Skip to content

README.md

Latest commit

 

History

History
87 lines (64 loc) · 2.78 KB

README.md

File metadata and controls

87 lines (64 loc) · 2.78 KB

Database Session Service

JDBC-based session service implementation for ADK Java.

Features

  • No ORM Dependencies: Uses JDBC with HikariCP for connection pooling
  • Multi-Database Support: PostgreSQL, MySQL, H2 (SQLite not supported)
  • Automatic Schema Management: Flyway migrations handle table creation/updates
  • 3-Tier State Storage: Separate tables for app-level, user-level, and session-level state
  • Reactive API: RxJava 3 Single/Maybe/Completable return types

Dependencies

  • HikariCP: High-performance JDBC connection pool
  • Flyway: Database schema versioning and migration
  • Jackson: JSON serialization for events and state
  • RxJava 3: Reactive programming support

Database Schema

The service creates and manages these tables:

  • app_states: Application-level state (shared across all users)
  • user_states: User-level state (shared across user's sessions)
  • sessions: Individual session data
  • events: Event history for each session

Usage

// Create service with database URL
String dbUrl = "jdbc:postgresql://localhost:5432/adk?user=postgres&password=secret";
try (DatabaseSessionService sessionService = new DatabaseSessionService(dbUrl)) {
    
    // Create a session
    Session session = sessionService.createSession(
        "myApp", 
        "user123", 
        new ConcurrentHashMap<>(), 
        null
    ).blockingGet();
    
    // Append an event
    Event event = Event.builder()
        .id(UUID.randomUUID().toString())
        .invocationId("inv-1")
        .timestamp(System.currentTimeMillis())
        .build();
        
    Event appendedEvent = sessionService.appendEvent(session, event).blockingGet();
}

Supported Databases

  • PostgreSQL: Full support with JSONB
    • URL: jdbc:postgresql://host:port/database?user=...&password=...
  • MySQL: Full support with JSON
    • URL: jdbc:mysql://host:port/database?user=...&password=...
  • H2: For testing and development
    • URL: jdbc:h2:mem:testdb or jdbc:h2:file:./data/mydb
  • Cloud Spanner: Full support
    • URL: jdbc:cloudspanner:/projects/PROJECT_ID/instances/INSTANCE_ID/databases/DATABASE_ID
  • SQLite: NOT supported (no UPSERT support)

State Management

State is stored across three tables with merge priority:

  1. App State (lowest priority): app:key prefix
  2. User State (medium priority): user:key prefix
  3. Session State (highest priority): No prefix

When retrieving a session, states are merged: app → user → session (higher priority overwrites).

Configuration

Optional properties can be passed to the constructor:

Map<String, Object> props = new HashMap<>();
props.put("connectionTimeout", 30000);
props.put("maximumPoolSize", 10);

DatabaseSessionService service = new DatabaseSessionService(dbUrl, props);