Using stream processing to power real-time machine learning (ML) can create dynamic and responsive systems capable of making intelligent decisions in real time. Stream processing deals with the continuous and rapid analysis of data as it flows in, enabling organizations to harness data as it's generated. On the other hand, machine learning involves training models on historical data to make predictions or classifications on new data. Traditionally, ML has been used in batch processing scenarios, but its application in real-time scenarios is becoming increasingly important for applications like fraud detection, recommendation systems, and internet of things (IoT) analytics.

This article explores the intersection of stream processing and real-time machine learning. It begins by introducing the concept and highlighting the importance of stream processing in the realm of real-time ML. By the end of the article, you'll have a solid understanding of the synergy between stream processing and real-time ML.

The Need for Stream Processing

At its core, stream processing involves the real-time analysis and manipulation of data as it flows in, allowing organizations to keep pace with the rapid influx of high-velocity data streams. This capability is vital in an era where data is generated at an unprecedented rate from sources like sensors, social media, IoT devices, and so on.

Real-time data ingestion is one key advantage of stream processing. Unlike traditional batch processing, which works with data in chunks, stream processing ingests and analyzes data point by point as it's produced. This real-time ingestion allows businesses to respond instantly to changing conditions. For example, an e-commerce platform can process user interactions as they happen, immediately tailoring product recommendations or promotional offers based on the user's current behavior. This level of responsiveness can significantly enhance the user experience and drive engagement.

Scalability is another compelling reason to embrace stream processing. As data volumes grow, stream processing systems can effortlessly scale to handle the increased load. Whether you have a sudden surge in data or a consistently high data volume, stream processing frameworks like Apache Kafka, Apache Flink, or RisingWave can distribute the workload across multiple nodes, ensuring efficient processing without compromising performance. This scalability is crucial for businesses that need to adapt to changing demands and handle large-scale data processing tasks without incurring exorbitant infrastructure costs.

Moreover, stream processing offers cost efficiency by optimizing resource utilization and allowing you to pay only for the resources you need, precisely when you need them. Additionally, real-time applications rely on the high availability of services. Stream processing supports better fault tolerance in these applications by allowing systems to continue processing even when there are hardware failures on certain nodes or other issues. This ensures uninterrupted data analysis and minimizes downtime.

Why Is Stream Processing Crucial in the Machine Learning Lifecycle?

The significance of stream processing extends far beyond traditional applications. This section explores why stream processing is crucial in the ML lifecycle, shedding light on its role in enhancing the performance and usability of various ML applications. For illustrative purposes, the article focuses on the dynamic and data-intensive world of over-the-top (OTT) platforms, such as Netflix, Amazon Prime Video, and Disney+.

Traditional ML pipeline

Before getting into the details of stream processing in the ML lifecycle, it helps to familiarize yourself with the typical workflow for training and using ML models in the industry. The following diagram illustrates a traditional machine learning pipeline:

Featured A traditional machine learning pipeline.

The process begins with the initial source data, which is meticulously transformed to make it suitable for model training. The model training engine leverages algorithms and mathematical techniques to learn patterns and relationships within the data. Through this process, it generates "model artifacts," which essentially hold the distilled knowledge that the model has acquired from the training data. They are then securely stored for future use to make predictions. The ML models need to be retrained to ensure they remain up-to-date with new data. This step is crucial, as models can become outdated as new information becomes available.

This seamless flow, from data preparation and model training to inference and then retraining of models, is repeated as a continuous cycle. It's important to note that in this conventional approach, the model is retrained by combining the new and old data each time the cycle repeats, rather than incrementally.

Importance of Stream Processing in ML Applications

Now that you have an understanding of a traditional ML pipeline, let's use the following example to understand why stream processing is crucial in the ML lifecycle.

Recent years have seen the rise of OTT applications, with vast numbers of viewers embracing streaming content alongside or even in place of regular satellite providers. The limitations of batch ML quickly become evident in such user-facing apps when stream processing is not integrated into the ML application lifecycle.

