"Narrow your search" widget

Date	2012/09/11
Contact(s)	François Prunayre
Last edited	2012/09/11
Status	Ongoing
Assigned to release	2.9.x
Resources	Resource available

Overview

This proposal aims to provide a « Narrow your search » module aka as faceted search (​http://en.wikipedia.org/wiki/Faceted_search). This module allows aggregation based on criteria (e.g. keywords, organization, dates, ...) with frequency for the current search. Output view could be a list (with link to add a specific criteria to the search) and optionnaly a tagcloud view (​http://en.wikipedia.org/wiki/Tag_cloud).

On the client side, user interacts with facets using :

• the facets summary used to select new filter
• the facet breadcrumb which indicates which filter has been applied

and allows user to remove a filter.

Those 2 components are created and interact with search form and search results widgets.

A first implementation has been made on geocat.ch using the internal summary module in 2008. This proposal is using Lucene faceting module to compute the summary.

Proposal Type

• Type: GUI Change, LuceneSearcher
• App: GeoNetwork
• Module: Search Interface

Links

• Documents:
  • example ​http://www.geocatalogue.fr/, ​http://www.geocat.ch
• Email discussions:
• Other wiki discussions:

Voting History

• Vote proposed by X on Y, result was +/-n (m non-voting members).

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Motivations

• Improve user search experience : facets help user to quickly refine search
• Better performance : Lucene facet module using its own taxonomy index is faster than computing summary.
• New way of presenting information : facet could be use to provide catalog indicators using charts (​http://www.youtube.com/watch?v=ISEOKOq6t2Q&feature=plcp)

Proposal

Facet configuration

The facet configuration define which field in the index to use to compute the summary. The configuration is stored in WEB-INF/config-summary.xml. For each facet configure the following properties:

• name: the name of the facet (ie. the tag name in the XML response)
• plural: the plural for the name (ie. the parent tag of each facet values)
• indexKey: the name of the field in the index
• sortBy: the ordering for the facet. Defaults is by count.
• sortOrder: asc or desc. Defaults is descendant.
• max: the number of values to be returned for the facet. Defaults is 10.

Configuration example:

<item name="keyword" plural="keywords" indexKey="keyword"/>

<item name="createDateYear" plural="createDateYears" indexKey="createDateYear"
				sortBy="value" sortOrder="asc" max="40"/>

Facet response

Current implementation produce (see xml.search service) :

<response>
  <summary count="4797" type="local">
    <keywords>
<keyword count="1280" name="soil types"/>
<keyword count="1003" name="geology"/>
<keyword count="958" name="soils"/>
<keyword count="894" name="soil classification"/>
<keyword count="695" name="land use"/>
<keyword count="609" name="topography"/>
<keyword count="595" name="land suitability"/>
<keyword count="550" name="land"/>
<keyword count="508" name="physiography"/>
<keyword count="507" name="crops"/>
</keywords>
  <categories>
<category count="165" name="datasets"/>
<category count="2" name="interactiveresources"/>
<category count="150" name="maps"/>
</categories>
  <sources>
<source count="4350" name="d5a5b43b-6e52-4ec6-94af-f95c6e4dac24"/>
<source count="447" name="34475e9d-9b9e-48d1-b75c-08701c3a8f93"/>
</sources>
</summary>
<metadata>

Performance analysis

Changes

• Lucene
  • Update to version 3.6.1
  • New dependency : lucene-facet
• LuceneSearcher.makeSummary()
• Add an option to search services to only produce the summary (like the fast option but really fast / only summary)
• Add config file to define
  • criteria : MUST be in the index
  • criteria type : String|Number|Date
  • agregation type :
    • String : count
    • Number : count|equalInterval + classe ?| quantil + classe
    • Date : count|annualy|monthly|daily
    • sort option (count|name)

Backwards Compatibility Issues

Risks

Participants

• As above