Linking Pages

In Website, the website pages are separate XML documents, so it is not possible to use xref or link to make links between them. Instead, you must use olink[1].

Olink differs from other linking elements because it requires two attributes: one to locate the document and one to locate an ID value within that document. Here is an example of an olink:

<olink targetdoc="home" targetptr="whatsnew"/>
  • The targetdoc attribute identifies the document that contains the target of the link. In Website, the id attribute value on the webpage element used as the document identifier since it must be unique. Its value should be used in the targetdoc attribute of an olink.

  • The targetptr attribute must match an id attribute value on an element within that document. If you want to link to the top of the page, then the targetptr is the same as the targetdoc value.

  • If an olink has no content, then the stylesheet generates content in a manner similar to an xref. The content comes from a website database document that the stylesheets can create. If an olink element has content, then that is used instead of the generated content.

  • Once you enter olinks in your webpages, you need to make sure the right parameters are set to process them.

Olinks with XSLT build method

Here is how you process a website with olinks using the method.

  1. Create your layout.xml file the same as before.

  2. Process your layout.xml file as before with the autolayout.xsl stylesheet to create the autolayout.xml file.

  3. Process your autolayout.xml file as before with either the chunk-tabular.xsl or chunk-website.xsl stylesheet. But set the parameter collect.xref.targets to the value “yes”. That will generate a database file named website.database.xml in the current directory, and use that to resolve olinks.

Olinks with Make method

Here is how you process a website with olinks using the method.

  1. Create your layout.xml file the same as before.

  2. Do the autolayout.xml and depends processing steps as before.

  3. Generate the website database file by processing your autolayout.xml file with the website-targets.xsl stylesheet, saving the output to a file named website.database.xml.

  4. Process your website as you would normally (usually by typing make website).

Here is a sample Makefile using xsltproc and XML catalogs:

PROC = XML_CATALOG_FILES=../catalog.xml  xsltproc

        make website

include depends.tabular

autolayout.xml:  layout.xml
        $(PROC) \
        --output  $@ \
        autolayout.xsl  $<

        make depends

depends:  autolayout.xml
        $(PROC) \
        --output depends.tabular \
        --stringparam  output-root  htdocs  \
        makefile-dep.xsl  $<

website.database.xml:  autolayout.xml
        $(PROC) \
        --output $@ \
       website-targets.xsl  $<

%.html: autolayout.xml 
        $(PROC) \
        --output $@  \
        --stringparam  output-root  htdocs
        tabular.xsl  \
        $(filter-out autolayout.xml,$^)

Olinks with system entities

The original system for olinks uses SYSTEM entities referenced by a targetdocent attribute instead of a targetdoc attribute. And it uses the localinfo attribute instead of targetptr to locate a reference point within the document. Here is how you process the original kind of olinks with Website.

  1. Create an entity declaration that identifies the target page. For example, to link to this page, I would use the following declaration:

    <!ENTITY linking SYSTEM "olink.xml" NDATA XML>

    The name that you use for the entity, linking in this case, is irrelevant. The important thing is that the entity point to the right page. I've used a system identifier here, but you could also use public identifiers if you wanted more flexibility.

    Keep in mind that the systen identifier specified here must be either an absolute URI or a relative URI that will resolve to the target page (in other words, you may need to prefix it with a partial path name, if you keep your XML webpages in different directories).

  2. Make sure the webpage that you are linking from (you don't have to do anything special to the page you're linking to) has a “DOCTYPE” declaration with an internal subset. If your olink entity is the only thing in it, it should look like something like this:

    <!DOCTYPE webpage PUBLIC "-//SF DocBook//DTD Website V2.0//EN"
              SYSTEM " [
    <!ENTITY linking SYSTEM "olink.xml" NDATA XML>

    If you want to link to several different pages, you will need an entity declaration for each of them.

  3. Use the targetdocent attribute of olink to identify the entity of the page you want to link to:

    <olink targetdocent="linking">link text</olink>

    That will link to the correct page in the resulting website. If you want to link to a specific anchor in that web page, use the localinfo attribute to specify the XML ID.

[1] It's also possible to use ulink and make links directly to the generated HTML pages, but that's a bad idea; if you change the hierarchy or rename a page, the link will become stale. With olink this won't happen.