Hekate.io

Java Library for Distributed Services

License

Open source Apache License v2.0

Features

• Distributed Service Discovery

  • Decentralized Service Discovery (based on performance-optimized Gossip protocol)
  • Easy integration into existing infrastructure
    • Clouds (based on Apache JClouds)
      • Amazon EC2 and S3
      • Google Cloud Storage and Compute Engine
      • Azure Blob Storage
      • etc
    • Kubernetes
    • ZooKeeper
    • Etcd
    • Consul
    • IP Multicast
    • Shared Database (JDBC-based)
    • Shared File System
  • User-defined Service Properties and Roles
  • Cluster Event Listeners
  • Service Topology Views and Filtering APIs
  • Health Monitoring and Split-brain Detection

• Messaging

  • Synchronous and Asynchronous Messaging (backed by Netty)
  • Cluster-aware Load Balancing and Routing
  • SSL/TLS Encryption of Network Communications (optional)
  • Back Pressure Policies
  • Error Retry Policies
  • Pluggable Serialization
    • Kryo
    • FST
    • Protocol Buffers (work in progress)
    • JDK Serialization
    • Manual Serialization

• Remote Procedure Calls (RPC)

  • Type-safe Invocation of Remote Java Services
  • Automatic Discovery and Load Balancing
  • Synchronous and Asynchronous APIs
  • Multi-node Broadcasting and Aggregation of Results
  • Back Pressure Policies
  • Error Retry Policies
  • ...and everything from the "Messaging" section above:)

• Cluster-wide Singleton Service (aka Leader Election )

  • Decentralized Leader Election
  • Followers are Aware of the Current Leader
  • Leader can Dynamically Yield Leadership

• Distributed Locks

  • Synchronous and Asynchronous Reentrant Locks
  • Decentralized Lock Management
  • Configurable Lock Groups (aka Lock Regions)

• Spring Boot/Framework Support (optional)

  • Spring Boot Auto-configurations and @Annotations
  • Spring-compliant Beans
  • Spring XML Schema to Simplify Configuration

• Metrics

  • Internal Metrics Recording and Publishing via Micrometer.io

• Raft-based Replicated State Machines (planned)

Documentation

• Javadocs (Follow the White Rabbit [« start here] marks).
• Reference Guide (coming soon...)
• Spring Boot Properties Reference

Code Examples

Quickstart for Standalone Java Application

public class MyApplication{
    public static void main(String[] args) throws Exception {
        Hekate hekate = new HekateBootstrap()
            .withNamespace("my-cluster")
            .withNodeName("my-node")
            .join();
        
        System.out.println("Cluster topology: " + hekate.cluster().topology());
    }
}

Quickstart for Spring Boot Application

@EnableHekate // <-- Enable Hekate integration.
@SpringBootApplication
public class MyApplication {
    @Autowired
    private Hekate hekate;

    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class, args);
    }
    
    @PostConstruct
    public void start(){
        System.out.println("Cluster topology: " + hekate.cluster().topology());
    }
}

More Examples:

Please see the hekate-io/hekate-examples project for more examples.

Maven artifacts

• For projects based on Spring Boot:

<dependency>
    <groupId>io.hekate</groupId>
    <artifactId>hekate-spring-boot</artifactId>
    <version>4.0.0</version>
</dependency>

• For projects based on Spring Framework:

<dependency>
    <groupId>io.hekate</groupId>
    <artifactId>hekate-spring</artifactId>
    <version>4.0.0</version>
</dependency>

• For standalone applications:

<dependency>
    <groupId>io.hekate</groupId>
    <artifactId>hekate-core</artifactId>
    <version>4.0.0</version>
</dependency>

• Other artifacts:
  • Cluster Bootstrapping (seed node discovery)
    • hekate-jclouds-core - Integration with Apache JClouds for cloud environments.
    • hekate-jclouds-aws - Extended integration with Amazon EC2 cloud.
    • hekate-kubernetes - Integration with Kubernetes
    • hekate-zookeeper - Integration with Apache ZooKeeper
    • hekate-etcd - Integration with Etcd
    • hekate-consul - Integration with Consul
  • Serialization Codecs
    • hekate-codec-kryo - Integration with Kryo for data serialization.
    • hekate-codec-fst - Integration with FST for data serialization.

How to build

Software requirements:

• Latest stable Java SDK (8+)
• Latest stable Docker (required for tests only)

Build (no tests):

• cd to the project's root folder
• run ./mvnw clean package -DskipTests=true

Build (with tests):

• cd to the project's root folder
• make a copy of test.properties file with name my_test.properties
• edit my_test.properties according to your environment
• run docker-compose up -d to prepare Docker-based testing infrastructure
• run ./mvnw clean package

Release History

• v.4.0.0 (20-Mar-2021) - [release notes]

• v.3.11.0 (24-Oct-2020) - [release notes]

• v.3.10.0 (4-Jul-2020) - [release notes]

• v.3.9.0 (8-May-2020) - [release notes]

• v.3.8.0 (29-Feb-2020) - [release notes]

• v.3.7.0 (3-Feb-2020) - [release notes]

• v.3.6.0 (13-Oct-2019) - [release notes]

• v.3.5.0 (14-Aug-2019) - [release notes]

• v.3.4.1 (4-Jul-2019) - [release notes]

• v.3.4.0 (29-Jun-2019) - [release notes]

• v.3.3.0 (19-Apr-2019) - [release notes]

• v.3.2.0 (5-Apr-2019) - [release notes]

• v.3.1.0 (28-Mar-2019) - [release notes]

• v.3.0.0 (19-Mar-2019) - [release notes]

• v.2.6.0 (22-Aug-2018) - [release notes]

• v.2.5.0 (4-Aug-2018) - [release notes]

• v.2.4.1 (15-Jul-2018) - [release notes]

• v.2.4.0 (15-Jul-2018) - [release notes]

• v.2.3.1 (18-May-2018) - [release notes]

• ...and so on