Search in ILIAS

In ILIAS it is possible to search all objects created in ILIAS by means of a metadata-based or full-text search for specific keywords. Several properties of the search function are available for selection in the administration.


Settings

Define search settings

Click Administration in the main header and open the Search dialog.

The properties of the search function can be managed here:

  • Selection between direct or indexed searchNote: This mainly involves the decision as to whether the search should be more precise (direct) or still work quickly even on large installations (indexed): The indexed search uses an index to search through large amounts of data.
  • Use of Lucene (see Lucene search section)Note: The activation of Lucene is strongly recommended for performance reasons.
  • Scope of the auto-complete list (see chapter Configuring the auto-complete list)
  • Using the advanced search (see chapter Configuring the advanced search)
  • Linking several search terms with the logical operator AND or OR
  • A restriction of the search by type can be offered: Since version 4.4, the type filter also allows you to search not only for specific repository objects of the type File, but also for specific file types (PDF, Word, Excel, PowerPoint, images).

In the Advanced Search tab of the ILIAS search function, users can specify other metadata from the standard "Learning Object Metadata" as search criteria in addition to titles, descriptions and keywords, e.g. ...

  • Life cycle (draft, final version, etc.)
  • Copyright and other restrictions
  • Institutional context (school, vocational training, etc.).

The availability of metadata types in the advanced search can also be defined in the search settings in the administration. Extended metadata is not automatically provided by ILIAS, but must also be actively used by the authors of the learning material. 

Note: Extended metadata (see also the section on managing extended metadata) also appears in the list of data types that can be released for the extended search, provided that such extended metadata records and fields have already been created.

Configure auto-complete list

You can search for ILIAS accounts at various points in the system, e.g. courses and groups in ILIAS have a direct search for members.ILIAS offers the completion options matching the character combination entered in all these search options as soon as more than two characters have been entered. This function is a so-called "auto-complete list". The maximum number of entries in such an auto-complete list can also be defined in the search settings in the administration.

In the Advanced Search tab of the ILIAS search function, users can specify other metadata from the standard "Learning Object Metadata" as search criteria in addition to titles, descriptions and keywords, e.g. ...

  • Life cycle (draft, final version, etc.)
  • Copyright and other restrictions
  • Institutional context (school, vocational training, etc.).

Extended metadata is not automatically provided by ILIAS, but must also be actively used by the authors of the learning material.

The availability of metadata types in the advanced search can also be defined in the search settings in the administration.

Note: Extended metadata (see also the section on managing extended metadata) also appears in the list of data types that can be released for the extended search, provided that such extended metadata records and fields have already been created.


Lucene

Lucene search in ILIAS

By default, only objects that have been created in ILIAS, such as ILIAS learning modules, can be searched with the ILIAS full-text search. ILIAS also offers the option of using a Lucene server:<br/>Lucene is a free software project that creates search software. [...] The main component of the project - Lucene Java - is a free Java library for creating and searching text indexes (information retrieval system). They can be used to implement full-text searches for any text content. (from: http://de.wikipedia.org/wiki/Lucene, date 02.12.2009)<br/>When using Lucene in ILIAS, it is also possible to include HTML learning modules and documents in the search.

Please note, however, that Lucene is not available by default; a Lucene RPC server must first be installed on your ILIAS server.
You can find instructions for this at http://www.ilias.de/docu/goto.php?target=pg_8239_367&client_id=docu.

To be able to use the Lucene search, you must also create a new Lucene index for the first time. To do this, enter the following command in the shell:<br/>java -jar ilServer.jar <PATH_TO_SERVER_INI> createIndex <CLIENT> & <CLIENT_INFO><br/>The latter is a combination of client ID and installation ID (e.g. ILIAS4_4000).

Finally, the Lucene Index must also be updated on an ongoing basis. This can be done automatically in ILIAS by a so-called "cron job" (see also chapter Activating cron jobs).
 
The last update of the index is also indicated in the "Lucene" tab of the search settings.
 
An existing index can also be updated manually using the following command in the shell: java -jar ilServer.jar <PATH_TO_SERVER_INI> updateIndex <CLIENT> & Please note that these services must also be restarted when the server is restarted.

