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Re: [Tm4j-developers] configuring in-memory topic map provider base locator
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From: Kal A. <ka...@te...> - 2004-09-27 07:30:23
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Hi Conal,
I'll have to look into why the xml:base attribute is not affecting the
base locator of the topic map (I have a suspicion that it is to do with
the way that the SerializedTopicMapSource works). What you suggest
(adding a base attribute to the <import> element) is a good idea as a
workaround.
Another possible workaround is to make use of a catalog file. TM4J
supports redirection through a catalog, so you can specify that the
filesystem location for topic map http://foo.xtm is
/path/to/xtmfile.xtm. The http:// URI will be used as the topic maps
base locator even thought the topic map is read from the local
filesystem.
So there are a lot of options, but I agree that we should fix the
xml:base processing for the simple case where a SerializedTopicMapSource
reads a single XTM file.
Cheers,
Kal
On Mon, 2004-09-27 at 07:16, Conal Tuohy wrote:
> 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".
>
> 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="nzetc" file="/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 = imp.getAttribute(CONFIG_IMPORT_FILE);
> String name = imp.getAttribute(CONFIG_IMPORT_NAME);
> String realPath = m_context.getRealPath(file);
> File f = new File(realPath);
> try {
> SerializedTopicMapSource tmSrc = new SerializedTopicMapSource(f);
> TopicMap tm = 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 = 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="nzetc" base="http://www.nzetc.org/tm/nzetc.xtm" file="/nzetc/tm/export/nzetc.xtm"/>
>
> In the TopicMapManagerComponent this would be something like:
>
> private void configureImport(TopicMapProvider provider, Configuration imp) throws ConfigurationException
> {
> String file = imp.getAttribute(CONFIG_IMPORT_FILE);
> String name = imp.getAttribute(CONFIG_IMPORT_NAME);
> String base = imp.getAttribute(CONFIG_IMPORT_BASE); // need to add this field
> String realPath = m_context.getRealPath(file);
> File f = new File(realPath);
> try {
> baseLocator = provider.getLocatorFactory().createLocator("URI", base); // convert to locator
> SerializedTopicMapSource tmSrc = new SerializedTopicMapSource(f, baseLocator); // set base locator
> TopicMap tm = 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
>
>
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--
Kal Ahmed <ka...@te...>
techquila
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