Introduction to Cadence Java Client
The Cadence Java Client is part of the larger Cadence project, which is an initiative developed by Uber Engineering. It's designed to help developers manage and execute asynchronous long-running business logic in a way that is both scalable and resilient. The focus of this particular client is on facilitating these tasks within Java applications, providing a robust framework to write workflows and activities efficiently.
What is Cadence?
Cadence is a distributed system that acts as an orchestration engine. This means it helps coordinate various tasks across a network, ensuring they are carried out in the correct sequence and handle any necessary retries if issues arise. It is inherently scalable and durable, meaning that it can handle an increasing amount of work or a growing dataset without losing functionality.
The Role of Cadence Java Client
The cadence-client is specifically for Java developers, enabling them to define and control these workflows programmatically. This involves creating, managing, and executing sequences of tasks or processes called workflows, which can span across multiple services and operations. If you're looking to integrate similar functionality in Go, there is a corresponding Go Cadence Client.
Getting Started with the Cadence Java Client
Sample Workflows
To aid developers new to the Cadence Java Client, there are several sample workflows available. These examples demonstrate how to implement specific features and are hosted in the Java Cadence samples repository.
Setting Up the Cadence Server
To run Cadence workflows, you'll need a running Cadence server. The recommended way to start is by using Docker Compose. You can download and run it with a simple command:
curl -O https://raw.githubusercontent.com/uber/cadence/master/docker/docker-compose.yml
docker-compose up
If you encounter issues, additional setup instructions are available in the Cadence GitHub repository.
Command Line Interface
For interaction with the Cadence system, there's a Command Line Interface (CLI) available both as an executable and a Docker image. This tool helps developers interact with the Cadence service, manage workflows, and debug activities.
Configuring Your Java Project
To incorporate the cadence-client in your Java project, you need to add it as a dependency. For Maven projects, include the following in your pom.xml:
<dependency>
<groupId>com.uber.cadence</groupId>
<artifactId>cadence-client</artifactId>
<version>V.V.V</version>
</dependency>
For Gradle projects, add this dependency to your build.gradle:
compile group: 'com.uber.cadence', name: 'cadence-client', version: 'V.V.V'
Documentation and Community
Comprehensive documentation is available to assist developers in harnessing the full potential of the Cadence Java Client. Detailed usage guides and examples can be accessed here, while API-specific documentation is available through Javadocs.
Contributing
The Cadence Java Client is open-source, and the community is encouraged to contribute. Whether by reporting issues, submitting pull requests, or suggesting new features, all forms of collaboration are welcomed. Developers interested in contributing can review the contribution guidelines.
License
The Cadence Java Client is distributed under the Apache License. For more details on the terms and conditions, please refer to the LICENSE file.
This introduction should equip you with a foundation to explore the Cadence Java Client further, enabling you to integrate its powerful orchestration capabilities into your own Java projects.