Rules for HTML Content

HTML content in web pages can be classified into attributes, JavaScript tokens, forms, and applets. Accordingly, the rules for HTML content are classified as:

• Attribute Rules for HTML Content

• JavaScript Token Rules for HTML Content

• Form Rules for HTML Content

• Applet Rules for HTML Content

Attribute Rules for HTML Content

Attribute rules identify the basic attribute tags in HTML pages to rewrite. Rewriter modifies the various occurrences of the defined tags by expanding or prefixing the existing URL. The default ruleset rewrites the following attribute tags:

• action

• background

• codebase

• code

• href

• src

• value

• imagePath

• lowsrc

• archive

The syntax for attribute rules is:

<Attribute name="name" [tag="tag" valuePatterns="patterns"]

where name specifies the attribute, tag specifies the tag to which the attribute belongs (set to * to match all tags), and patterns specifies the possible patterns to match with the attribute. The tag and valuePatterns parameters are optional.

JavaScript Token Rules for HTML Content

Web pages can contain pure JavaScript code within the JavaScript tags, or they can contain JavaScript tokens or functions. For example, a web page can contain an onClick() function that causes a jump to a different URL. In order for the page to function properly, the value of the onClick() function needs to be translated and rewritten. In most cases, the rules provided in the default ruleset are sufficient to rewrite the URLs in JavaScript tokens. The default ruleset rewrites the following JavaScript tokens:

• onAbort

• onBlur

• onChange

• onClick

• onDblClick

• onError

• onFocus

• onKeyDown

• onKeyPress

• onKeyUp

• onLoad

• onMouseDown

• onMouseMove

• onMouseOut

• onMouseOver

• onMouseUp

• onReset

• onSelect

• onSubmit

• onUnload

The syntax for JavaScript Token rules is:

<JSToken>javascript_function_name</JSToken>

where javascript_function_name is the name of the function such as onLoad or onClick.

Form Rules for HTML Content

Users can browse HTML pages that contain forms. Form elements, such as input, can take a URL as a value. The default ruleset does not rewrite any form elements. The syntax for form rules is:

<Form source="/source.html" name="form1" field="field1"> [valuePatterns="pattern"] />

where /source.html is the URL of the HTML page containing the form, form1 is the name of the form, field1 is the field of the form to be rewritten, and pattern indicates the part of the field to be rewritten. All content that follows the pattern specified is rewritten.

The valuePatterns parameter is optional.

Applet Rules for HTML Content

A single web page can contain many applets, and each applet can contain many parameters. The Rewriter rule for URLs in applets should contain pattern matching information for the following:

• source, such as filename.htm

• code, such as classname.class

• parameter name, such as servername

• parameter value, such as some_url

Rewriter matches the values specified in the rule with the content of the applet and modifies the URLs as required. This replacement is carried out at the server and not when the user is browsing the particular web page. A wildcard character (*) can also be used as part of the rule. For example, the parameter name could be *, in which case, the Rewriter does not compare the parameter name in the applet.

The default ruleset does not rewrite any applet parameters.

The syntax for applet rules is:

<Applet source="sourcehtml.jsp" code="class" param="parameter_name"
[valuePatterns="pattern"]

where /sourcehtml.jsp is the URL containing the applet, class is the name of the applet class, parameter_name is the parameter whose value needs to be rewritten, and pattern indicates the part of the field to be rewritten. All content that follows the pattern specified is rewritten. The valuePatterns parameter is optional.