A2A Java SDK - JPA Database TaskStore

This module provides a JPA-based implementation of the TaskStore interface that persists tasks to a relational database instead of keeping them in memory.

The persistence is done with the Jakarta Persistence API, so this should be suitable for any JPA 3.0+ provider and Jakarta EE application server.

NOTE:

The Task instances stored in the JPA Database TaskStore are simply serialized to JSON before storing in the database, and serialized from JSON when loading from the database. This is done according to the current A2A specification version's format of Task.

Future versions of the specification might use a different format. This is not intended to be a long-term store; its usage is meant to be for the lifetime of the Task in order to have access to the Task when running in a load-balanced environment.

If you wish to keep the Task instances stored between protocol versions, you might have to implement some migration of the stored data.

Quick Start

1. Add Dependency

Add this module to your project's pom.xml:

<dependency>
    <groupId>org.a2aproject.sdk</groupId>
    <artifactId>a2a-java-extras-task-store-database-jpa</artifactId>
    <version>${a2a.version}</version>
</dependency>

The JpaDatabaseTaskStore is annotated in such a way that it should take precedence over the default InMemoryTaskStore. Hence, it is a drop-in replacement.

2. Configure Database

The following examples assume you are using PostgreSQL as your database. To use another database, adjust as needed for your environment.

For Quarkus Reference Servers

Add to your application.properties:

# Database configuration
quarkus.datasource.db-kind=postgresql
quarkus.datasource.jdbc.url=jdbc:postgresql://localhost:5432/a2a_db
quarkus.datasource.username=your_username
quarkus.datasource.password=your_password

# Hibernate configuration
quarkus.hibernate-orm.database.generation=update

For WildFly/Jakarta EE Servers

Create or update your persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="https://jakarta.ee/xml/ns/persistence" version="3.0">
    <persistence-unit name="a2a-java" transaction-type="JTA">
        <jta-data-source>java:jboss/datasources/A2ADataSource</jta-data-source>
        
        <class>org.a2aproject.sdk.extras.taskstore.database.jpa.JpaTask</class>
        <exclude-unlisted-classes>true</exclude-unlisted-classes>
        
        <properties>
            <!-- Change as required for your environment -->
            <property name="jakarta.persistence.schema-generation.database.action" value="create"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
        </properties>
    </persistence-unit>
</persistence>

3. Database Schema

The module will automatically create the required table:

CREATE TABLE a2a_tasks (
    task_id VARCHAR(255) PRIMARY KEY,
    task_data TEXT NOT NULL
);

Configuration Options

Persistence Unit Name

The module uses the persistence unit name "a2a-java". Ensure your persistence.xml defines a persistence unit with this name.