Event Catalog: The Tool To Optimize Your Event-Driven Architecture

What is an event catalog

“Event catalog” is an umbrella term that encompasses the functionalities of the schema registry (repository), schema registry API, and the documentation site. It refers to a centralized repository that lists or documents events that can occur within a software system. These events often correspond to specific actions, triggers, or occurrences that the developers must be aware of and respond to.

Event catalogs illuminate the event landscape, simplifying discovery, ensuring consistency, and empowering developers and data analysts; all of this serves to provide additional context to events subscribed to. They are designed to help you document and capture your events, owners, versions, producers, consumers, services, domains, schemas, code examples, and much more. With these event details, you can outline the event’s meaning and suggest investigation, troubleshooting, and likely causes.

Just as data catalogs guide us through data oceans, event catalogs map the intricate pathways of events, enabling ease of use, developer experience, and managing maintenance overhead in an event-driven architecture (EDA).

Key concepts of event catalog

Event cataloging involves several key concepts that are fundamental to understanding and implementing event-driven architectures.

• Custom events: Custom events are significant state changes within a software system. User actions, system processes, external integrations, or other sources can trigger events.
• Service: Services are simply applications that produce or consume events. Services are often assigned an owner and optionally have OpenAPI or AsyncAPI specifications attached.
• Domain: Domains serve as clusters of events and services. They aim to establish clear, high-level boundaries, providing organization to your system. Typically, each domain is assigned a dedicated owner for effective management.
• Event attributes: Another fundamental concept of the event catalog is event attributes. Defining attributes that effectively describe the event in terms of quantity and quality is essential. These attributes specify the name, value, event code, channel, and data type of an event, significantly enhancing the value of the event notification.

Event catalogs are essential in an event-driven system, where components often communicate through events. To get a broader picture of how event catalogs come into play, let’s explore what it means to be event-driven.

What does it mean to be event-driven?

Events are updates or changes in state that occur within or outside an organization that can be detected, recorded, and subsequently communicated. Therefore, an event can be any action within or to a system — like customer purchases, inventory updates, security breaches, or application state changes.

Hence, to be event-driven means being guided by actions or changes in the state of an environment. Instead of proactively initiating tasks, an event-driven system waits for specific occurrences (events) to happen and then reacts accordingly. Think of it like a driver responding to their environment while in traffic: hitting the brakes for a red light, turning the wheel for a curve, and accelerating at a green light.

Events are characterized by their immutable nature, serving as a permanent record of occurrences with an indefinite lifespan that can be processed at any time. In an EDA, an event is likely to result in one or more actions or processes upon its occurrence.

Benefits of event catalogs

Documentation and managing the sheer volume and variety of events in EDAs present immense challenges: discovering crucial events, untangling their intricate flow, and ensuring data quality. However, an event catalog offers several benefits that address these challenges; they include:

• Creating a centralized repository that documents services and schemas.
• Describing events using key attributes and providing a detailed history of these events.
• Offering a comprehensive insight for teams to communicate and visualize event definition, payload schemas, and other service dependencies.
• Enabling the grouping of services and events by domain.
• Designing interactive user interfaces for producers and consumers to explore our events, bounded contexts, and more.
• Improving the developer experience by helping teams address the issues directly and thus reduce any impacts on your environment.

How Netflix and Zalando achieved increased profitability and developer experience with EDA

EDA offers several use cases, including fraud detection, end-to-end updates, the Internet of Things (IoT), website monitoring, payment processing, and real-time marketing. Businesses invest in EDA primarily for its real-time capabilities, which enable organizations to respond swiftly and efficiently to dynamic market demands. They also do so to benefit from its decoupled nature, which provides the flexibility to navigate and manage unforeseen disruptions.

In recent years, several renowned organizations have embraced EDA in their applications. For instance, Netflix experienced several business concerns and challenges tracking spending, programming catalogs, and producing financial reports. They built a microservices architecture powered by event streams to address these crucial business logic concerns. These microservices, like recommendation engines and content delivery networks, communicated through events, ensuring real-time personalization and content delivery optimization. Netflix embraced Apache Kafka® as the de-facto standard for eventing, messaging, and stream processing. This introduced a highly scalable and fault-tolerant platform that can quickly adapt to changing user behavior and content offerings.

Another example of success with EDAs is the case of Zalando, a leading online fashion retailer whose architecture centers around decoupled microservices. They manage a highly complex system with numerous microservices interacting through events for order processing, inventory updates, and personalized recommendations. By leveraging asynchronous event-driven approaches, Zalando implemented an event catalog to provide a single source of truth for all event definitions, including schemas, producers, consumers, and associated documentation. This improved the developer experience, enabling easy discovery and understanding of available events. It also reduced errors and inconsistencies in event usage.

Overall, event catalogs are vital in achieving success within organizations relying on EDAs. They empower developers to observe and monitor event flows, thereby optimizing efficiency and scalability and fostering flexibility, agility, and enhanced operational performance.

Leveraging the power of event catalogs

The Digital Integration Hub (DIH) acts as a high-performance, low-latency, and scale-out data store that is synchronized with the backend sources via some combination of event-based, request-based, and batch integration patterns. DIHs manage events and data in a multifaceted way, primarily focusing on EDA and real-time processing. It taps into the capabilities of the event catalog by decoupling the layer between back‑end systems and front‑end services. It facilitates extensive API-based access to applications and data in a system of record, ensuring minimal impact on system workload. Additionally, it adds value through analytics capabilities.

Mia‑Platform serves as the ready-to-use enabler for the Digital Integration Hub. It facilitates the construction of a Digital Integration Hub using Mia‑Platform Fast Data. This tool guarantees an EDA that collects data from any existing system and organizes it according to your business needs — while improving the overall developer experience.

Wrapping up

EDA enables real-time communications between systems and services across environments and geographies, including security branch transactions, lending systems, e-commerce sites, payment systems, account data, etc. However, it also introduces some new difficulties and complexities, which can be tackled through proper event cataloging. It’s important to note that EDA adoption is not a one-size-fits-all approach. Each organization should customize its implementation to meet specific needs and challenges.

With Mia-Platform’s products, you will be able to create your own comprehensive event platform calibrated to your specific business needs. Watch this video demo to see how to create one in less than 10 minutes!