Lucene search: Special input options

If the so-called "Lucene search" is used in your ILIAS installation, there are further input options that you can use in the search: a search query is divided into expressions and operators. Expressions are individual expressions, phrases and sub-queries:

  • A single term is a single word, e.g. ILIAS or e-learning.
  • A phrase is a group of individual expressions surrounded by double quotation marks, e.g. "Documentation search".
  • A subquery is a query that is surrounded by brackets, e.g. : (ILIAS LMS)

Boolean operators:Several expressions can be combined with the so-called Boolean operators (AND, OR, AND NOT) to form more complex queries. Phrases and sub-queries can also be included. You can also use "+" instead of AND and "-" instead of AND NOT:

  • x AND y: all entered expressions
  • x OR y: one of the entered expressions
  • x OR (y AND z): either the expression x or the combination of y and z
  • x AND (y OR z): Combination of the expression x and either y or z
  • x AND "y z": Combination of the expression x and the phrase "y z", i.e. only locations where y and z appear in immediate succession
  • x AND NOT y: only locations of x that do not also contain y

Index fields:The Lucene search in ILIAS allows you to search through certain properties of objects ("index fields"). For example, you can search for property owners or property types:

  • Field: title 
    • z. e.g. title: ILIAS - (All ILIAS objects whose title contains the word ILIAS)
  • Field: description
    • z. e.g. description: "E-Learning" - (All ILIAS objects that contain the term "One category" in the description field)
  • Field: content 
    • z. e.g. content: (ILIAS or LMS) - (All materials whose content (page content, glossary terms, forum articles...) contain the term "ILIAS" or "LMS")
  • Field: type: crs
    • z. e.g. type: crs - (All ILIAS courses)
  • Field: owner 
    • z. e.g. owner: d.dozent - All ILIAS objects created by the user "d.dozent".
  • Field: tag
    • z. e.g. tag: navigation - All ILIAS objects tagged with the word "navigation".

Wildcards: The Lucene search in ILIAS also allows single-character and multi-character searches with wildcards in individual expressions (but not within phrases).

  • To perform a single character wildcard search, the "?" character can be used.the single character wildcard search searches for words that match the term, replacing the "?" with any single character.
  • To perform a multi-character wildcard search, the "*" character can be used.the multi-character wildcard search searches for words that match the term, replacing the "*" with 0 or more characters.

Examples:

  • Te?t - finds "Test" and "Text"
  • tes* - finds "test", "tester", "texts"...
  • I*A? - finds ILIAS

Fuzzy search:
It is also possible to perform a "fuzzy" search, i.e. a search with error tolerance based on the so-called "Levenshtein distance".To perform a fuzzy search, the tilde character "~" must be appended to an expression.An additional optional parameter can specify the required similarity. The value must be between 0 and 1. With a value closer to 1, only terms with a higher probability are found.examples:

  • House~: finds "house", "mouse", "louse"
  • House~0.4: finds "house", "mouse", "louse", "rabbit", "skin"

Approximate search:ILIAS supports finding words from a phrase that are a specified distance away from words in a string. To perform an approximate search, the tilde symbol must be used at the end of the phrase:

  • "ILIAS Documentation"~2: finds "ILIAS 3 Documentation"

Increasing the relevance of query components:To increase the relevance of an expression, the caret character ("^") can be used in combination with a boost factor. The higher the selected factor, the greater its influence on the relevance of the search result:

  • LIAS^3 documentation: increases the relevance of search results containing the term "ILIAS" by a factor of 3
  • ILIAS type:frm^0.2: reduces the relevance of hits in ILIAS forums by a factor of 5

Once the Lucene server has been installed and its index created, the behavior of the Lucene search can be configured in the "Lucene" tab of the search settings.

The following details can be set:

  • Since version 4.4, you can release the search for users ("Person search" option): Users can then search for other users. However, if a user has not shared their profile, only their user name, first name and surname will appear. Otherwise, by clicking on the picture, his/her profile can be called up, which contains all the information that has been explicitly released by the user.
  • Since version 4.4, you can also activate a "file type filter" for the Lucene search, so that you can filter not only by ILIAS object types, but even within file objects by those that have a specific file type (possible for PDF, Word, Excel, PowerPoint and images).
  • A third new feature in version 4.4 is the option of allowing placeholders at the beginning of a search term.
  • Search results can be sorted according to their relevance.
    If the "Show relevance" option is activated, the relevance of the respective search result is displayed in percentages as additional information for all hits.
    • Maximum number of sub-objects that are displayed
    • maximum number of text sections that should be output to highlight the search hits
    • their maximum length (up to 1000 characters)
  • Since version 4.4, you also have the option of displaying the relevance for sub-objects.
  • Note: Finally, the Lucene Index must also be updated on an ongoing basis. This can be done automatically in ILIAS by a so-called cron job (see also chapter Activating and configuring cron jobs). The last update of the index is also indicated in the "Lucene" tab of the search settings. An existing index can also be updated manually using the following command in the shell:java -jar ilServer.jar <PATH_TO_SERVER_INI> updateIndex <CLIENT> &Note that these services must also be restarted when the server is restarted.