. Having that =
thread=20
keep the pool full in the background might allow for immediate responses =
to a=20
request. Of course this all depends on having enough resources and =
such.</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D536143804-12112002></SPAN></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN =
class=3D536143804-12112002>Just=20
so you know, we pretty much always clone or detach the trees we want to=20
use. If you find a better way let me know.</SPAN></FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3D"Arial Narrow" size=3D2><STRONG>ANDRES =
MARCH</STRONG></FONT></DIV>
<DIV><FONT face=3D"Arial Narrow" size=3D1>LEAD APPLICATION =
DEVELOPER</FONT></DIV>
<DIV><FONT face=3D"Arial Narrow" color=3D#000080 =
size=3D2>eHEALTHCONTRACTS,=20
INC.</FONT></DIV>
<DIV><FONT face=3D"Arial Narrow" size=3D1><A=20
href=3D"http://www.ehealthcontracts.com/">WWW.eHEALTHCONTRACTS.COM</A></F=
ONT></DIV>
<DIV><FONT face=3D"Arial Narrow" size=3D1>OFFICE: 510.581.5646 =
x205</FONT></DIV>
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<DIV>
<P style=3D"MARGIN-BOTTOM: 3px"><FONT face=3D"Arial Narrow"=20
size=3D2><EM>Note:</EM></FONT></P>
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Narrow"=20
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<P style=3D"MARGIN-TOP: 0px"><FONT face=3D"Arial Narrow" =
size=3D2><EM>Thank you.=20
eHealthContracts, Inc.</EM></FONT></P></DIV>
<BLOCKQUOTE dir=3Dltr style=3D"MARGIN-RIGHT: 0px">
<DIV class=3DOutlookMessageHeader dir=3Dltr align=3Dleft><FONT =
face=3DTahoma=20
size=3D2>-----Original Message-----<BR><B>From:</B> Martin Schulz=20
[mailto:schulz at videotron.ca]<BR><B>Sent:</B> Monday, November 11, 2002 =
5:37=20
PM<BR><B>To:</B> jdom-interest at jdom.org<BR><B>Subject:</B> RE: =
[jdom-interest]=20
Reusable JDOM Elements<BR><BR></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002>Henry,</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002></SPAN></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002>could you elaborate just a=20
little?</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002></SPAN></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN =
class=3D870072701-12112002>A=20
straight forward reference counting implementation would be intrusive, =
wouldn't it?</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN =
class=3D870072701-12112002>Then=20
we would still have the problem that an element (or any other 'node') =
can just=20
have one parent...</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002></SPAN></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN =
class=3D870072701-12112002>Am I=20
correct in assuming that you used an external reference holder, which =
was=20
then used to identify and detach the recyclable=20
pieces?</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002></SPAN></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN =
class=3D870072701-12112002>Now=20
for me that would only be half of the solution, as I would have to =
provide=20
either a pooling solution for multiple</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002>copies of these pieces, or implement a=20
synchronization point for resource access.</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002></SPAN></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN =
class=3D870072701-12112002>Also=20
was there a performance gain obtained in your =
solution?</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002></SPAN></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002>Thanks!</SPAN></FONT></DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002></SPAN></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN=20
class=3D870072701-12112002> =
Martin</SPAN></FONT></DIV>
<BLOCKQUOTE dir=3Dltr style=3D"MARGIN-RIGHT: 0px">
<DIV></DIV>
<DIV class=3DOutlookMessageHeader lang=3Den-us dir=3Dltr =
align=3Dleft><FONT=20
face=3DTahoma size=3D2>-----Original Message-----<BR><B>From:</B>=20
jdom-interest-admin at jdom.org [mailto:jdom-interest-admin at jdom.org] =
<B>On=20
Behalf Of </B>Henry Charlton<BR><B>Sent:</B> November 11, 2002 3:02=20
PM<BR><B>To:</B> jdom-interest at jdom.org<BR><B>Subject:</B> RE:=20
[jdom-interest] Reusable JDOM Elements<BR><BR></FONT></DIV>
<P><FONT size=3D2>In the past, I have successfully combined JDOM =
Elements with=20
reference counting. </FONT></P>
<P><FONT size=3D2>Once the xml file was generated, I would traverse =
the=20
document from the root element, making detach() calls.</FONT> =
</P><BR>
<P><FONT size=3D2>--Henry</FONT> </P><BR><BR>
<P><FONT size=3D2>-----Original Message-----</FONT> <BR><FONT =
size=3D2>From:=20
Norrman Per [<A=20
=
href=3D"mailto:per.norrman at canovia.se">mailto:per.norrman at canovia.se</A>]=
=20
</FONT><BR><FONT size=3D2>Sent: Monday, November 11, 2002 4:25 =
AM</FONT>=20
<BR><FONT size=3D2>To: 'Martin Schulz'; =
jdom-interest at jdom.org</FONT>=20
<BR><FONT size=3D2>Subject: RE: [jdom-interest] Reusable JDOM =
Elements</FONT>=20
</P><BR>
<P><FONT size=3D2>Hi,</FONT> </P>
<P><FONT size=3D2>From a quick glance, it appears that dom4j (<A=20
href=3D"http://www.dom4j.org" =
target=3D_blank>http://www.dom4j.org</A>)=20
</FONT><BR><FONT size=3D2>allows 'parentless' implementations. On =
the other=20
hand, you will have to roll your own Node and Element=20
implementations.</FONT></P><BR>
<P><FONT size=3D2>/pmn</FONT> </P>
<P><FONT size=3D2>-----Original Message-----</FONT> <BR><FONT =
size=3D2>From:=20
Martin Schulz [<A=20
href=3D"mailto:schulz at videotron.ca">mailto:schulz at videotron.ca</A>]=20
</FONT><BR><FONT size=3D2>Sent: Monday, November 11, 2002 2:45 =
AM</FONT>=20
<BR><FONT size=3D2>To: jdom-interest at jdom.org</FONT> <BR><FONT =
size=3D2>Subject:=20
[jdom-interest] Reusable JDOM Elements</FONT> </P><BR>
<P><FONT size=3D2>Hi,</FONT> </P>
<P><FONT size=3D2>in a potentially busy server environment, I =
preconstruct and=20
cache potentially many JDOM subtrees. Comes usage time, the subtree =
gets=20
cloned and attached to a real Document, which is subsequently output =
to XML=20
and sent out.</FONT></P>
<P><FONT size=3D2>It appears wasteful to have to clone the Elements, =
even if=20
they are not going to be changed, for the sole reason that they =
maintain a=20
reference to their parent. It seems also to be slightly =
convoluted to=20
manage recycling of such subtrees.</FONT></P>
<P><FONT size=3D2>Is there a good pattern or solution out there =
(JDOM or=20
closely related) which allows me to build Document trees, which are =
only=20
top-to-bottom connected or which allows to reuse the constant =
subtree(s)=20
easily?</FONT></P>
<P><FONT size=3D2>Thanks!</FONT> </P>
<P> <FONT =
size=3D2>Martin</FONT>=20
</P><BR>
<P><FONT size=3D2>---</FONT> <BR><FONT size=3D2>Outgoing mail is =
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