Integrating Python Machine Learning Models into Spring Boot Applications

What will you learn?

In this comprehensive guide, you will learn how to seamlessly integrate Python machine learning models into Spring Boot applications. Discover the power of combining Python’s machine learning libraries with Java’s robust Spring Boot framework to enhance your projects.

Introduction to the Problem and Solution

When developing modern web applications that require complex computations or predictions, integrating machine learning models becomes crucial. Often, data science teams develop models in Python using libraries like TensorFlow or scikit-learn, while back-end systems are constructed with Java frameworks such as Spring Boot for their scalability and reliability. This presents a unique challenge of bridging these two distinct worlds effectively.

The solution lies in adopting a microservice architecture where the Python model functions as an independent service that communicates with our Spring Boot application. This approach not only allows us to capitalize on the strengths of both languages but also ensures modularity and scalability of our application. We will guide you through setting up a simple Flask server for the Python model and demonstrate how to call this service from a Spring Boot application using REST templates.


# Flask app serving the ML model (
from flask import Flask, request, jsonify
import pickle

app = Flask(__name__)

# Load your trained model
model = pickle.load(open('model.pkl', 'rb'))

@app.route('/predict', methods=['POST'])
def predict():
    data = request.get_json()
    prediction = model.predict([data['features']])
    return jsonify({'prediction': str(prediction)})

if __name__ == '__main__':

# Copyright PHD
// Spring Boot service calling the ML model
import org.springframework.web.client.RestTemplate;
import org.springframework.http.*;

public class PredictionService {

    public String getPrediction(float[] features) {
        final String uri = "http://localhost:5000/predict";

        // Prepare request body
        HttpHeaders headers = new HttpHeaders();
        JSONObject requestBody = new JSONObject();
        requestBody.put("features", features);

        // Make POST request and receive response 
        HttpEntity<String> entity = new HttpEntity<>(requestBody.toString(), headers);

        RestTemplate restTemplate = new RestTemplate();
        ResponseEntity<String> result = restTemplate.postForEntity(uri, entity, String.class);

        return result.getBody();

# Copyright PHD


The solution comprises two main components:

  1. Python Flask Application: A lightweight Flask server is established to serve the pre-trained machine learning model. The server exposes an endpoint (/predict) that accepts JSON payloads via POST requests containing input features for prediction.

  2. Spring Boot Service: On the other end, we have our primary backend system developed with Spring Boot that needs to utilize predictions from our ML model. To facilitate this interaction, we employ RestTemplate within a dedicated service class PredictionService in our Java codebase to make HTTP POST requests to the Flask server while passing necessary input features in JSON format.

This setup ensures loose coupling between your machine learning models and web application logic, enabling seamless updates or replacements without disrupting other services.

    What is microservice architecture?

    Microservice architecture is a design paradigm where applications are composed of small, independently deployable services running unique processes and communicating through lightweight protocols.

    Can I use another framework instead of Flask?

    Certainly! While Flask is chosen here for its simplicity and ease-of-use for demonstration purposes, you have the flexibility to opt for any other web framework like Django or FastAPI based on your specific requirements.

    Why do we serialize the model with pickle?

    Serialization using pickle converts the Python object (in this case, our trained ML model) into a byte stream that can be stored on disk, allowing direct loading without retraining when needed.

    Is RestTemplate synchronous?

    Yes, RestTemplate performs synchronous HTTP requests by blocking execution until it receives responses from called API endpoints, making it suitable for straightforward backend-to-backend communication scenarios like ours.

    How can I secure communication between services?

    Securing inter-service communication involves various strategies such as implementing HTTPS protocols with SSL/TLS certificates and utilizing authentication mechanisms like OAuth tokens or API keys based on sensitivity levels involved.


    Integrating Python machine learning models into Java-based architectures such as those built with Spring Boot presents exciting opportunities to enhance applications with intelligent capabilities while maintaining modularity and manageability. By leveraging tools like Flask alongside structured approaches in handling HTTP communications via RestTemplate, developers can create resilient systems that leverage top-notch functionalities across different technology stacks.

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