The rules-Language

The

rules

-Language

rules

rule

2.22

**Figure 2.22:** Structure of the rules configuration file

In the following, we outline the general structure of the rules configuration file. Then follows a detailed description of important language-elements.

rules

: This element is the root element of the rules configuration file. It has no attribute and contains a sequence of

rule

-elements and

ruleGroup

-elements (see figure 2.23).

**Figure 2.23:** W3C XML Schema of the rules-element
$\begin{figure} \begin{small} \begin{verbatim} <xs:element name=''rules''> ... ... </xs:complexType> </xs:element>\end{verbatim} \end{small} \end{figure}$

rule

: The

rule

-element is responsible for defining transformation-actions. A transformation may be a simple text search-and-replace action, the appliance of XSL- or XQuery-stylesheets or the splitting of a large web page or -form. Therefore it can consist of a

searchFor

replaceWith

-element, elements for defining or importing stylesheet-data (named

xsl

and

xquery

), or an element that deals with the splitting and re-layouting of web content,

layoutPage

. It may also contain information regarding the response header, i.e. if or how the header of the HTTP-response should be modified. This is done with the help of one or more

setResponseHeaderField

-elements at the beginning of the rule-definition (see figure 2.24).

**Figure 2.24:** W3C XML Schema of the rule-element
$\begin{figure} \begin{small} \begin{verbatim} <xs:complexType name=''rule''... ...e=''required''/> </xs:complexType\end{verbatim} \end{small} \end{figure}$

ruleGroup

: A ruleGroup is a sequence of references (via the rule's id-attribute) to (previously defined)

rule

-elements (see figure 2.25). With the help of this element, several common rules can be grouped and can in the following be identified and accessed by one unique id.

**Figure 2.25:** W3C XML Schema of the ruleGroup-element
$\begin{figure} \begin{small} \begin{verbatim} <xs:complexType name=''ruleGr... ...=''required''/> </xs:complexType>\end{verbatim} \end{small} \end{figure}$

searchFor

and

replaceWith

: This rule-type deals with simple text search-and-replace transformations. It consists of two text-elements, called

searchFor

and

replaceWith

. The first one defines text to be searched for, while the latter holds the text-data, the search-string is replaced with. Common regular expressions (Java-style, similar to Perl-regular-expressions) are accepted.

xquery

and

xsl

: These elements are responsible for the definition and the import of transformation-stylesheets. Both are of type xscript (see figure 2.26). Because HTML-content has to be converted in well-formed XML before any stylesheet can applied, the xscript-data type provides one attribute (preTransform) to tell the system, if the underlying data has to be ''pretty-printed'' (or ''tidied'') before the transformation process. The body of the

xsl

- and

xquery

-elements consists of one text-element - either

import

, which holds the name of an external-script-file, or

script

, which allows a direct in-place definition of the stylesheet in the text-content of this element (as CDATA). Figure 2.26 shows the W3C XML Schema of the

xscript

-element.

**Figure 2.26:** W3C XML Schema of the xscript-data type (used by elements xsl, xquery and layoutPage
$\begin{figure} \begin{small} \begin{verbatim} <xs:complexType name=''xscrip... ...ault=''true''/> </xs:complexType>\end{verbatim} \end{small} \end{figure}$

layoutPage

: This element is responsible for splitting web pages and -forms and/or adding header- or footer-data to particular pages. When splitting a large page into smaller pieces, we achieve this by summarizing the ''interesting'' parts in groups and subgroups. This grouping is done by adding special group- and subgroup-tags (named

foxy:group

and

foxy:subgroup

) into the (existing) web page. This may be done dynamically (by adding the tags via a foregoing xsl- or xquery-rule) or statically (e.g., when you are the owner of the page). A unique ID is assigned to each group in order of appearance in the original (HTML-)content. Each subgroup has a unique ID for its group (i.e., each first subgroup in a group has ID=1) All documents transformed via layoutPage do accept following URI/URL-parameters:

: ui - allowed values: -1(all), 0(none), 1, 2..
: sg - allowed values: same as ui
: reset - any value allowed, same as ui=-1 & sg=-1

The layoutPage-element has five (integer-)attributes, holding the values for the first and last group-IDs and subgroup-IDs (default for all: -1) and one for defining the default group that should be displayed, when no group-selecting parameter has been provided:

: firstGroup
: lastGroup
: firstSubgroup
: lastSubgroup
: defaultGroup

Possible (optional) child-nodes of this element are defineTag (multiple times), header and footer. The header- and footer-elements are ap-/prepended to every displayed page-fragment (either a group or a subgroup) and may help you with adding dynamic context to our transformation. The header- and footer-scripts are either defined directly (via a script-element) or imported from a file (similar to the xsl- and xquery-rules, see figure 2.26). Furthermore, the user can define her own tags, e.g. to give headers of different groups a different look.

This is done by providing special-tags, which are replaced at runtime with their appropriate value. These special-tags are:

: @currentPage
: @currentGroup
: @currentSubgroup
: @previousGroup
: @nextGroup
: @previousSubgroup
: @nextSubgroup
: @firstGroup
: @lastGroup
: @firstSubgroup
: @lastSubgroup

**Figure 2.27:** W3C XML Schema of the layoutPage-element
$\begin{figure} \begin{center} \begin{small} \begin{verbatim} <xs:complexTy... ... </xs:complexType>\end{verbatim} \end{small} \end{center}\par \end{figure}$

The defineTag-element, which purpose is the definition of special tags, has following attributes:

: name - The name of the tag
: value - The value of the tag
: source - The group, in which the original tag-definition (in the HTML code of the header- or footer-element) should be replaced with the specified value (of the value-attribute).

A self-defined tag has following structure:

$\fbox{@TAGNAME[DEFAULT\_VALUE]}$

We simply describe the usage and meaning of this tag with the help of a short example: Assuming, one has splitted a web page into groups, it may be convenient to have a different header on the first page of the group (e.g. a title- or welcome-text). We define our ''dynamic'' tag as follows:

$\fbox{$<$defineTag name=''welcome'' value=''Welcome to the first page'' source=''1''/$>$}$

The above definition tells the system to replace every @welcome-tag found in the HTML-content with the text ''Welcome to the first page'', - but only if the displayed source-page/group is the first one in the sequence of groups (attribute source=''1'').

On any other pages, the default text is used. This text is defined directly in the HTML-code. The @welcome-tag may be implemented (e.g., in the HTML-code of the header- or footer-element):

$\fbox{@welcome[Group @currentGroup of @lastGroup]}$

As a result, whenever one views the first page/group, the customized welcome-text (i.e., ''Welcome to the first page'') is ahown. In all other cases the default-text (e.g., ''Group 4 of 8'') will be displayed. Figure 2.27 shows the W3C XML Schema of the

layoutPage

-element.

root 2006-05-22