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
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>Configuring Options
Camel components are configured on two separate levels:
-
component level
-
endpoint level
Configuring Component Options
The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.
Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.
Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.
Configuring Endpoint Options
Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.
Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL as a type safe way of configuring endpoints.
A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.
The following two sections lists all the options, firstly for the component followed by the endpoint.
Component 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. |
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 |
Endpoint Options
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 (producer) |
Required The URL to the lucene server. |
String |
|
operation (producer) |
Required Operation to do such as insert or query. Enum values:
|
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. |
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 |
|---|---|
|
The Lucene Query to performed on the index. The query may include wildcards and phrases |
|
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 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 |