Writing Rulesets

For more information about defining a ruleset, see the Portal Server Administration Guide. After creating a new ruleset, you need to define the required rules.

This section covers the following topics:

• Public Interface (RuleSet DTD)

• Sample XML DTD

• Procedure to Write Rules

• Ruleset Guidelines

• Defining the RuleSet Root Element

• Using the Recursive Feature

• Rules for HTML Content

• Rules for JavaScript Content

• Rules for XML Content

• Rules for Cascading Style Sheets

• Rules for WML

Public Interface (RuleSet DTD)

RuleSet DTD:

<?xml version="1.0" encoding="UTF-8"?>
<!--
The following constraints are not represented in DTD, but taken care of programmatically
    1. In a Rule, All Mandatory attributes cannot be "*".
    2. Only one instance of the below elements is allowed, but in any order.
    1)HTMLRules
    2)JSRules
    3)XMLRules
    3. ID should always be in lower case.
-->
<!ENTITY % eURL ’URL’>
<!ENTITY % eEXPRESSION ’EXPRESSION’>
<!ENTITY % eDHTML ’DHTML’>
<!ENTITY % eDJS ’DJS’>
<!ENTITY % eSYSTEM ’SYSTEM’>

<!ENTITY % ruleSetElements ’(HTMLRules | JSRules | XMLRules)?’>
<!ENTITY % htmlElements ’(Form | Applet | Attribute)*’>
<!ENTITY % jsElements ’(Variable | Function)*’>
<!ENTITY % xmlElements ’(Attribute | TagText)*’>

<!ELEMENT RuleSet (%ruleSetElements;,%ruleSetElements;,%ruleSetElements;)>
<!ATTLIST RuleSet
    id ID #REQUIRED
    extends CDATA "none"
>

<!-- Rules for identifying rules in HTML content -->
<!ELEMENT HTMLRules (%htmlElements;)>
<!ELEMENT Form EMPTY>
<!ATTLIST Form
    name CDATA #REQUIRED
    field CDATA #REQUIRED
    valuePatterns CDATA ""
    source CDATA "*"
>

<!ELEMENT Applet EMPTY>
<!ATTLIST Applet
    code CDATA #REQUIRED
    param CDATA "*"
    valuePatterns CDATA ""
    source CDATA "*"
>

<!-- Rules for identifying rules in JS content -->
<!ELEMENT JSRules (%jsElements;)>
<!ELEMENT Variable EMPTY>
<!ATTLIST Variable
    name CDATA #REQUIRED
    type (%eURL; | %eEXPRESSION; | %eDHTML; | %eDJS; | %eSYSTEM;) "EXPRESSION"
    source CDATA "*"
>

<!ELEMENT Function EMPTY>
<!ATTLIST Function
    name CDATA #REQUIRED
    paramPatterns CDATA #REQUIRED
    type (%eURL; | %eEXPRESSION; | %eDHTML; | %eDJS;) "EXPRESSION"
    source CDATA "*"
>

<!-- Rules for identifying rules in XML content -->
<!ELEMENT XMLRules (%xmlElements;)>
<!ELEMENT TagText EMPTY>
<!ATTLIST TagText
    tag CDATA #REQUIRED
    attributePatterns CDATA ""
    source CDATA "*"
>

<!ELEMENT Attribute EMPTY>
<!ATTLIST Attribute
    name CDATA #REQUIRED
    tag CDATA "*"
    valuePatterns CDATA ""
    type (%eURL; | %eDHTML; | %eDJS; ) "URL"
    source CDATA "*"
>

You can use * as a part of rule value except that mandatory attribute values cannot be just *. Such rules are ignored, but the message is logged in the RuleSetInfo log file. For information on this log file, see Debug File Names.

Sample XML DTD

This section contains a sample rule set. The “Case Study,” on page 140 is used to illustrate how these rules are interpreted by Rewriter.

