LangChain4j Workflow 🦜🔀

Build advanced java applications with AI based on flexible stateful workflows 💡

Overview

LangChain4j Workflow is a dynamic, stateful workflow engine crafted as a Java library, drawing inspiration from graph network libraries. It empowers developers with granular control over the flow and state of their applications. This engine is a game-changer for building sophisticated AI applications, such as RAG-based approaches using modern paradigms and agent architectures, where the application's flow and state are pivotal. It enables the crafting of custom behavior, leading to a significant reduction in hallucinations and an increase in response reliability

LangChain4j Workflow is influenced by LangGraph, Graphviz and Apache Beam, and it offers a multitude of benefits. It allows you to define custom workflows as a graph, iteratively, with cycles, flexibility, control, and conditional decisions. These benefits are indispensable for building advanced AI applications.

LangChain4j Workflow is designed to integrate seamlessly with LangChain4j, enabling you to define custom workflows using all the features that LangChain4j offers. This integration could provide a comprehensive toolset for building advanced AI applications.

🌟 Starring me: If you find this repository beneficial, don't forget to give it a star! 🌟 Your support increases its chances of being merged with the LangChain4j codebase. It's a simple way to show your appreciation and help this project grow!

Key Features

• Stateful: LangChain4j Workflow is a stateful engine, enabling you to design custom states as POJO and transitions. This feature provides a robust foundation for managing the flow and state of your application.
• Graph-Based: The workflow is graph-based, offering the flexibility to define custom workflows with multiple directions such as one-way, round trip, cyclic, and more. This feature allows for intricate control over the flow of your application.
• Flexible: LangChain4j Workflow is designed with flexibility in mind. You can define custom workflows and append them at any point in other RAG paradigms, such as Modular RAG. This flexibility allows for a high degree of customization.
• Iterative: The engine supports the implementation of loops and conditionals in your custom workflows. This feature allows for complex logic and flow control within your workflows.
• Streaming Support: LangChain4j Workflow supports streaming outputs as they are produced by each node. This feature allows for real-time processing and response in your application.
• Integration: LangChain4j Workflow is designed to integrate seamlessly with LangChain4j, enabling you to define custom workflows using all the features that LangChain4j offers. This integration provides a comprehensive toolset for building advanced AI applications.
• Visualization: The engine supports the generation of workflow images. This feature allows you to visualize the flow computed of your app workflow. By Default it uses Graphhviz lib to generate the image, but you implement your own image generator on GraphImageGenerator.java interface.

Installation

mvn clean package install

Example

In LangChain4j Workflow, the notion of state plays a pivotal role. Every execution of the graph initiates a state, which is then transferred among the nodes during their execution. Each node, after its execution, updates this internal state with its own return value. The method by which the graph updates its internal state is determined by user-defined functions.

Add the following dependency to your pom.xml file:

<dependency>
  <groupId>dev.langchain4j</groupId>
  <artifactId>langchain4j-workflow</artifactId>
  <version>0.1.0</version> <!--Change to the latest version-->
</dependency>

Define a stateful bean with fields that will be used to store the state of the workflow:

// Define a stateful bean
public class MyStatefulBean {
  int value = 0;
}

Create a simple workflow with 4 nodes and conditional edges:

public class Example {
  public static void main(String[] args) {
    
    MyStatefulBean myStatefulBean = new MyStatefulBean();

    // Define functions that determines statefulBean state
    Function<MyStatefulBean, String> node1Func = obj -> {
      obj.value +=1;
      System.out.println("Node 1: [" + obj.value + "]");
      return "Node1: function proceed";
    };
    Function<MyStatefulBean, String> node2Func = obj -> {
      obj.value +=2;
      System.out.println("Node 2: [" + obj.value + "]");
      return "Node2: function proceed";
    };
    Function<MyStatefulBean, String> node3Func = obj -> {
      obj.value +=3;
      System.out.println("Node 3: [" + obj.value + "]");
      return "Node3: function proceed";
    };
    Function<MyStatefulBean, String> node4Func = obj -> {
      obj.value +=4;
      System.out.println("Node 4: [" + obj.value + "]");
      return "Node4: function proceed";
    };

