Open Source Full-text Search Server - Fess Development Overview

This page provides an overview of Fess development and basic information for getting started with development.

Overview

Fess is an open-source full-text search server developed in Java. It aims to make enterprise search easy to build, providing powerful search capabilities and an easy-to-use administration interface.

Fess Features

  • Easy Setup: Can be started immediately with a Java environment

  • Powerful Crawler: Supports diverse data sources including websites, file systems, and databases

  • Japanese Support: Optimized for Japanese full-text search

  • Extensibility: Functional extensions possible through plugins

  • REST API: Search capabilities can be used from other applications

Technology Stack

Fess is developed using the following technologies.

Target Versions

This documentation targets the following versions:

  • Fess: 15.3.0

  • Java: 21 or later

  • OpenSearch: 3.3.0

  • Maven: 3.x

Main Technologies and Frameworks

Java 21

Fess is an application that runs on Java 21 or later. It leverages the latest Java features to improve performance and maintainability.

  • Recommended: Eclipse Temurin 21 (formerly AdoptOpenJDK)

  • Minimum version: Java 21

LastaFlute

LastaFlute is the framework used in Fess’s web application layer.

Main features:

  • DI (Dependency Injection) container

  • Action-based web framework

  • Validation

  • Message management

  • Configuration management

Learning resources:

DBFlute

DBFlute is an O/R mapping tool for database access. In Fess, it is used to automatically generate Java code from OpenSearch schemas.

Main features:

  • Type-safe SQL builder

  • Automatic code generation from schemas

  • Automatic database documentation generation

Learning resources:

OpenSearch

OpenSearch is the distributed search and analytics engine used as Fess’s search engine.

Supported version: OpenSearch 3.3.0

Required plugins:

  • opensearch-analysis-fess: Fess-specific morphological analysis plugin

  • opensearch-analysis-extension: Additional language analysis features

  • opensearch-minhash: Similar document detection

  • opensearch-configsync: Configuration synchronization

Learning resources:

Maven

Maven is used as Fess’s build tool.

Main uses:

  • Dependency library management

  • Build process execution

  • test execution

  • Package creation

Development Tools

Required Knowledge

Basic Knowledge

The following knowledge is required for Fess development:

Required

  • Java programming: Classes, interfaces, generics, lambda expressions, etc.

  • Object-oriented: Inheritance, polymorphism, encapsulation

  • Maven: Basic commands and understanding of pom.xml

  • Git: clone, commit, push, pull, branch, merge, etc.

Recommended

  • LastaFlute: Concepts of Action, Form, Service

  • DBFlute: How to use Behavior, ConditionBean

  • OpenSearch/Elasticsearch: Basics of index, mapping, query

  • Web development: HTML, CSS, JavaScript (especially for frontend development)

  • Linux commands: Development and debugging in server environment

Learning Resources

The following resources are useful for first-time Fess development:

Official Documentation

Community

Source Code

Reading actual code is the most effective learning method:

  • Start by reading small features

  • Trace code execution using a debugger

  • Reference existing test code

Basic Development Flow

Fess development generally proceeds as follows:

  1. Check/Create Issue

    Check GitHub Issues and decide what to work on. Create an Issue for new features or bug fixes.

  2. Create Branch

    Create a working branch:

    git checkout -b feature/my-new-feature

  3. Coding

    Implement features or fix bugs.

  4. testing

    Create and run unit tests to verify changes work correctly.

  5. Commit

    Commit changes:

    git add .
git commit -m "Add new feature"

  6. Pull Request

    Push to GitHub and create a pull request:

    git push origin feature/my-new-feature

See Development Workflow for details.

Project Structure Overview

Fess source code has the following structure:

fess/
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── org/codelibs/fess/
│   │   │       ├── app/           # Web application layer
│   │   │       │   ├── web/       # Search screen
│   │   │       │   └── service/   # Service layer
│   │   │       ├── crawler/       # Crawler features
│   │   │       ├── es/            # OpenSearch related
│   │   │       ├── helper/        # Helper classes
│   │   │       ├── job/           # Job processing
│   │   │       ├── util/          # Utilities
│   │   │       └── FessBoot.java  # Boot class
│   │   ├── resources/
│   │   │   ├── fess_config.properties
│   │   │   ├── fess_config.xml
│   │   │   └── ...
│   │   └── webapp/
│   │       └── WEB-INF/
│   │           └── view/          # JSP files
│   └── test/
│       └── java/                  # test code
├── pom.xml                        # Maven configuration file
└── README.md

Main Packages

app

Code for the web application layer. Includes Action, Form, Service for admin and search screens.

crawler

Code for data collection features such as web crawler, file crawler, and data store crawler.

es

Code for OpenSearch integration. Includes index operations and search query construction.

helper

Helper classes used throughout the application.

job

Code for jobs executed on a schedule. Includes crawl jobs, index optimization jobs, etc.

See Architecture and Code Structure for details.

Development Environment Quick Start

This explains how to set up the development environment and run Fess with minimal steps.

Prerequisites

  • Java 21 or later is installed

  • Git is installed

  • Maven 3.x is installed

Steps

  1. Clone Repository

    git clone https://github.com/codelibs/fess.git
cd fess

  2. Download OpenSearch Plugins

    mvn antrun:run

  3. Run

    Run from Maven:

    mvn compile exec:java

    Or, run the org.codelibs.fess.FessBoot class from your IDE (Eclipse, IntelliJ IDEA, etc.).

  4. Access

    Access the following in a browser:

See Development Environment Setup for detailed setup instructions.

Development Tips

Debug Execution

When running debug in IDE, execute the FessBoot class. You can trace code execution in detail by setting breakpoints.

Hot Deploy

LastaFlute can reflect some changes without restarting. However, changes to class structure require a restart.

Checking Logs

Logs are output to the target/fess/logs/ directory. Check log files when problems occur.

Operating OpenSearch

The embedded OpenSearch is located in target/fess/es/. You can also debug by calling OpenSearch API directly:

# Check indices
curl -X GET http://localhost:9201/_cat/indices?v

# Search documents
curl -X GET http://localhost:9201/fess.search/_search?pretty

Community and Support

Questions and Consultation

For questions or consultation during development, use the following:

How to Contribute

See Contribution Guide for how to contribute to Fess.

Next Steps

When you’re ready to set up the development environment, proceed to Development Environment Setup.

Also refer to the following documents for detailed information:

References

Official Resources

Technical Documentation

Community