│   └── service/             # Core services
├── fess-crawler-lasta/       # LastaFlute DI integration
└── fess-crawler-opensearch/  # OpenSearch backend
```

### Key Components

#### Core Engine
- **Crawler**: Main orchestrator managing crawl execution
- **CrawlerContext**: Execution context and configuration
- **CrawlerThread**: Individual crawler thread implementation

#### Client Architecture

     * time they are accessed. The value "never" should be used to describe
     * archived URLs.
     *
     * Please note that the value of this tag is considered a hint and not a
     * command. Even though search engine crawlers may consider this information
     * when making decisions, they may crawl pages marked "hourly" less
     * frequently than that, and they may crawl pages marked "yearly" more

     *
     * This method removes characters that are not allowed in XML documents
     * according to the XML 1.0 specification. Valid characters include:
     * - Tab (0x9)
     * - Line feed (0xA)
     * - Carriage return (0xD)
     * - Any character between 0x20 and 0xD7FF
     * - Any character between 0xE000 and 0xFFFD
     * - Any character between 0x10000 and 0x10FFFF
     *

            putValue(data, "Encoding", message.getEncoding());
            putValue(data, "File-Name", message.getFileName());
            putValue(data, "From", message.getFrom());
            putValue(data, "Line-Count", message.getLineCount());
            putValue(data, "Message-ID", message.getMessageID());
            putValue(data, "Message-Number", message.getMessageNumber());

import org.opensearch.common.unit.TimeValue;
import org.opensearch.core.action.ActionListener;
import org.opensearch.core.action.ActionResponse;
import org.opensearch.index.IndexNotFoundException;
import org.opensearch.index.engine.VersionConflictEngineException;
import org.opensearch.index.query.QueryBuilder;
import org.opensearch.search.Scroll;
import org.opensearch.search.SearchHit;
import org.opensearch.threadpool.ThreadPool;

import org.codelibs.fess.suggest.util.SuggestUtil;
import org.opensearch.common.Nullable;

/**
 * The SuggestItem class represents an item used for suggestions in the Fess search engine.
 * It contains various attributes such as text, readings, fields, tags, roles, languages, kinds, and frequencies.

        assertNotNull(queryList);
        assertEquals(2, queryList.size());
    }

    @Test
    public void testCreateBulkLine() {
        // Test creating bulk line for indexing
        SuggestItem item = new SuggestItem(new String[] { "test text" }, new String[][] { { "reading1" }, { "reading2" } },
                new String[] { "field1", "field2" }, 10, // queryFreq

    <glob pattern="*.dif"/>
    <sub-class-of type="application/xml"/>
  </mime-type>

  <mime-type type="application/onix-message+xml">
    <_comment>ONline Information eXchange (ONIX) for books</_comment>
    <!-- see https://www.loc.gov/preservation/digital/formats/fdd/fdd000488.shtml -->
    <root-XML localName="ONIXMessage" namespaceURI="http://ns.editeur.org/onix/3.0/reference"/>