7 How do I use it?

7.1.1.1 Sort order for description filters

7.5.2.1 Required parameters

The <params> element has four required elements for determining the resource collection that you wish to index: <searchFile>, <recurse>, <stopwordsFile>, and <dictionaryFile>.

• searchFile (The search file (aka page) that will be the primary access point for the staticSearch. Note that this page must be at the root of the collection directory.)

The search page is a regular HTML page which forms part of your site. The only important characteristic it must have is a <div> element with id=staticSearch, whose contents will be rewritten by the staticSearch build process. See 7.6 Creating a search page.

The <searchFile> element is a relative URI (resolved, like all URIs specified in the config file, against the configuration file location) that points directly to the search page that will be the primary access point for the search. Since the search file must be at the root of the directory that you wish to index (i.e. the directory that contains all of the XHTML you want the search to index), the searchFile parameter provides the necessary information for knowing what document collection to index and where to put the output JSON. In other words, in specifying the location of your search page, you are also specifying the location of your document collection. See Creating a search page for more information on how to configure this file.

Note that all output files will be in a directory that is a sibling to the search page. For instance, in a document collection that looks something like:

• myProject
  • novel.html
  • poem.html
  • shortstory.html
  • search.html

The collection of Javascript and JSON files will be in a directory like so:

• myProject
  • novel.html
  • poem.html
  • shortstory.html
  • search.html
  • staticSearch

• recurse (Whether to recurse into subdirectories of the collection directory or not.)

We also require the <recurse> element in the case where the document collection may be nested (as is common with static sites generated from Jekyll or Wordpress). The <recurse> element is a boolean (true or false) that determines whether or not to recurse into the subdirectories of the collection and index those files.

In order to support stemming and phrasal search effectively, it is important to specify a <stopwordsFile> (a file containing words that will be ignored at index time) and a <dictionaryFile> (also used for indexing). Default files for English and French are supplied in the xsl folder, but you will probably want to create or customize the stopword list for your own project. You may also supply empty text files for these parameters if for example you donʼt want to use a stoplist at all.

• stopwordsFile (The relative path (from the config file) to a text file containing a list of stopwords (words to be ignored when indexing). )

A stopword is a word that will not be indexed, because it is too common (the, a, you and so on). There are common stopwords files for most languages available on the Web, but it is probably a good idea to take one of these and customize it for your project, since there will be words in the website which are so common that it makes no sense to index them, but they are not ordinary stopwords. For example, in a Website dedicated to the work of John Keats, the name keats should probably be added to the stopwords file, since almost every page will include it, and searching for it will be pointless. The project has a built-in set of common stopwords for English, which you'll find in xsl/english_stopwords.txt. One way to find appropriate stopwords for your site is to generate your index, then search for the largest JSON index files that are generated, to see if they might be too common to be useful as search terms. You can also use the Word Frequency table in the generated staticSearch report (see 7.9 Generated report).

• dictionaryFile (The relative path (from the config file) to a dictionary file (one word per line) which will be used to check tokens when indexing.)

The indexing process checks each word as it builds the index, and keeps a record of all words which are not found in the configured dictionary. Though this does not have any direct effect in the indexing process, all words not found in the dictionary are listed in the staticSearch report (see 7.9 Generated report). This can be very useful: all words listed are either foreign (not part of the language of the dictionary) or perhaps misspelled (in which case they may not be correctly stemmed and index, and should be corrected). There is a default dictionary in xsl/english_words.txt which you might copy and adapt if you're working in English; lots of dictionaries for other languages are available on the Web.

7.5.2.2 Optional parameters

The following parameters are optional, but most projects will want to specify some of them:

• versionFile (The relative path to a text file containing a single version identifier (such as 1.5, 123456, or 06ad419). This will be used to create unique filenames for JSON resources, so that the browser will not use cached versions of older index files.)

<versionFile> enables you to specify the path to a plain-text file containing a simple version number for the project. This might take the form of a software-release-style version number such as 1.5, or it might be a Subversion revision number or a Git commit hash. It should not contain any spaces or punctuation. If you provide a version file, the version string will be used as part of the filenames for all the JSON resources created for the search. This is useful because it allows the browser to cache such resources when users repeatedly visit the search page, but if the project is rebuilt with a new version, those cached files will not be used because the new version will have different filenames. The path specified is relative to the location of the configuration file (or absolute, if you wish). If you do not provide a version file, a random identifier will be generated instead.

• phrasalSearch (Whether or not to support phrasal searches. If this is true, then the maxContexts setting will be ignored, because all contexts are required to properly support phrasal search.)

