Adopting an event driven architecture

As modern microservices-based architectures continue to evolve, event-driven architecture is becoming increasingly popular. It offers a flexible and responsive approach to business events while fostering better technical decoupling.

An event-driven architecture uses events to initiate and communicate between decoupled services, typically built with microservices. An event represents a fact, a change in state, or an update that has occurred in the past, such as an item being placed in a shopping cart on an e-commerce website. This architecture logs the stream of events, facilitating real-time user interactions, pluggable microservices, and data analytics.

Some examples of event-driven architecture tools and platforms include SOLACE, which helps transition from batch processes to event processes, and Kafka, a data-focused streaming platform that handles messaging in streams.

Key design principles of event-driven architecture include:

1. Message-driven: Asynchronous messaging enables efficient communication between services.
2. Scalability: The architecture supports growth and adapts to changes in demand.
3. Resiliency: A distributed system eliminates single points of failure and is fault-tolerant.
4. Maintainability: The architecture is easy to update, fix, and modify.
5. Extensibility: The system can be expanded easily to accommodate new requirements.

To better illustrate the concept, let’s explore two case studies:

Case Study 1: In a retail application, the checkout service communicates with inventory, shipping, and contact services through messaging. When the checkout service produces an event, it doesn’t care which services consume it, resulting in a highly scalable system with data persistence and a permanent record of all checkouts.

Case Study 2: Another retail example involves the checkout service sending messages to the inventory service, which consumes data from the stream and updates the inventory position for all consuming services. This data can be stored in a data lake accessible by all services.

In these cases, web applications, mobile applications, and even edge devices produce events for the system. Event logs created by these applications can trigger actions for IoT devices and serverless functions (FaaS). Once IoT devices complete their tasks, they send another message.

Key features of event-driven architecture include:

1. Stream Processing: Normally built on top of Apache Kafka (see below), this feature allows for real-time data processing. For example, a music streaming service can provide personalized 
2. Communication Layer: A PUB/SUB communication layer enables containerized microservices to consume or subscribe to any services in a pluggable manner. This approach allows consumption from any point in the past or present.

Apache Kafka: Modern-day cloud applications often rely on Kafka for real-time experiences. Developers can create applications that simultaneously produce and consume streams of data records. These records are replicated and partitioned, ensuring high performance, resiliency, fault tolerance, accuracy, and proper order of occurrence. Kafka decouples system dependencies, eliminating hard integrations. Instead, services subscribe to events, triggering actions as needed.

At XOOTS, we consider event-driven architecture as a powerful and versatile approach to building modern, scalable, and resilient systems. By adopting this architecture, businesses can better adapt to changing requirements and improve their overall responsiveness.