Package lumis.search

Provides classes for implementing search services integrated to Lumis Portal.

See: Description

Interface Summary

Interface	Description
IAttributeSetReader	Provides a common way to read attribute values, which consist in information exchanged between the portal and the search engines.

Class Summary

Class	Description
CriteriaUtil	Evaluates if an attribute set matches an specified criteria.
Indexer	Stores searcheable data in a search engine.
IndexerFactory	Creates instances of concrete Indexer implementations.
Processor	Represents an element that interacts to an index and provides searching services, such as indexing and searching, according to configuration in Search Config File (SearchConfig.xml).
SearchAttributes	Set of attributes aggregated to a SearchQuery, a SearchHit or a SearchResults.
SearchContent	Unit of searchable information, containing one or more SearchContentField objects.
SearchContentAttachment	Attachment to a SearchContent object.
SearchContentField	Field of a SearchContent object.
SearchContext	Context for search infrastructure, that gives access to search configuration.
Searcher	Searchs for data in a search engine.
SearcherFactory	Creates instances of concrete Searcher implementations.
SearchHit	An item of a SearchResults object.
SearchQuery	Represents search criteria used to find matching information by a search engine.
SearchResults	Represents a collection of hits returned by a query execution.
SearchStringResource	Strings resource for search infra-structure.
SmartTagUtil	Utility class that replaces EL field variables by related field values, to be used in search configuration in searchconfig.xml file.

Exception Summary

Exception	Description
SearchException	Search infra-structure related exception.

Package lumis.search Description

Provides classes for implementing search services integrated to Lumis Portal.

1. Introduction

This package contains classes that can be used to implement ways to portal services index their data, in order to search for this data later, based on user-entered criteria. In other words, these classes compose an extensible search engine architecture, to be used by portal projects based on Lumis Portal.

Lumis Portal comes with an implementation of search engine based on Apache Lucene. It's the default search engine used. Portals based on Lumis Portal have a configuration that allows the use of one or more compatible search engines to index and search for services data.

When you have data that needs to be searchable, it has to be indexed first. The indexing process is done by an Indexer implementation. Then, later, when, for example, an user requests a data search, a search is executed by a Searcher implementation.

2. Main Concepts and Classes

2.1. Searchable Information

A searchable information is any textual information that can be stored by a search engine and later be found by some textual criteria such as keywords and text fragments.

Portal services can deal with several kinds of information, such as news, articles, images and files. Any kind of information can be considered "searchable" once it has some textual portion. For example, a news is a typical textual content and obviously searchable. In other hand, an image can considered "searchable" only if it has some aggregated textual information, such as image authoring or description. A file will be searchable only if its format allows text extraction.

Once the textual searchable information was given or extracted from original information, it can be indexed and searched using the infra-structure present in this package.

A searchable information is encapsulated in a SearchContent object.

2.1.1. Fields

A searchable information is composed by one or more fields, each of them having a name and one or more string values.

A field is represented by a SearchContentField object.

There are five predefined field types:

• Identifier: identifies the information;
• Title: title of the information;
• Subtitle: subtitle of the information;
• URL: URL to the information details;
• Text: searchable text of the information.

2.2. Search Engine

A search engine is a subsystem that provides indexing and searching functionality to the portal infra-structure.

Basically, a search engine is a set of implementations for Indexer and Searcher implementations that has a configuration section in the configuration file.

The default search engine that comes with Lumis Portal is an implementation based on Apache Lucene, a popular Information Retrieval framework that stores searchable information on indexes in the file system.

Custom search engines can be implemented to integrate a portal solution to other search engines and IR frameworks.

2.3. Indexing

Indexing is the action of storing a searchable information, in a way that allows to find this information using text search criterias, such as keywords or information fragments.

A typical data indexing cycle is composed by the following steps:

• A search engine is selected, based on portal configuration;
• A SearchContent object, that contains one or more SearchContentField objects, is populated with the data;
• An implementation of Indexer, related to the selected search engine, is instantiated;
• The SearchContent object is indexed using Indexer.addSearchContent(SearchContent).

Some search engines can pre-process the information before it is stored, to perform some common actions, like case normalization, common words cleaning etc.

A search engine provides indexing functionality through an implementation of the Indexer class, that receives the searchable information to be indexed in a SearchContent object, which has a collection of SearchContentField objects.

2.4. Searching

Searching is the action of find an information based on a certain criteria, usually a portion of the original information. This portion can be a keyword given by the user or any fragment of information that can be used to match one or more previosly indexed informations.

A typical search cycle consists in the following steps:

• A search engine is selected, based on portal configuration;
• A SearchQuery object is populated with the user-entered search criteria;
• An implementation of Searcher, related to the selected search engine, is instantiated;
• The data is searched using the Searcher.search(SearchQuery) method;
• The search results are returned in a SearchResults object, that contains one SearchHit object for each result that matches the criteria.

Some search engines, like the default search engine, provide advanced features that can be used in search criterias, such as wildcards and boolean operators.

A search engine provides searching functionality through an implementation of the Searcher class, that receives the search criteria in a SearchQuery object. The search results returns from the search engine in a SearchResults object, which has one SearchHit object for each searchable information that matches the given search criteria.

3. The Search Configuration File

The Lumis Portal's search infra-structure can be configured using the configuration file searchconfig.xml, that can be found in the lumisdata/config directory.

Since:

4.0.4

Version:

$Revision: 10348 $ $Date: 2009-04-13 17:31:28 -0300 (Mon, 13 Apr 2009) $