Phrasal search functionality enables your users to search for specific phrases by surrounding them with quotation marks ("), as in many search engines. In order to support this kind of search, <createContexts> must also be set to true as we store contexts for all hits for each token in each document. Turning this on will make the index larger, because all contexts must be stored, but once the index is built, it has very little impact on the speed of searches, so we recommend turning this on. The default value is true. However, if your site is very large and your user base is unlikely to use phrasal searching, it may not be worth the additional build time and increased index size.

• stemmerFolder (The name of a folder inside the staticSearch /stemmers/ folder, in which the JavaScript and XSLT implementations of stemmers can be found. If left blank, then the staticSearch default English stemmer (en) will be used.)

The staticSearch project currently has only two real stemmers: an implementation of the Porter 2 algorithm for modern English, and an implementation of the French Snowball stemmer. These appear in the /stemmers/en/ and /stemmers/fr/ folders. The default value for this parameter is en; to use the French stemmer, use fr. We will be adding more stemmers as the project develops. However, if your document collection is not English or French, you have a couple of options, one hard and one easy.

• Hard option: implement your own stemmers. You will need to write two implementations of the stemmer algorithm, one in XSLT (which must be named ssStemmer.xsl) and one in JavaScript (ssStemmer.js), and confirm that they both generate the same results. The XSLT stemmer is used in the generation of the index files at build time, and the JavaScript version is used to stem the user's input in the search page. You can look at the existing implementations in the /stemmers/en/ folder to see how the stemmers need to be constructed. Place your stemmers in a folder called /stemmers/[yourlang]/, and specify yourlang in the configuration file.
• Easy option: Use the identity stemmer (which is equivalent to turning off stemming completely), and make sure wildcard searching is turned on. Then your users can search using wildcards instead of having their search terms automatically stemmed. To do this, specify the value identity in your configuration file.

Another alternative is the stripDiacritics stemmer. Like the identity stemmer, this is not really a stemmer at all; what it does is to strip out all combining diacritics from tokens. This is a useful approach if you document collection contains texts with accents and diacritics, but your users may be unfamiliar with the use of diacritics and will want to search just with plain unaccented characters. For example, if a text contains the word élève, but you would like searchers to be able to find the word simply by typing the ascii string eleve, then this is a good option. Combined with wildcards, it can provide a very flexible and user-friendly search engine in the absence of a sophisticated stemmer, or for cases where there are mixed languages so a single stemmer will not do. To use this option, specify the value stripDiacritics in your configuration file.

• scoringAlgorithm (The scoring algorithm to use for ranking keyword results. Default is "raw" (i.e. weighted counts))

<scoringAlgorithm> is an optional element that specifies which scoring algorithm to use when calculating the score of a term and thus the order in which the results from a search are sorted. There are currently two options:

• raw: This is the default option (and so does not need to be set explicitly). The raw score is simply the sum of all instances of a term (optionally multipled by a configured weight via the <rule>/weight configuration) in a document. This will usually provide good results for most document collections.
• tf-idf: The tf-idf algorithm (term frequency-inverse document frequency) computes the mathematical relevance of a term within a document relative to the rest of the document collection. The staticSearch implementation of tf-idf basically follows the textbook definition of tf-idf: tf-idf = ($instancesOfTerm / $totalTermsInDoc) * log( $allDocumentsCount / $docsWithThisTermCount ) This is fairly crude compared to other search engines, like Lucene, but it may provide useful results for document collections of varying lengths or in instances where the raw score may be insufficient or misleading. There are a number of resources on tf-idf scoring, including: Wikipedia and Christopher D. Manning, Prabhakar Raghavan and Hinrich Schütze, Introduction to Information Retrieval, Cambridge University Press. 2008.

• createContexts (Whether to include keyword-in-context extracts in the index.)

<createContexts> is a boolean parameter that specifies whether you want the indexer to store keyword-in-context extracts for each of the hits in a document. This increases the size of the index, but of course it makes for much more user-friendly search results; instead of seeing just a score for each document found, the user will see a series of short text strings with the search keyword(s) highlighted. Note that contexts are necessary for phrasal searching or wildcard searching.

• minWordLength (The minimum length of a term to be indexed. Default is 3 characters.)

<minWordLength> specifies the minimum length in characters of a sequence of text that will be considered to be a word worth indexing. The default is 3, on the basis that in most European languages, words of one or two letters are typically not worth indexing, being articles, prepositions and so on. If you set this to a lower limit for reasons specific to your project, you should ensure that your stopword list excludes any very common words that would otherwise make the indexing process lengthy and increase the index size.

• maxKwicsToHarvest (This controls the maximum number of keyword-in-context extracts that will be stored for each term in a document.)