<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
Rules for integrating a mail client with the gateway.
-->
<!DOCTYPE RuleSet SYSTEM "jar://rewriter.jar/resources/RuleSet.dtd">
<RuleSet type="GROUPED" id="owa">
<HTMLRules>
<Attribute name="action" />
<Attribute name="background" />
<Attribute name="codebase" />
<Attribute name="href" />
<Attribute name="src" />
<Attribute name="lowsrc" />
<Attribute name="imagePath" />
<Attribute name="viewClass" />
<Attribute name="emptyURL" />
<Attribute name="draftsURL" />
<Attribute name="folderURL" />
<Attribute name="prevMonthImage" />
<Attribute name="nextMonthImage" />
<Attribute name="style" />
<Attribute name="content" tag="meta" />
</HTMLRules>
<JSRules>
<!-- Rules for Rewriting JavaScript variables in URLs -->
<Variable name="URL"> _fr.location </Variable>
<Variable name="URL"> g_szUserBase </Variable>
<Variable name="URL"> g_szPublicFolderUrl </Variable>
<Variable name="URL"> g_szExWebDir </Variable>
<Variable name="URL"> g_szViewClassURL </Variable>
<Variable name="URL"> g_szVirtualRoot </Variable>
<Variable name="URL"> g_szBaseURL </Variable>
<Variable name="URL"> g_szURL </Variable>
<Function name="EXPRESSION" name="NavigateTo" paramPatterns="y"/>
</JSRules>
<XMLRules>
<Attribute name="xmlns"/>
<Attribute name="href" tag="a"/>
<TagText tag="baseroot" />
<TagText tag="prop2" />
<TagText tag="prop1" />
<TagText tag="img" />
<TagText tag="xsl:attribute"
attributePatterns="name=src" />
</XMLRules>
</RuleSet>

Procedure to Write Rules

The general procedure to write rules is:

• Identify the directories that contain the HTML pages whose content needs to be rewritten.

• In these directories, identify the pages that need to be rewritten.

• Identify the URLs that need to be rewritten on each page. An easy way identify most of the URLs is to search for "http" and "/".

• Identify the content type of the URL: HTML, JavaScript or XML.

• Write the rule required to rewrite each of these URLs by editing the required ruleset in the Rewriter service under Portal Server Configuration in the Access Manager administration console.

• Combine all the rules into a ruleset for that domain.

Ruleset Guidelines

When creating a ruleset, keep the following in mind:

• The order of precedence for specific hosts is based on the longest URI match. For example for the following rulesets

  mail1.central.abc.com|iplanet_mail_ruleset
  *.sfbay.abc.com|sfbay_ruleset
  *.abc.com|generic_ruleset

  sfbay_ruleset is used as it has the longest match.

• The rules in the ruleset are applied in order to each statement in the page until a rule matches a particular statement.

  While writing the rules, keep in mind the order of the rules. Rules are applied to the statements in a page, in the order in which they occur in the ruleset. If you have specific rules, and general rules that contain a "*", define the specific rules first, then the general rules. Otherwise, the general rule is applied to all statements, even before the specific rule is encountered.

• All rules need to be enclosed within the <RuleSet> </RuleSet> tags.

• Include all rules that need to rewrite HTML content in the <HTMLRules> </HTMLRules> section of the ruleset.

• Include all rules that need to rewrite JavaScript content in the <JSRules> </JSRules> section of the ruleset.

• Include all rules that need to rewrite XML content in the <XMLRules> </XMLRules> section of the ruleset.

• In your intranet pages, identify the URLs that need to be rewritten, and include the required rules in the appropriate sections (HTML, JSRules, or XMLRules) of the ruleset.

• Assign the ruleset to the required domain.

• Restart the Gateway to affect any changes:

  gateway-install-root/SUNWportal/bin/gateway -n gateway-profile-name start

Defining the RuleSet Root Element

The ruleset root element has two attributes:

• RuleSetName, for example, default_ruleset. This name is referenced in RuleSet to URI mapping.

• Extends. This attribute refers to the inheritance feature of rulesets. The value points to the ruleset from which you would like to derive a ruleset.

  Use the value none to signify that this new, independent ruleset does not depend on any other ruleset, or specify the RuleSetName to signify that your ruleset depends on another ruleset.

Using the Recursive Feature

Rewriter uses the recursive feature to search to the end of the matched string pattern for the same pattern.

For example, when Rewriter parses the following string:

<a href="src=abc.jpg,src=bcd.jpg,src=xyz.jpg>

the rule

<Attribute name="href" valuePatterns="*src=**"/>

rewrites only the first occurrence of the pattern, which would look like this:

<a href="src=http://jane.sun.com/abc.jpg>

If you use the recursive option

<Attribute name="href" valuePatterns="REC:*src=**"/>;

Rewriter searches to the end of the matched string pattern for the same pattern, so the output would be:

<a href="src=http://jane.sun.com/abc.jpg,src=http://jane.sun.com/bcd.jpg,src=http://jane.sun.com/xyz.jpg>