Java SDK for Apache Iggy

Official Java client SDK for Apache Iggy message streaming.

This is part of the Apache Iggy monorepo. For the main project, see the root repository.

Installation

These examples target server 0.9.0. SDK 0.9.0 is on Maven Central and works with server 0.9.0. The older 0.8.0 artifact speaks the previous TCP protocol and does not work with server 0.9.0. Java 17 or newer is required.

Add the dependency to your project:

Gradle:

implementation 'org.apache.iggy:iggy:0.9.0'

Maven:

<dependency>
    <groupId>org.apache.iggy</groupId>
    <artifactId>iggy</artifactId>
    <version>0.9.0</version>
</dependency>

See Maven Central for all published versions.

Snapshot Versions

Development builds of the next release carry the version 0.9.1-SNAPSHOT. Get them from the ASF snapshot repository:

Gradle:

repositories {
    mavenCentral()
    maven {
        url = uri("https://repository.apache.org/content/repositories/snapshots/")
    }
}

dependencies {
    implementation 'org.apache.iggy:iggy:0.9.1-SNAPSHOT'
}

Maven:

<repositories>
    <repository>
        <id>apache-snapshots</id>
        <url>https://repository.apache.org/content/repositories/snapshots/</url>
        <snapshots>
            <enabled>true</enabled>
        </snapshots>
    </repository>
</repositories>

<dependencies>
    <dependency>
        <groupId>org.apache.iggy</groupId>
        <artifactId>iggy</artifactId>
        <version>0.9.1-SNAPSHOT</version>
    </dependency>
</dependencies>

Quick Start

Iggy.tcpClientBuilder() handles the routing and the session for you. Over TCP and TCP/TLS, the client keeps the consumer group membership on the coordinator. It polls each partition through a separate connection to the primary of that partition.

Start the server with the example prerequisites and matching credentials. The following snippets show alternative clients. Close a blocking client with close() or an async client with close().join() when finished.

TCP Client (Blocking)

import org.apache.iggy.Iggy;

// Create and connect with auto-login
var client = Iggy.tcpClientBuilder()
    .blocking()
    .host("localhost")
    .port(8090)
    .credentials("iggy", "iggy")
    .buildAndLogin();

// Or build, connect, and login separately
var client = Iggy.tcpClientBuilder()
    .blocking()
    .host("localhost")
    .port(8090)
    .build();
client.connect();
client.users().login("iggy", "iggy");

TCP Client (Async)

import org.apache.iggy.Iggy;

// Create async client
var asyncClient = Iggy.tcpClientBuilder()
    .async()
    .host("localhost")
    .port(8090)
    .credentials("iggy", "iggy")
    .buildAndLogin()
    .join();

// Or with manual connect and login
var asyncClient = Iggy.tcpClientBuilder()
    .async()
    .host("localhost")
    .build();
asyncClient.connect().join();
asyncClient.users().login("iggy", "iggy").join();

HTTP Client

import org.apache.iggy.Iggy;

// Using URL
var httpClient = Iggy.httpClientBuilder()
    .blocking()
    .url("http://localhost:3000")
    .credentials("iggy", "iggy")
    .buildAndLogin();

// Using host/port
var httpClient = Iggy.httpClientBuilder()
    .blocking()
    .host("localhost")
    .port(3000)
    .credentials("iggy", "iggy")
    .buildAndLogin();

TLS Support

Both TCP and HTTP clients support TLS:

// TCP with TLS
var secureClient = Iggy.tcpClientBuilder()
    .blocking()
    .host("iggy-server.example.com")
    .port(8090)
    .enableTls()
    .tlsCertificate("/path/to/ca.pem")  // Optional custom CA
    .credentials("admin", "secret")
    .buildAndLogin();

// HTTPS
var secureHttpClient = Iggy.httpClientBuilder()
    .blocking()
    .host("iggy-server.example.com")
    .port(443)
    .enableTls()
    .credentials("admin", "secret")
    .buildAndLogin();

Builder Options

The client builders support additional configuration:

var client = Iggy.tcpClientBuilder()
    .blocking()
    .host("localhost")
    .port(8090)
    .connectionTimeout(Duration.ofSeconds(10))
    .requestTimeout(Duration.ofSeconds(30))
    .retryPolicy(RetryPolicy.exponentialBackoff())
    .credentials("iggy", "iggy")
    .buildAndLogin();

Event Loop Threads

Each TCP client drives a single connection, so by default it creates an event loop group with one thread. An application that opens many clients can instead register them all on one caller-owned group. The clients never shut that group down. Close the clients first, then shut the group down:

var group = new MultiThreadIoEventLoopGroup(2, NioIoHandler.newFactory());

var producer = Iggy.tcpClientBuilder()
    .blocking()
    .eventLoopGroup(group)
    .credentials("iggy", "iggy")
    .buildAndLogin();
var consumer = Iggy.tcpClientBuilder()
    .blocking()
    .eventLoopGroup(group)
    .credentials("iggy", "iggy")
    .buildAndLogin();

// ... later
producer.close();
consumer.close();
group.shutdownGracefully();

Do not block in a completion callback. Callbacks run on the group's loops, so a blocked callback stalls every client that shares the group.

Version Information

// Get SDK version
String version = Iggy.version();  // e.g., "0.9.0"

// Get detailed version info
IggyVersion info = Iggy.versionInfo();
info.getVersion();     // Version string
info.getBuildTime();   // Build timestamp
info.getGitCommit();   // Git commit hash
info.getUserAgent();   // User-Agent string for HTTP

Exception Handling

The SDK‘s custom exception types inherit from IggyException. When you join a failed future, the cause can come back inside a CompletionException. The HTTP client’s close() method declares IOException. Handle these two boundaries as well as the specific SDK errors.

Examples

See the Java Examples directory for runnable applications demonstrating the SDK:

GettingStartedProducer: synchronous message production with batch sending
GettingStartedConsumer: synchronous consumption with polling loops
AsyncProducer: non-blocking batch production with concurrent request submission
AsyncConsumer: async consumption with backpressure and error recovery

The examples README describes blocking and async clients, CompletableFuture patterns, and thread pool management.

For Apache Flink integration, see the Flink Connector Library.

Building from Source

This project uses the Gradle Wrapper. Due to Apache Software Foundation policy, the gradle-wrapper.jar binary is not checked into the repository. Instead, the gradlew script automatically downloads it on first run.

# Build the project
./gradlew build

# Run tests
./gradlew test

The wrapper script will:

Download gradle-wrapper.jar from the official Gradle repository if missing
Verify the SHA256 checksum for security
Execute the requested Gradle command

No manual Gradle installation is required.

Note: Only the Unix shell wrapper (gradlew) is provided. On Windows, use WSL or Git Bash, or install Gradle manually.

Contributing

Before opening a pull request:

Format code: ./gradlew spotlessApply
Validate build: ./gradlew check
Use AssertJ for assertions: Write test assertions with AssertJ (assertThat(...)) instead of JUnit assertions.

These steps keep the code style compliant and make sure that all tests and checkstyle validations pass.