Provides the Java API for the Open Workflow Specification

With the SDK you can:

• Read workflow JSON and YAML definitions
• Write workflow definitions in JSON and YAML formats.
• Test your workflow definitions using the reference implementation.

Note: 6.0.0.Final (planned for spec v0.9) is intentionally skipped to leave room for anyone who wants to work on it.

To build project and run tests locally:

git clone https://github.com/open-workflow-specification/sdk-java.git
mvn clean install

The project uses Google's code styleguide. Your changes should be automatically formatted during the build.

Add the following dependencies to your pom.xml dependencies section:

<dependency>
    <groupId>org.openworkflow.sdk</groupId>
    <artifactId>openworkflow-api</artifactId>
    <version>RELEASE_VERSION</version>
</dependency>

Add the following dependencies to your build.gradle dependencies section:

implementation("org.openworkflow.sdk:openworkflow-api:RELEASE_VERSION")

There are, roughly speaking, two kind of users of this SDK:

• Those ones interested on implementing their own runtime using Java.
• Those ones interested on using the provided runtime reference implementation.

For those ones interested on implementing their own runtime, this SDK provides an easy way to load an in memory representation of a given workflow definition. This in-memory representation consists of a hierarchy of POJOS directly generated from the Open Workflow specification schema, which ensures the internal representation is aligned with the specification schema. The root of the hierarchy is org.openworkflow.sdk.api.types.Workflow class

You can read a Workflow definition from JSON/YAML source:

Let's say you have a simple YAML based workflow definition in a file name simple.yaml located in your working dir:

document:
  dsl: 1.0.0-alpha1
  namespace: default
  name: implicit-sequence
do:
  setRed:
    set:
      colors: '${ .colors + [ "red" ] }'
  setGreen:
    set:
      colors: '${ .colors + [ "green" ] }'
  setBlue:
    set:
      colors: '${ .colors + [ "blue" ] }'

To parse it and get a Workflow instance you can do:

try (InputStream in = new FileInputStream("simple.yaml")) {
   Workflow workflow = WorkflowReader.readWorkflow (in, WorkflowFormat.YAML);
   // Once you have the Workflow instance you can use its API to inspect it
}

By default, Workflows are not validated against the schema (performance being the priority). If you want to enable validation, you can do that by using:

try (InputStream in = new FileInputStream("simple.yaml")) {
   Workflow workflow = WorkflowReader.validation().readWorkflow (in, WorkflowFormat.YAML);
   // Once you have the Workflow instance you can use its API to inspect it
}

For additional reading helper methods, including the one to read a workflow definition from classpath, check WorkflowReader class.

Given a Workflow instance, you can store it using JSON or YAML format. For example, to store a workflow using json format in a file called simple.json, you write

try (OutputStream out = new FileOutputStream("simple.json")) {
    WorkflowWriter.writeWorkflow(out, workflow, WorkflowFormat.JSON);
}

For additional writing helper methods, check WorkflowWriter class.

The openworkflow-api module depends heavily on Jackson for loading file content into an in-memory POJO. For users who use a JSON handling library other than Jackson, the openworkflow-types module contains Java POJOs generated from the OpenWorkflow schema without any Jackson annotations. Using this module as a dependency, they can build a reader/writer module equivalent to openworkflow-api with their preferred JSON library.

The reference implementation provides a ready-to-use runtime that supports the Open Workflow Specification. It includes a workflow execution engine, validation utilities, and illustrative examples to help you quickly test and deploy your workflows. For details on usage, configuration, and supported features, see readme.

This project contains source code copied and modified from the following third-party project:

• Name: std-uritemplate
• Source: std-uritemplate GitHub Repository
• File Copied: java/src/main/java/io/github/stduritemplate/StdUriTemplate.java
• License: Apache License 2.0
• Copyright: Copyright 2024-2026 std-uritemplate contributors