What is Liferay

Liferay 7.4 is the latest DXP (Digital Experience Platform) version from Liferay, built on OSGi (Open Service Gateway Initiative) architecture. As a Liferay developer, you’ll work with a modular, enterprise-grade platform for building digital experiences, portals, intranets, and custom web applications.

graph TD
    A[Liferay 7.4 Architecture] --> B[OSGi Container]
    A --> C[Modularity]
    A --> D[Microservices]
    A --> E[APIs]
    B --> F[Bundles]
    C --> G[Modules]
    D --> H[Service Builder]
    E --> I[REST/SOAP/GraphQL]

Core Concepts

1. OSGi and Modular Architecture

Liferay 7.4 uses OSGi for:

• Dynamic module system
• Service registry
• Lifecycle management
• Dependency management

2. Workspace Structure

A standard Liferay workspace contains:

liferay-workspace/
├── configs/
├── gradle/
├── modules/
│   ├── apps/
│   ├── core/
│   └── themes/
├── themes/
└── build.gradle

Development Components

1. Modules

The building blocks of Liferay applications:

classDiagram
    class Module {
        +bnd.bnd
        +build.gradle
        +src/main/java
        +src/main/resources
    }
    Module --> ServiceComponent : contains
    Module --> API : exposes

2. Service Builder

Liferay’s ORM and service generation tool:

1. Define entities in service.xml
2. Run gradle buildService
3. Service Builder generates:
   • Model classes
   • Persistence layer
   • Service layers
   • API interfaces

3. MVC Portlet

Traditional portlet development approach:

@Component(
    immediate = true,
    property = {
        "javax.portlet.name=" + MyPortletKeys.MY_PORTLET,
        "mvc.command.name=/my/action"
    },
    service = MVCActionCommand.class
)
public class MyActionCommand implements MVCActionCommand {
    // Your action code
}

4. Frontend Development

Liferay 7.4 supports multiple approaches:

• Traditional: JSP, FreeMarker
• Modern: React, Angular, Vue.js via Liferay JS Toolkit
• Web Components: Using Clay UI and Metal.js

Key APIs and Services

1. Headless APIs

Liferay 7.4 provides extensive headless delivery:

sequenceDiagram
    Client->>+Liferay: GET /o/api/resource
    Liferay->>+Service: Process request
    Service-->>-Liferay: Return data
    Liferay-->>-Client: JSON/XML response

2. Workflow Framework

Customizable workflow engine:

• Kaleo workflow engine
• Create custom workflow handlers
• Integrate with external systems

3. Search and Indexing

• Elasticsearch integration
• Custom document fields
• Search facets and filters

Development Workflow

1. Setup

1. Install Liferay Workspace
2. Configure Gradle properties
3. Set up target platform

2. Development Cycle

graph LR
    A[Create Module] --> B[Implement Logic]
    B --> C[Build/Deploy]
    C --> D[Test]
    D --> E[Debug]
    E --> F[Iterate]

3. Deployment Options

• Local development (Docker/Standalone)
• On-premise servers
• Cloud (Liferay DXP Cloud)

Advanced Topics

1. Customization Techniques

• Extend core services using OSGi components
• Override JSPs with module fragments
• Create custom field types
• Develop custom asset renderers

2. Performance Considerations

• Cluster-aware coding
• Caching strategies
• Database optimization
• Frontend performance

3. Security Best Practices

• Implement permission checking
• Secure service endpoints
• Validate all inputs
• Follow OWASP guidelines

Tools and Utilities

1. Liferay Developer Studio

• Eclipse-based IDE
• Code templates
• Debugging tools

2. Blade CLI

blade create -t mvc-portlet -p com.example.my.portlet my-portlet-project

3. Gogo Shell

For runtime inspection and management:

g! lb | grep my.module
g! services | grep MyService

Testing Strategies

1. Unit tests (JUnit/Mockito)
2. Integration tests (Arquillian)
3. UI tests (Selenium)
4. Performance tests (JMeter)

Migration Path

When upgrading from previous versions:

1. Analyze deprecated APIs
2. Convert plugins to OSGi modules
3. Update dependencies
4. Test compatibility

Sample Module Structure

my-custom-module/
├── bnd.bnd
├── build.gradle
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/example/
│   │   │       ├── constants/
│   │   │       ├── portlet/
│   │   │       └── service/
│   │   └── resources/
│   │       ├── META-INF/
│   │       │   └── resources/
│   │       └── service.properties
│   └── test/
└── service.xml

Continuous Integration

graph TB
    A[Code Commit] --> B[Build]
    B --> C[Unit Tests]
    C --> D[Integration Tests]
    D --> E[Package]
    E --> F[Deploy to Test]
    F --> G[UI Tests]
    G --> H[Production]

Conclusion

As a Liferay 7.4 developer, you’re working with a powerful, modular platform that requires understanding of:

• OSGi concepts
• Modern web development
• Service-oriented architecture
• Headless delivery
• Cloud-native principles

The platform offers flexibility but requires disciplined development practices to leverage its full potential.