<maxKwicsToHarvest> controls the number of keyword-in-context extracts that will be harvested from the data for each term in a document. For example, if a user searches for the word ‘elephant’, and it occurs 27 times in a document, but the <maxKwicsToHarvest> value is set to 5, then only the first five (sorted in document order) of these keyword-in-context strings will be stored in the index. (This does not affect the score of the document in the search results, of course.) If you set this to a low number, the size of the JSON files will be constrained, but of course the user will only be able to see the KWICs that have been harvested in their search results. If <phrasalSearch> is set to true, the <maxKwicsToHarvest> setting is ignored, because phrasal searches will only work properly if all contexts are stored.

• maxKwicsToShow (This controls the maximum number of keyword-in-context extracts that will be shown in the search page for each hit document returned.)

A user may search for multiple common words, so hundreds of hits could be found in a single document. If the keyword-in-context strings for all these hits are shown on the results page, it would be too long and too difficult to navigate. This setting controls how many of those hits you want to show for each document in the result set.

• totalKwicLength (If createContexts is set to true, then this parameter controls the length (in words) of the harvested keyword-in-context string.)

Obviously, the longer the keyword-in-context strings are, the larger the individual index files will be, but the more useful the KWICs will be for users looking at the search results. Note that the phrasal searching relies on the KWICs and thus longer KWICs allow for longer phrasal searches.

• kwicTruncateString (The string that will be used to signal ellipsis at the beginning and end of a keyword-in-context extract. Conventionally three periods, or an ellipsis character (which is the default value).)

The only reason you might need to specify a value for this parameter is if the language of your search page conventionally uses a different ellipsis character. Japanese, for example, uses the 3-dot-leader character.

• linkToFragmentId (Whether to link keyword-in-context extracts to the nearest id in the document. Default is true.)

<linkToFragmentId> is a boolean parameter that specifies whether you want the search engine to link each keyword-in-context extract with the closest element that has an id. If the element has an ancestor with an id, then the indexer will associate that keyword-in-context extract with that id; if there are no suitable ancestor elements that have an id, then the extract is associated with first preceding element with an id. We strongly recommend that you ensure your target documents have id attributes for any significant divisions so that this parameter can be used effectively. With lots of ids throughout your documents, and this parameter turned on, each keyword-in-context in the results page will be linked directly to the section of the document in which the hit appears, making the search results much more useful.

• scrollToTextFragment (WARNING: Experimental technology. This turns on a feature currently only supported by a subset of browsers, enabling links from keyword-in-context results directly to the specific text string in the target document.)

Google has proposed a browser feature called Text Fragments, which would support a special kind of link that targets a specific string of text inside a page. When clicking on such a link, the browser would scroll to, and then highlight, the target text. This has been implemented in Chrome-based browsers (Chrome, Chromium and Edge) at the time of writing, but other browser producers are sceptical with regard to the specification and worried about possible security implications. The specification is subject to radical change. <scrollToTextFragment> is a boolean parameter that specifies whether you want to turn on this feature for browsers that support it. It depends on the availability of keyword-in-context strings, so <createContexts> must also be turned on to make it work. The feature is automatically suppressed for browsers which do not support it. We recommend only using this feature on sites which are in steady development, so that if necessary it can be turned off, our the staticSearch implementation can be updated to take account of changes. For sites intended to remain unchanged or archived for any length of time, this feature should be left turned off. It is off by default. A more reliable alternative is probably to use JavaScript to highlight hits on the target page.

• resultsPerPage (The maximum number of document results to be displayed per page. All results are displayed by default; setting resultsPerPage to a positive integer creates a Show More/Show All widget at the bottom of the batch of results.)

For most sites, where the number of results is likely to be in the low thousands, it's perfectly practical to show all the results at once, because the staticSearch processor is so fast. However, if you have tens of thousands of documents, and it's possible that users will do (for example) filter-only searches that retrieve a large proportion of them, you can constrain the number of results which are shown initially using this setting. All the results are still generated and output to the page, but since most of them are hidden until the ‘Show More’ or ‘Show All’ button is clicked, the browser will render them much more quickly.

• verbose (Turns on more detailed reporting during the indexing process.)

The staticSearch build process can be lengthy, and if something goes wrong it can be difficult to figure out where the problem was. If you're having build problems, turn on verbose messages in the configuration file to help with debugging, and you'll see a lot more output at the command line.

• indentJSON (Whether or not to indent code in the JSON index files. Indenting increases the file size, but it can be useful if you need to read the files for debugging purposes.)

Normally, the JSON index files will only be processed by JavaScript, so there is no need to indent them, but if you are debugging or investigating how the code works, you may find it useful to generate them in a more human-readable layout.

• outputFolder (The name of the output folder into which the index data and JavaScript will be placed in the site search. This should conform with the XML Name specification.)

When the staticSearch build process creates its output, many files need to be added to the website for which an index is being created. For convenience, all of these files are stored in a single folder. This element is used to specify the name of that folder. The default is staticSearch, but if you would prefer something else, you can specify it here. You may also use this element if you are defining two different searches within the same site, so that their files are kept in different locations.