redis-dictionary

Implements basic word lookup mechanism using redis as the indexing engine. This implementation has been inspired by the following article http://antirez.com/post/autocomplete-with-redis.html

Summary

This library provides a mechanism to index and lookup data based on keywords extracted from the data. At the heart of this library are word dictionaries which are used to index the data based on keywords extracted from the data. These dictionaries can then be used to lookup data based on related keywords. Currently implemented word dictionaries are:

• Word completion dictionary : based on partial or full keywords it provides a list of keywords (complete) stored against indexed data. For instance if keyword kitty was stored then it can be lookup using partial word i.e. ki, kit, etc. (starts with partern is used)
• Metaphone dictionary (sounds like) : indexes words by their Metaphone value. This allows mistyped words to be looked up easily i.e. if cat was indexed, it can be lookup by kat, kit, etc. This uses apache codec library which provides Metaphone calculation.

On top of the word dictionaries, the library provides a lightweight search service implementation RedisKeywordDataRepository which implements interface SearchableKeywordDataRepository. This implementation handles the splitting of words from the phrase provided for indexing. It is able to filter out join characters like . ( etc.

Usage

In this example we would want to index a list of category objects represented Category domain object that consists of id, name and description.

public class Category {
    private String id;
    private String name;
    private String description;
    
    ... getter and setters ...
}

1. Firstly, implement a KeywordAndIdExtractor which will be required for indexing data.

public CategoryKeywordAndIdExtractor implements KeywordAndIdExtractor<Category> {

    @Override
    public String extractKeywords(Category data) {
        StringBuilder sb = new StringBuilder(data.getName());
        sb.append(" ").append(data.getDescription());
        
        return sb.toString();
    }

    @Override
    public String extractId(Category data) {
        return data.getId();
    }         
    ...

2. Configure Redis instance and load the spring bean configuration : Unit test RedisKeywordDataRepositoryTest provides spring way of setting the properties. Example properties are provided at test/resources/test-repository.properties. Note: these properties are not provided by PropertyPlaceholderConfigurer but by properties bean named repo
3. Now start indexing

    @Inject
    private RedisKeywordDataRepository redisKeywordDataRepository;

    ....
    
    public void storeCategory(Category category) {
        //store category object in data store ...
        //now index the category
        redisKeywordDataRepository.indexDataByKeywords("categoryIndex", new CategoryKeywordAndIdExtractor(), category);
    }

4. Search the indexed categories

    public List<String> searchCategories(String phrase) {
        //returns category ids
        return redisKeywordDataRepository.indexDataByKeywords("categoryIndex", phrase);
    }

How to use this library in maven

Maven dependency

<dependency>
    <groupId>com.knaptus.oss.redis</groupId>
    <artifactId>redis-dictionary</artifactId>
    <version>0.1.0-SNAPSHOT</version>
</dependency>

Note - version 1.0.0-SNAPSHOT and 1.0-SNAPSHOT are deprecated at the moment. Please check the timestamp of the artifacts to determine the latest one. These old version will be deleted as soon as we figure out how to :)

Maven repository

https://repository-addy.forge.cloudbees.com/snapshot/