Backlink

Try It Out

If you want to check out the Backlink plugin, do the following:

How to setup the plugin:
- This plugin only works with Netscape Navigator 4.x, so you'll need to ensure that that browser is installed
- Start WBI and setup your browser to use WBI as a proxy.
- Register the Backlink plugin on the WBI console by typing (on one line):
  register com/ibm/wbi/examples
  /backlink/backlink .reg
- Check to see whether the plugin is registered and enabled. Go to the WBI Setup page. The Backlink plugin should be listed in the table with a checkmark next to its name. If the plugin is not listed, try registering it again. If the checkmark is not there, click on the box to the left of the plugin name.
- Open another browser window. Use that window to try out the plugin, and use this window to display the documentation. (To open a window using Netscape Navigator, go to File -> New -> Navigator Window.)
How to use the plugin:
- Visit any web site outside your firewall, e.g., The WBI Homepage. Look for the link "[backlinks]" in the top left-hand corner of the browser window. If you click on this link, after a few moments you should see a popup window listing some web pages which contain links to the current page. You can browse to these pages and see who is linking to the current page.

What It Does

The plugin inserts a link into the top of each page with a WBI Editor. When clicked, this link makes a request to a WBI Generator which contacts a search engine which provides a list of backlinks. For the purpose of this example, AltaVista's© Raging Search Engine is used, but any search engine that provides the backlink service could be plugged in easily.

How It Works

Architecture

The Backlink plugin is comprised of two Editors and a Generator. The editors are responsible for inserting the link and Javascript at the top of the document. The plugin uses an AddPreambleEditor, a WBI bean, to simplify this work. The Generator is responsible for contacting the search engine, performing some minimal parsing to discover the backlinks within the search results, and reformating them for display in the small popup window.

In order to produce the popup effect, the proprietary Netscape LAYER tag is used. (Unfortunately the standardized DIV tag implemented in Internet Explorer and Mozilla does not provide any way to set the source attribute, which is required for this example to work.) The javascript switches the visibility of the layer and sets its source to be a URL to which the Generator in this plugin responds.

Some key WBI classes that were used:

Package com.ibm.wbi.protocol.http.beans

AddPreambleEditor Used to insert the link "[backlinks]" on the top of each document and the Javascript code.

Package com.ibm.wbi.protocol.http

HttpGenerator Subclassed by BacklinkGenerator

HttpEditor Subclassed by BacklinkEditor

FetchUrl Used to send a request to the backlink service

Package com.ibm.wbi.markuplanguage.html

HtmlTokenizer Simple parsing of the results from the search engine.

The Source

BacklinkPlugin.java: Contains the class definition for the backlink plugin.
backlink.reg: Contains the necessary code to register the plugin with WBI. Registration is done through WBI during runtime.
index.html: This file.