tm4j-developers

[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

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

[Kal A. <ka...@te...>]

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