HTML User Interface

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Motivation

The suite of XRL technologies provide all the components necessary to construct flexible and maintainable HTML user interfaces on NetKernel. The benefits are:

complete separation of external URLs from internal services or static resources behind them.
recursive template oriented approach allows maximum reuse of content.
ability to "rewrite" links and img tags to make interface "relocatable".
add module/application specific error handling pages.

Structure

A single rewrite rule is used to map all external requests to the XRL mapper. The mapper uses the default link file resource located at ffcpl:/etc/XRLLinks.xml. Any external request that is not mapped will cause invoke the xrl:404 resource which is mapped to an friendly error page. Both static and dynamically generated results can be returned without exposing their implementing technologies on the interface.

Page resources are mapped to the XRL linker which take a standard template and populate it with data pulled from a data service.

Here is the example module.xml:

<module>
  <!-- put identity/info/publisher/license sections here -->
  <export>
    <uri>
      <match>ffcpl:/my_module/.*</match>
    </uri>
  </export>
  <mapping>
    <!-- rewrite all external requests to xrl mapper -->
    <rewrite>
      <match>(ffcpl:/my_module/.*)</match>
      <to>active:mapper+operand@$1</to>
    </rewrite>
    <!-- make static module resource available -->
    <this>
      <match>ffcpl:/etc/XRLLinks.xml</match>
      <match>ffcpl:/pub/.*</match>
      <match>ffcpl:/page/.*</match>
    </this>
    <!-- import libraries -->
    <import>
      <uri>urn:org:ten60:netkernel:ext:xrl</uri>
    </import>
    <import>
      <uri>urn:org:ten60:netkernel:ext:script</uri>
    </import>
    <super />
  </mapping>
</module>

Here is the example XRLLinks.xml:

<links basepath="ffcpl:/my_module/">
  <!-- example link to static resource from internal address space-->
  <link>
    <name>icon</name>
    <ext>/icon.png</ext>
    <int>ffcpl:/pub/icon.png</int>
  </link>
  <link>
    <name>css</name>
    <ext>/style.css</ext>
    <int>ffcpl:/pub/style.css</int>
  </link>
  <!-- the index page is generated with xrl linker 
            a param argument if available is passed through to sub parts -->
  <link>
    <ext>/index.html</ext>
    <int>active:xrl+template@xrl:my_template+content@xrl:data</int>
    <arg>param</arg>
  </link>
  <link>
    <!-- because the template has no ext specified it isn't exposed externally -->
    <name>my_template</name>
    <int>ffcpl:/page/template.xml</int>
  </link>
  <link>
    <!-- a param argument is passed to the script if available -->
    <name>data</name>
    <int>active:beanshell+operator@ffcpl:/page/data.bsh</int>
    <args>param</args>
  </link>
</links>

Here is the example template.xml:

<html xmlns:xrl="http://1060.org/xrl">
  <head>
    <!-- these are dynamically linked in -->
    <link href="xrl:icon" rel="SHORTCUT ICON" xrl:resolve="href" />
    <link href="xrl:css" rel="stylesheet" type="text/css" xrl:resolve="href" />
    <!-- generate title based on content with a fallback value -->
    <title>
      <xrl:eval fallback="'my_module'" xpath="/html/body//h1/text()" />
    </title>
  </head>
  <body>
    <h1>Here is the data</h1>
    <!-- pull in content here -->
    <xrl:include href="xrl:content" />
  </body>
</html>