[Tm4j-developers] configuring in-memory topic map provider base locator

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

I am using the In-Memory topic map provider with Cocoon.

I need to load the topic map from an XTM file into memory, but I want to =
give it a different base locator. I want the base locator of the =
resulting map to be an http url, but I want to read the file from the =
local file system. I thought I could specify an xml:base attribute on =
the topicMap element in the file, but this has no effect, and I end up =
with a topic map with a base locator of "file:// etc".=20

I've had a look at the Cocoon TopicMapManagerComponent code, and there =
seems to be a couple of ways to specify a source in the cocoon.xconf =
file: using a parameter called "tm4j.topicmap.0", or alternatively, =
using an <import> element. I haven't yet looked at the first method =
("tm4j.topicmap.0 parameter") in great detail, but it doesn't seem to =
offer what I want. Neither does the <import> element :-) but it's what =
I've been using so far. It looks like this:

<import name=3D"nzetc" file=3D"/nzetc/tm/export/nzetc.xtm"/>

The TopicMapManagerComponent has a method configureImport which =
processes this:

   private void configureImport(TopicMapProvider provider, Configuration =
imp) throws ConfigurationException
    {
        String file =3D imp.getAttribute(CONFIG_IMPORT_FILE);
        String name =3D imp.getAttribute(CONFIG_IMPORT_NAME);
        String realPath =3D m_context.getRealPath(file);
        File f =3D new File(realPath);
        try {
            SerializedTopicMapSource tmSrc =3D new =
SerializedTopicMapSource(f);
            TopicMap tm =3D provider.addTopicMap(tmSrc);
            m_topicMapNames.put(name, tm.getBaseLocator());
        } catch (Exception ex) {
            getLogger().error("TopicMapManagerComponent: Unable to =
process import named " + name, ex );
            throw new ConfigurationException("Unable to process import =
'" + name + "'", ex);
        }
    }

... so the base locator is set by the SerializedTopicMapSource, which =
makes the locator by converting the java.io.File to a URL, so my base =
locator always equals the URL of the file where I loaded the XTM from:

   locatorString =3D file.toURL().toString();

If this seems like a reasonable requirement (to be able to specify a =
different base locator), I'd like to change the TopicMapManagerComponent =
to read a "base" attribute from the <import> element and pass this to =
the SerializedTopicMapSource constructor along with the file.

e.g.

<import name=3D"nzetc" base=3D"http://www.nzetc.org/tm/nzetc.xtm" =
file=3D"/nzetc/tm/export/nzetc.xtm"/>

In the TopicMapManagerComponent this would be something like:

   private void configureImport(TopicMapProvider provider, Configuration =
imp) throws ConfigurationException
    {
        String file =3D imp.getAttribute(CONFIG_IMPORT_FILE);
        String name =3D imp.getAttribute(CONFIG_IMPORT_NAME);
        String base =3D imp.getAttribute(CONFIG_IMPORT_BASE); // need to =
add this field
        String realPath =3D m_context.getRealPath(file);
        File f =3D new File(realPath);
        try {
            baseLocator =3D =
provider.getLocatorFactory().createLocator("URI", base); // convert to =
locator
            SerializedTopicMapSource tmSrc =3D new =
SerializedTopicMapSource(f, baseLocator); // set base locator
            TopicMap tm =3D provider.addTopicMap(tmSrc);
            m_topicMapNames.put(name, tm.getBaseLocator());
        } catch (Exception ex) {
            getLogger().error("TopicMapManagerComponent: Unable to =
process import named " + name, ex );
            throw new ConfigurationException("Unable to process import =
'" + name + "'", ex);
        }
    }

Alternatively, the SerializedTopicMapSource could parse the source and =
extract the xml:base attribute and use that. In some ways this would be =
preferable.

What do other people think?

Sorry for the long email. I'm not even sure if this is a good idea, but =
it's related to a problem I'm having with subject indicators, which I'll =
post about on the users list.

Cheers

Con