Imagine you've been watching several movies in the crime genre lately. So, when you log in to your OTT app, you should see a list of recommended crime movies in your profile. However, today you decide to watch some family dramas instead and search for the "drama" category. Ideally, the OTT app should recognize this change and update your recommendations with more drama movies. But, without real-time streaming data feeding into the ML model, the app cannot refresh the recommendation list with the latest drama genre selections. If the app can only use batch ML operations, you'll continue to get recommendations based on the crime genre until the next batch operation cycle completes.

Enabling Continuous Learning Based on Streaming Data

The example in the previous section demonstrated how important stream processing is for ML operations. This section focuses on how to enable the trained model to continually learn from streaming data. The following diagram illustrates how this process works:

Featured Real-time ML pipeline.

Real-time machine learning pipelines require a dynamic and responsive approach to model training and inference. The process starts with an initial model training phase with an optional batch mode or streaming mode, and this is based on the volume of data available for the use case. If the machine learning use case has a significant number of historical datasets, then a traditional bulk data processing and model building pipeline is suitable. Otherwise, the stream-based processing pipeline can be chosen to process the records one by one or in smaller chunks as they arrive in streams.

The data in general has to undergo meticulous preparation to ensure its suitability for model training. The model training engine leverages advanced algorithms to learn from the data, culminating in the generation of valuable model artifacts. These artifacts, representing the distilled knowledge of the model, are securely stored for future use. When real-time inference is required, the inference engine retrieves the latest published model and serves inference results to designated targets such as users, systems, or devices. This initial model setup lays the groundwork for a flexible and adaptive real-time ML pipeline.

However, the true power of this pipeline lies in its ability to continuously evolve and adapt. Model retraining takes on a real-time stream processing mode where new data streams into the system. In this phase, stream processors and transformers come into play, performing tasks like drift identification and data preparation for model training. The model training engine here takes a more granular approach, allowing training based on each incoming record or incremental records, ensuring that the model remains up-to-date and responsive to changing data patterns. Like in the initial training phase, this process results in the creation of updated model artifacts, which are stored for future use.

The inference engine plays a pivotal role throughout this dynamic cycle, retrieving the latest published model to deliver real-time inferences to the designated targets. This continuous evolution, from initial batch training to real-time stream processing, ensures that the machine learning models stay relevant and accurate. Real-time ML pipelines like these empower organizations to harness the full potential of their data and make timely, informed decisions.

Additional Stream Processing and Real-Time Machine Learning Use Cases

Integrating stream processing with machine learning applications brings forth a range of significant benefits that can transform how organizations leverage data. Here are some key advantages, along with examples to illustrate the impact:

  • Fraud detection and prevention: ML models that utilize stream processing can continuously analyze transaction data from various sources in real time. ML models can identify patterns of fraudulent activity. For instance, if a transaction occurs in an unusual pattern, the system can trigger an alert to help you immediately take preventive action. This can prevent financial loss and safeguard users in real time.
  • Anomaly detection: ML models that utilize stream processing can continuously analyze network traffic data. ML models can learn what constitutes "normal" behavior and raise alerts when anomalies or security threats are detected. This proactive approach helps mitigate cybersecurity risks.
  • Dynamic pricing: E-commerce companies can adjust prices in real time based on factors like demand, competition, and inventory levels. Stream processing can gather user actions and process market data while ML models predict optimal pricing strategies based on these influencing features. This dynamic pricing approach maximizes revenue and ensures competitiveness.


This article explored the potential of integrating stream processing and ML for more dynamic, intelligent, and responsive applications. You learned about the advantages of stream processing, including real-time data ingestion, scalability, cost efficiency, and fault tolerance. Moreover, you explored the pivotal role of stream processing in the ML lifecycle, illustrated through use cases such as fraud detection, recommendation systems, dynamic pricing, and anomaly detection.

If you want to create real-time ML pipelines, you need a robust, flexible, and reliable stream processing platform. RisingWave is a distributed SQL database specifically designed to streamline the process of building real-time applications. RisingWave simplifies development, reduces costs, and seamlessly processes streaming data, enabling continuous real-time updates—a critical feature in ML workflows.

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