    // Create the nodes and associate them with the functions to be used during execution.
    Node<MyStatefulBean, String> node1 = Node.from("node1", node1Func);
    Node<MyStatefulBean, String> node2 = Node.from("node2", node2Func);
    Node<MyStatefulBean, String> node3 = Node.from("node3", node3Func);
    Node<MyStatefulBean, String> node4 = Node.from("node4", node4Func);


    // Create workflow
    StateWorkflow<MyStatefulBean> workflow = DefaultStateWorkflow.<MyStatefulBean>builder() 
            .statefulBean(myStatefulBean)
            .addNodes(Arrays.asList(node1, node2, node3))
            .build();

    // You can add more nodes after workflow build. E.g. node4
    workflow.addNode(node4);

    // Define edges
    workflow.putEdge(node1, node2);
    workflow.putEdge(node2, node3);
    // Conditional edge
    workflow.putEdge(node3, Conditional.eval(obj -> {
      System.out.println("Stateful Value [" + obj.value + "]");
      if (obj.value > 6) {
        return node4;
      } else {
        return node2;
      }
    }));
    workflow.putEdge(node4, WorkflowStateName.END);

    // Define which node to start
    workflow.startNode(node1);

    // Run workflow normally
    workflow.run();
    // OR
    // Run workflow in streaming mode
    workflow.runStream(node -> {
      System.out.println("Processing node: " + node.getName());
    });

    // Print all computed transitions
    String transitions = workflow.prettyTransitions();
    System.out.println("Transitions: \n");
    System.out.println(transitions);

    // Generate workflow image
    workflow.generateWorkflowImage("image/my-workflow.svg");
    // workflow.generateWorkflowImage(); // if you use this method, it'll use by default the root path and default image name.
  }
}

Now you can check the output of the workflow execution.

STARTING workflow in stream mode..
Processing node: node1
Node 1: [1]
Processing node: node2
Node 2: [3]
Processing node: node3
Node 3: [6]
Stateful Value [6]
Processing node: node2
Node 2: [8]
Processing node: node3
Node 3: [11]
Stateful Value [11]
Processing node: node4
Node 4: [15]
Reached END state

You can print all computed transitions:

START -> node1 -> node2 -> node3 -> node2 -> node3 -> node4 -> END

You can generate a workflow image with all computed transitions:

LLM examples

You can check all examples in the langchain4j-worflow-examples repository. Please note that examples can be modified and more examples will be added over time.

MoA

• Mixture-of-Agents (MoA):
  • Java example: langchain4j-moa
  • Based on Paper: https://arxiv.org/pdf/2406.04692

RAG

• Corrective RAG (CRAG):
  • Java example: langchain4j-corrective-rag
  • Based on Paper: https://arxiv.org/pdf/2401.15884
• Adaptive RAG:
  • Java example: Very soon
  • Based on Paper: https://arxiv.org/pdf/2403.14403
• Self RAG:
  • Java example: Very soon
  • Based on Paper: https://arxiv.org/pdf/2310.11511
• Modular RAG:
  • Java example: Very soon
  • Based on Paper: https://arxiv.org/pdf/2312.10997v1

Agent Architectures

• Multi-agent Collaboration:
  • Java example: Very soon
  • Based on Paper: https://arxiv.org/pdf/2308.08155
• Agent Supervisor:
  • Java example: Very soon
  • Based on Paper: https://arxiv.org/pdf/2308.08155
• Planning Agents:
  • Java example: Very soon
  • Based on Paper: https://arxiv.org/pdf/2305.04091

Contribute & feedback

If you have any feedback, suggestions, or want to contribute, please feel free to open an issue or a pull request. We are open to new ideas and suggestions. Help us to maturity this project and make it more useful for the community in order to merge it with LangChain4j source code.

Authors

• Carlos Zela @c_zela