Lucene

Since Camel 2.2

Only producer is supported

The Lucene component is based on the Apache Lucene project. Apache Lucene is a powerful high-performance, full-featured text search engine library written entirely in Java. For more details about Lucene, please see the following links

The lucene component in camel facilitates integration and utilization of Lucene endpoints in enterprise integration patterns and scenarios. The lucene component does the following

  • builds a searchable index of documents when payloads are sent to the Lucene Endpoint

  • facilitates performing of indexed searches in Camel

This component only supports producer endpoints.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-lucene</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

URI format

lucene:searcherName:insert[?options]
lucene:searcherName:query[?options]

You can append query options to the URI in the following format, ?option=value&option=value&…​

Insert Options

The Lucene component supports 7 options, which are listed below.

Name Description Default Type

analyzer (producer)

An Analyzer builds TokenStreams, which analyze text. It thus represents a policy for extracting index terms from text. The value for analyzer can be any class that extends the abstract class org.apache.lucene.analysis.Analyzer. Lucene also offers a rich set of analyzers out of the box

Analyzer

indexDir (producer)

A file system directory in which index files are created upon analysis of the document by the specified analyzer

File

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

maxHits (producer)

An integer value that limits the result set of the search operation

int

srcDir (producer)

An optional directory containing files to be used to be analyzed and added to the index at producer startup.

File

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

boolean

config (advanced)

To use a shared lucene configuration

LuceneConfiguration

The Lucene endpoint is configured using URI syntax:

lucene:host:operation

with the following path and query parameters:

Path Parameters (2 parameters):

Name Description Default Type

host

Required The URL to the lucene server

String

operation

Required Operation to do such as insert or query. There are 2 enums and the value can be one of: insert, query

LuceneOperation

Query Parameters (5 parameters):

Name Description Default Type

analyzer (producer)

An Analyzer builds TokenStreams, which analyze text. It thus represents a policy for extracting index terms from text. The value for analyzer can be any class that extends the abstract class org.apache.lucene.analysis.Analyzer. Lucene also offers a rich set of analyzers out of the box

Analyzer

indexDir (producer)

A file system directory in which index files are created upon analysis of the document by the specified analyzer

File

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

maxHits (producer)

An integer value that limits the result set of the search operation

int

srcDir (producer)

An optional directory containing files to be used to be analyzed and added to the index at producer startup.

File

Sending/Receiving Messages to/from the cache

Message Headers

Header Description

QUERY

The Lucene Query to performed on the index. The query may include wildcards and phrases

RETURN_LUCENE_DOCS

Set this header to true to include the actual Lucene documentation when returning hit information.

Lucene Producers

This component supports 2 producer endpoints.

insert - The insert producer builds a searchable index by analyzing the body in incoming exchanges and associating it with a token ("content"). query - The query producer performs searches on a pre-created index. The query uses the searchable index to perform score & relevance based searches. Queries are sent via the incoming exchange contains a header property name called 'QUERY'. The value of the header property 'QUERY' is a Lucene Query. For more details on how to create Lucene Queries check out Query Parser Classic syntax

Lucene Processor

There is a processor called LuceneQueryProcessor available to perform queries against lucene without the need to create a producer.

Lucene Usage Samples

Example 1: Creating a Lucene index

RouteBuilder builder = new RouteBuilder() {
    public void configure() {
       from("direct:start").
           to("lucene:whitespaceQuotesIndex:insert?
               analyzer=#whitespaceAnalyzer&indexDir=#whitespace&srcDir=#load_dir").
           to("mock:result");
    }
};

Example 2: Loading properties into the JNDI registry in the Camel Context

CamelContext context = new DefaultCamelContext(createRegistry());
Registry registry = context.getRegistry();
registry.bind("whitespace", new File("./whitespaceIndexDir"));
registry.bind("load_dir", new File("src/test/resources/sources"));
registry.bind("whitespaceAnalyzer", new WhitespaceAnalyzer());

Example 2: Performing searches using a Query Producer

RouteBuilder builder = new RouteBuilder() {
    public void configure() {
       from("direct:start").
          setHeader("QUERY", constant("Seinfeld")).
          to("lucene:searchIndex:query?
             analyzer=#whitespaceAnalyzer&indexDir=#whitespace&maxHits=20").
          to("direct:next");

       from("direct:next").process(new Processor() {
          public void process(Exchange exchange) throws Exception {
             Hits hits = exchange.getIn().getBody(Hits.class);
             printResults(hits);
          }

          private void printResults(Hits hits) {
              LOG.debug("Number of hits: " + hits.getNumberOfHits());
              for (int i = 0; i < hits.getNumberOfHits(); i++) {
                 LOG.debug("Hit " + i + " Index Location:" + hits.getHit().get(i).getHitLocation());
                 LOG.debug("Hit " + i + " Score:" + hits.getHit().get(i).getScore());
                 LOG.debug("Hit " + i + " Data:" + hits.getHit().get(i).getData());
              }
           }
       }).to("mock:searchResult");
   }
};

Example 3: Performing searches using a Query Processor

RouteBuilder builder = new RouteBuilder() {
    public void configure() {
        try {
            from("direct:start").
                setHeader("QUERY", constant("Rodney Dangerfield")).
                process(new LuceneQueryProcessor("target/stdindexDir", analyzer, null, 20)).
                to("direct:next");
        } catch (Exception e) {
            e.printStackTrace();
        }

        from("direct:next").process(new Processor() {
            public void process(Exchange exchange) throws Exception {
                Hits hits = exchange.getIn().getBody(Hits.class);
                printResults(hits);
            }

            private void printResults(Hits hits) {
                LOG.debug("Number of hits: " + hits.getNumberOfHits());
                for (int i = 0; i < hits.getNumberOfHits(); i++) {
                    LOG.debug("Hit " + i + " Index Location:" + hits.getHit().get(i).getHitLocation());
                    LOG.debug("Hit " + i + " Score:" + hits.getHit().get(i).getScore());
                    LOG.debug("Hit " + i + " Data:" + hits.getHit().get(i).getData());
                }
            }
       }).to("mock:searchResult");
   }
};

Spring Boot Auto-Configuration

When using lucene with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-lucene-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 8 options, which are listed below.

Name Description Default Type

camel.component.lucene.analyzer

An Analyzer builds TokenStreams, which analyze text. It thus represents a policy for extracting index terms from text. The value for analyzer can be any class that extends the abstract class org.apache.lucene.analysis.Analyzer. Lucene also offers a rich set of analyzers out of the box. The option is a org.apache.lucene.analysis.Analyzer type.

Analyzer

camel.component.lucene.autowired-enabled

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

Boolean

camel.component.lucene.config

To use a shared lucene configuration. The option is a org.apache.camel.component.lucene.LuceneConfiguration type.

LuceneConfiguration

camel.component.lucene.enabled

Whether to enable auto configuration of the lucene component. This is enabled by default.

Boolean

camel.component.lucene.index-dir

A file system directory in which index files are created upon analysis of the document by the specified analyzer.

File

camel.component.lucene.lazy-start-producer

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

Boolean

camel.component.lucene.max-hits

An integer value that limits the result set of the search operation.

Integer

camel.component.lucene.src-dir

An optional directory containing files to be used to be analyzed and added to the index at producer startup.

File
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