AxsJAX Content Navigation Rules (CNR) Reference

Table of Contents

• 1 Introduction
• 2 Data Types
  • 2.1 KEY
  • 2.2 STRING
  • 2.3 ACTION
  • 2.4 INTEGER
  • 2.5 TRIGGER
• 3 CNR Elements
  • 3.1 cnr
  • 3.2 list
  • 3.3 item
  • 3.4 target

1 Introduction

Think of a content rich site as a site with many trails through it. In each trail, there is content. You can greatly improve the usability of a busy pages by providing efficient keyboard navigation to move through these trails. This can be a more effective approach than providing section headings alone as it allows for grouping related content, filtering out content that is not relevant to what the user is immediately interested in, and controlling the granularity of each item in a given trail. The content navigation rule (CNR) system in AxsNav allows you to easily define these trails.

The CNR system is designed to handle cases where not all of the content is present. If a trail that you have defined happens to have no items, then for that instance, the CNR system will discard that trail. Therefore, when you write CNRs, you should do it for the case where all of the content is present.

To make it easier for users to discover the keyboard navigation commands for the page, the CNR system can automatically generate a help string with all the possible commands. This help generation mechanism takes the user's current position into account - it will only report actions that can be done from the present state. Here is some sample code for generating and speaking the help string:

 var helpStr = "The following shortcut keys are available: " +
               axsNavObj.localHelpString() +
               axsNavObj.globalHelpString();
 axsJAXObj.speakTextViaNode(helpStr);

2 Data Types

2.1 KEY

Any character that is letter, number, or punctuation found on the keyboard OR a string that is "LEFT", "DOWN", "UP", "RIGHT", "ENTER", "PGUP", "PGDOWN". Note that the case of the letter will matter - if you only assign "a" to do something, pressing "A" will not cause that to happen.

2.2 STRING

An arbitrary string of text

2.3 ACTION

A string that specifies what action should take place when the AxsNav system navigates to something. If no acceptable action is specified, the default action will take place.

• "CALL:functionName"
  Will call the specified function with what the AxsNav system navigated to as the argument. For example:

   <item action="CALL:foo"> //some/xpath/expression/here </item>
  

  will cause AxsNav to make the call

   foo(currentItemObject)
  

  when AxsNav moves through the items defined by that item element.

2.4 INTEGER

An integer

2.5 TRIGGER

A string that specifies what trigger should cause the AxsNav system to click on a target.

• "listTail"
  Trigger is activated if the user is at the end of the list and tries to go forward.
• "listHead"
  Trigger is activated if the user is at the start of the list and tries to go backward.
• "listEntry"
  Trigger is activated if the user switches to this list.

3 CNR Elements

3.1 cnr

This is the root level element of the CNR file. The cnr element can contain lists and targets.

• next
  Value is a space delimited list of KEYs. Pressing any of these keys will cause the AxsNav to switch to the next list. After the last list, this will loop to the first list.
• prev
  Value is a space delimited list of KEYs. Pressing any of these keys will cause the AxsNav to switch to the previous list. After the first list, this will loop to the last list.

3.2 list

This is a child element of the cnr element. A list is a trail that the user can go through on the page. Lists can contain items and targets.

• title
  Value is a STRING. When the user switches to this list, this is what will be spoken by the AT.
• hotkey
  Value is a space delimited list of KEYs. Pressing any of these keys will cause AxsNav to switch to this list and immediately read the next item of this list.
• onEmpty
  Value is a STRING. If this list is empty and the user tries to access it with a hotkey, the onEmpty string will be spoken by the AT. Note that AxsNav automatically discards empty lists so if there are not hotkeys assigned to the list, it is not necessary to have an onEmpty message.
• next
  Value is a space delimited list of KEYs. Pressing any of these keys will cause the AxsNav to go to the next item in this list. After the last item, this will always loop to the first item.
• prev
  Value is a space delimited list of KEYs. Pressing any of these keys will cause the AxsNav to go to the previous item in this list. After the first item, this will always loop to the last item.
• fwd
  Value is a space delimited list of KEYs. Pressing any of these keys will cause the AxsNav to go to the next item in this list. After the last item, if there is a target element with a trigger of "listTail" for this list, that target will be acted upon. Otherwise, this is the same as the next attribute.
• back
  Value is a space delimited list of KEYs. Pressing any of these keys will cause the AxsNav to go to the next item in this list. After the last item, if there is a target element with a trigger of "listHead" for this list, that target will be acted upon. Otherwise, this is the same as the prev attribute.

3.3 item

This is a child element of the list element. The item element is an xpath expression that returns a set of nodes which belong in the list. If a list has more than one item element, the set of nodes that will be in the list is the union of all the sets of nodes returned by the xpaths of all the item elements.

• index
  Value is an INTEGER. Specifies the first node in the set of nodes returned by the xpath which should be added to the set of nodes for the item. The default is 0 (starts from the first node).
• count
  Value is an INTEGER. Specifies the total number of nodes to add to the set of nodes for the item. The default is to add all of the nodes starting from the 'index'.
• action
  Value is an ACTION. Does the action specified when a node in the set of nodes for the item is navigated to by the AxsNav system. If no action is specified, the default action is to magnify the item if AxsNav is given a magnifier, go to the element associated with the item, speak the element.

3.4 target

This is a child element of the cnr and list elements. The target element is an xpath expression that returns the node that should be clicked. Note that targets in a list can be relative to the items in that list. Thus having:

 <item>
  //p[@class='g']
 </item>
 <target title='Open result' hotkey='ENTER'>
   ./span[@class='w']
 </target>

 getNodesWithXPath("//p[@class='g']")[2]

 getNodesWithXPath("//p[@class='g']/span[@class='w']")[2]

• title
  Value is a STRING. This is used for generating the help string.
• hotkey
  Value is a space delimited list of KEYs. Pressing any of these keys will cause AxsNav to click on the target if the target is active. Targets that are children of the cnr element are active all the time. Targets that are children of the list element are only active when that list item is the current list.
• trigger
  Value is a TRIGGER.
• onEmpty
  Value is a STRING. If there is no target and the user tries to access it, the onEmpty string will be spoken by the AT.

Author: T.V. Raman, Charles L. Chen <raman@google.com, clchen@google.com>

Date: 2008/06/09 11:27:59