[TM4J-users] slow tm export

[Conal T. <Con...@vu...>]

I am developing an application which uses tm4j with Hibernate as the =
provider.=20

The application is a website built with Cocoon. The topic map is =
harvested from a bunch of sources, and defines the information =
architecture of the site. Each page on the site represents a topic with =
all its associated topics and other characteristics. So each page =
requires querying for a few topics only. This works OK.

My problem is that I also want to be able to visualise the entire map, =
to check my harvesting/merging/etc; to do this I've exported the entire =
map, and it takes about an hour (on a 2.6GHz P4 with 2GB RAM). This =
seems like a long time to export 838kb of XTM code containing about 2800 =
topics, but only a few dozen associations. Is this to be expected? Or is =
there something peculiar in this? The MySQL database is local, and the =
export is definitely processor-bound. About 97% of the processor time is =
used by Tomcat (which is the container in which tm4j is running), and =
the remainder is used by MySQL.=20

Some people have reported very slow performance with IMPORTING into =
hibernate - I haven't noticed that. Certainly it takes only a minute or =
so to harvest all these topics (which includes transforming them from =
other XML formats into XTM) and insert them into tm4j.

I see now that it's possible to configure TMNav to use the hibernate =
provider - so maybe I don't need to do this export at all. I don't know =
if this will speed up the visualisation - I'm certainly going to try =
that, but I'm still keen to hear if someone can tell me I'm doing =
something wrong - especially if it's something small and easy to fix :-) =


I'm appending the JavaScript code which does the export, calling Java =
classes to do the actual work. This code runs inside of Cocoon, as a =
"flowscript".

Thanks

Con


--
Conal Tuohy
Senior Programmer
New Zealand Electronic Text Centre
www.nzetc.org

JavaScript code:

function export_map() {
	/* this program exports the "nzetc" topicmap to an XTM file, and then =
calls a Cocoon pipeline to display that XTM file */=20

	/* this file to export into */
	var export_filename =3D cocoon.parameters["filename"];
=09
	/* get the topic map from the topic map manager */
	var TopicMapManager =3D =
cocoon.getComponent("org.tm4j.tm4web.cocoon.TopicMapManagerComponent");
	var map =3D TopicMapManager.getTopicMap("nzetc");
	cocoon.releaseComponent(TopicMapManager);

	/* write the topic map to a file */
	var walker =3D new Packages.org.tm4j.topicmap.utils.TopicMapWalker();
	var writer =3D new Packages.org.tm4j.topicmap.utils.XTMWriter();
	var file =3D new java.io.File(export_filename);
	var os =3D new java.io.FileOutputStream(file);
	var of =3D new Packages.org.apache.xml.serialize.OutputFormat();
	of.setEncoding("UTF-8");
	of.setIndenting(true);
	of.setIndent(2);
	var serializer =3D new =
Packages.org.apache.xml.serialize.XMLSerializer(os, of);
	walker.setHandler(writer);
	writer.setContentHandler(serializer);
	walker.walk(map);
	cocoon.sendPage("export/nzetc.xtm");
}