Saturday, May 2, 2020

How to enable case insensitive search in AEM with Lucene?

How to enable case insensitive search in AEM with Lucene?


This tutorial explains how to enable case insensitive search in AEM with Lucene.

I have two nodes with property "id" under /content/sampledata with same value in different case e.g TEST and test

aem-case-insensitive-search-with-lucene1

aem-case-insensitive-search-with-lucene

By default, the Lucene search is case sensitive so the query will return only the matching node - the node matching with value "test"

aem-case-insensitive-search-with-lucene

The case insensitive can be enabled through analyzers in Lucene index

Refer the following URL to configure the custom Lucene index - https://www.albinsblog.com/2020/04/oak-lucene-index-improve-query-in-aem-configure-lucene-index.html#.Xu7oD2hKjb1

Analysis, in Lucene, is the process of converting field text into its most fundamental indexed representation, terms. These terms are used to determine what documents match a query during searching.

An analyzer tokenizes text by performing any number of operations on it, which could include extracting words, discarding punctuation, removing accents from characters, lowercasing (also called normalizing), removing common words, reducing words to a root form (stemming), or changing words into the basic form (lemmatization).

This process is also called tokenization, and the chunks of text pulled from a stream of text are called tokens. Tokens, combined with their associated field name, are terms.

In Lucene, an analyzer is a java class that implements a specific analysis. Analysis occurs any time text needs to be converted into terms, which in Lucene’s core is at two spots: during indexing and when searching.

An analyzer chain starts with a Tokenizer, to produce initial tokens from the characters read from a Reader, then modifies the tokens with any number of chained TokenFilters.

Let’s see the some important built-in analyzer available in Lucene bundle:

WhitespaceAnalyzer, as the name implies, splits text into tokens on whitespace characters and makes no other effort to normalize the tokens. It doesn’t lowercase each token. 

SimpleAnalyzer first splits tokens at nonletter characters, then lowercases each token. Be careful! This analyzer quietly discards numeric characters but keeps all other characters. 

StopAnalyzer is the same as SimpleAnalyzer, except it removes common words. By default, it removes common words specific to the English language (the, a, etc.), though you can pass in your own set.

KeywordAnalyzer treats entire text as a single token. 

StandardAnalyzer is Lucene’s most sophisticated core analyzer. It has quite a bit of logic to identify certain kinds of tokens, such as company names, email addresses, and hostnames. It also lowercases each token and removes stop words and punctuation. 

The built-in analyzers can be used directly by specifying the class name or the analyzers can be composed with tokenizer and series of filters – there are multiple Tokenizers e.g Standard, Keyword, CharTokenizers and Token Filters e.g Stop, LowerCase,Standard 

org.apache.lucene.analysis.standard.StandardAnalyzer 

org.apache.lucene.analysis.core.SimpleAnalyzer

There are multiple standard analyzers, tokenizers and Token Filters, custom analyzers/Tokenizer/TokenFilters can be created if required. 

The analyzers is configured via the analyzers node (of type nt:unstructured) inside the oak:index definition. 

The default analyzer for an index is configured in the default child of the analyzer’s node(of type nt:unstructured). 

Create a child node with name "tokenizer" of type "nt:untstrutured" under default node and add the property "name" with value "Standard"

aem-case-insensitive-search-with-lucene

Create a child node with name "filters" of type "nt:untstrutured" under default node.

Create a child node with name "LowerCase" of type "nt:untstrutured" 

This will index the data by lower casing and also match data by lower casing during the search.

The configurations are ready now, let us index the data. Change the value of reindex property under the custom index to true - this will initiate the re-indexing, the property value will be changed to false once the re-indexing is initiated

aem-case-insensitive-search-with-lucene

Let me now re-execute the query, this time the query returns both nodes with uppercase and lowercase values(TEST and test)

aem-case-insensitive-search-with-lucene



Saturday, April 25, 2020

AEM Core components deep dive | How to extend AEM core components | Proxy Components in AEM

AEM Core components deep dive | How to extend AEM core components | Proxy Components in AEM


This tutorial explains the details on AEM core components

In AEM, we use either custom or OOTB components to build the website, these components are called as WCM(Web Content Management) components.

aem-wcm-core-components

Core components 


  •  introduced in AEM 6.2 but are strongly recommended to use from 6.3
  •  provides robust extensible base components
  •  built on the latest technology and follows the best practices
  •  adhering to accessibility guidelines and compliant with the WCAG 2.0 AA standard
  •  makes page authoring more flexible and customizable
  • simple to extend to offer custom functionalities


Core components - Features


aem-wcm-core-components

Core Components - Architecture


aem-wcm-core-components


  • Design dialog defines what authors can or cannot do it in the edit dialog
  • Edit dialog shows authors only options they are allowed to use
  • Sling model verifies and prepares the content for the view(template)
  • The result of the sling model can be serialized to JSON for SPA use cases
  • HTL renders the HTML server-side for traditional server-side rendering
  • The HTML output is semantic, accessible, search-engine optimized and easy to style.
The Core components follows the MVC (Model View Controller) design pattern.

aem-wcm-core-components


aem-wcm-core-components

The Controller(Content) refers the proxy component (View), the proxy component is extended from WCM core components. Proxy Components are site-specific components which are inherited from core components, these are called as proxy component as no implementation is required but refers the core component as the resourceSuperType, can be extended as required.

The core components refers the Sling Model (Model) to retrieve the required data for rendering. 

The Controller(Content) also refers the templates and configuration policies.

The Delegate pattern can be used to extend the model class for the core component, the responsibility of the model class is delegated to the implementations based on the resource type.

The core components uses the model interfaces and delegated to the right model implementation at runtime based on the resourceType in the model implementation.

 Enable Core Components


The Core Components are open sourced through github, the components implementation and details can be referred from https://github.com/adobe/aem-core-wcm-components

Either one of the below approach can be followed to install the Core Components to AEM
  • Install through package manager
  • Include through code package


Install through package manager


The latest version is listed in the github page, the previous versions can be accessed by clicking on "Historical System Requirements"

aem-wcm-core-components

aem-wcm-core-components


Click on the version based on the system requirement and download the packages

aem-wcm-core-components

Install the downloaded package through package manager, the core components are now enabled to the AEM instance

aem-wcm-core-components