7.4 - Results Format

Results Format

Custom HTML

Custom HTML Output Overview

Internationalization

XML Output

XML Output Overview

Character Encoding Conventions

Google XML Results DTD

Google XML Tag Definitions

This section covers the following topics:

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Custom HTML

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XML Output

Custom HTML

This section describes the custom HTML results.

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Custom HTML Output Overview

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Internationalization

Custom HTML Output Overview

Google Search Appliance has a built-in XSLT (eXtensible Stylesheet Language Transformation) server, and can generate custom HTML using your XSL stylesheet. Search requests that include the output parameter set to xml_no_dtd and a valid proxystylesheet parameter value are automatically processed by the XSLT server as requests for custom HTML output.

Using the XSL stylesheet specified by the proxystylesheet parameter, the XSLT server applies the transformation rules found in the XSL stylesheet to the standard Google XML results. Although this document assumes that the output generated by applying the XSL stylesheet is HTML, almost any output format can be generated by using appropriate XSL stylesheet rules. For any front end, the default XSL stylesheet can be customized or replaced by the search administrator.

To customize the XSL stylesheet used to generate custom HTML output, see XML Output to determine the XML tags that may be transformed using a customized XSL stylesheet.

Additionally, you can leverage the proxycustom parameter to pass custom XML tags to the XSLT server. Because including custom XML does not generate search results, this feature is useful for implementing additional static search pages, such as an advanced search page.

Customizations to XSLT stylesheets may result in vulnerability to cross-site scripting (XSS) attacks. Google recommends that you run XSS test after customizing an XSLT stylesheet.

Notes:

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XSL stylesheets used by the XSLT server are cached for 15 minutes. To force the XSLT server to use the latest version of an XSL stylesheet, set the proxyreload input parameter to a value of 1 in your search request.

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XSL stylesheets that include other files may not be used with the Google search engine. An XSL stylesheet that contains the following tags generates an error result:

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When you request cached results in custom HTML output, the BLOB XML tag and associated value are automatically converted to the original text before the XSL stylesheet rules are applied. When using an XSL stylesheet that customizes cache results, simply use the values of the CACHE_LEGEND_TEXT, CACHE_LEGEND_NOTFOUND and CACHE_LEGEND_HTML XML tags directly instead of applying a rule on the BLOB subtag.

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If you use input or output encodings other than latin1, see Internationalization for more details.

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More information about XSL and XSLT can be found on the W3C (http://www.w3.org/Style/XSL/) web site.

Internationalization

The Google Search Appliance handles over 20 character encoding schemes. This section discusses special considerations for the custom HTML output format with encoding schemes other than latin1.

To support all the encoding schemes supported by Google, the XSLT server follows a process to ensure that the results are returned in the correct encoding scheme. When requesting search results through the XSLT server, the server translates the results to the UTF8 encoding scheme before applying the selected XSL stylesheet. After the XSL stylesheet rules are applied to generate the results, the results are converted to the encoding scheme that is specified by the output encoding parameter, oe. The one exception to this rule is cached result pages, which get converted to the encoding scheme of the cached document after XSLT processing.

Each front end for your search appliance is associated with an underlying stylesheet. All XSL stylesheets must be in latin1 or UTF8 formats.

XML Output

The description of the XML results format contains the following sections:

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XML Output Overview

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Character Encoding Conventions

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Google XML Results DTD

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Google XML Tag Definitions

XML Output Overview

For maximum flexibility, Google provides search results in XML format. Using the Google XML results, you can use your own XML parser to customize the display for your search users. If you are using an XSL stylesheet to transform the XML results instead of developing your own XML parser, proceed to Custom HTML.

Notes:

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Element values are valid HTML and are suitable for display, unless otherwise noted in the XML tag definitions. Some values are URLs and must be HTML-encoded to be displayed.

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To remain forward-compatible, your XML parser that parses Google search results should ignore attributes or tags that are not documented. By ignoring unknown tags, your custom XML parser can continue working without modification when Google adds more features to the XML output in the future.

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For custom parameters that contain spaces, each space is replaced with “_”. You can still retrieve the unmodified value from the original_value attribute. For example:

<param name="temp" value="token_ring" original_value="token+ring" />

Character Encoding Conventions

The first line of the XML results indicates which character encoding is used. See XML Standard for information about character encoding (http://www.w3.org/TR/1998/REC-xml-19980210#charencoding).

Certain characters must be escaped when they are included as values in XML tags. These characters are documented in XML Standard (http://www.w3.org/TR/1998/REC-xml-19980210#dt-escape), and are shown in the table that follows. All other characters in the XML results are presented without modification.


Character	Escaped Form
<	either < or <
&	either & or &
>	either > or >
’	either ' or '
"	either " or "

Google XML Results DTD

Google XML results can be returned with or without a reference to the most recent DTD (Document Type Definition) describing Google’s XML format. The DTD is a guide to help search administrators and XML parsers understand the XML results output. Because Google’s XML grammar may change from time to time, do not configure your parser to use the DTD to validate the XML results.

XML parsers should not be configured to fetch the DTD every time a search request is performed. Because the DTD is updated infrequently, these fetches create unnecessary delay and bandwidth requirements.

To get results in XML output format, use one of the following parameters in the search request:

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output=xml_no_dtd (recommended), or

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output=xml

When you use the xml output format, the XML results include the line:

<!DOCTYPE GSP SYSTEM "google.dtd">

The DTD is available on the Google Search Appliance at http://<appliance_hostname>/google.dtd.

Google XML Tag Definitions

This section contains an index of Google’s XML tags.

Subtags legend:


?	zero or one instance of the subtag
*	zero or more instances of the subtag
+	one or more instances of the subtag
\|	Boolean OR

BLOB

Name	Format	Description
encoding	Text (Encoding Scheme)	The encoding scheme of the HTML data (See Internationalization for a list of common encoding values)

Attribute	Value	Format	Description
NAME	PatternScorer	Text	Used for both source biasing and collection biasing.
	DateBias	Text	Used for date biasing.
	Metadata	Text	Used for metadata biasing.
VALUE	3	Text	For a strong increase.
	2	Text (integer)	For a medium increase.
	1	Text (integer)	For a weak increase.
	0	Text (integer)	For no change.
	-3	Text (integer)	For a strong decrease.
	-2	Text (integer)	For a medium decrease.
	-1	Text (integer)	For a weak decrease.

Google Search Appliance Documentation