Nets' Payment Processing Architecture, Built on Event Sourcing

Introduction

Nets is part of Nexi Group, the leading European PayTech company. Nets’ portfolio of products, e-commerce expertise, and industry-specific solutions supports the digital economy and the wider payment ecosystem across channels and payment methods.

Nets operates in three market segments:

• Merchant services and solutions

• Cards and digital payments

• Digital banking and corporate solutions

Nets offers companies solutions that simplify payments and help people and businesses build closer relationships and grow together.

"Overall, the use of event sourcing, Axon Server, and CQRS (Command Query Responsibility Segregation) with tracking event processors have been significant advantages in our development process. These features have enabled us to build highly resilient, scalable, and responsive applications that meet the needs of our business and our customers."

- Tilottama Gulame, Delivery Manager

The Challenge: What Nets Needed From Its Platform

Nets processes payments across merchant services, cards and digital payments, and digital banking for businesses across Europe. When it set out to design a new platform, the bar was high: in financial services, every transaction has to be accounted for, and the system can’t slow down when volume spikes.

1. Auditable and compliant from day one

Regulators expect a complete record of what happened to every payment. Nets needed that audit trail built into the platform, not added later as a separate system to maintain.

2. Scalable under heavy load

Payment volumes rise and fall fast. The platform had to stay responsive at peak without slowing down the rest of the system.

3. Flexible as requirements change

Payments rules and business needs shift constantly. Nets needed to ship new requirements without manual rework, and to deploy on premise, in the cloud, or both as its environment changed.

4. Proven technology

A payments core is no place for experiments. Nets wanted patterns and tools already running in production.

The Solution

When Nets designed its new payment processing architecture, two patterns were a given: CQRS and event sourcing. With Axon Framework providing much of the architecture, Nets' team could focus on business logic.

Event sourcing gives Nets an immutable audit trail out of the box. Every state change is stored as an event, which is exactly what compliance and regulatory reviews in financial services ask for.

Nets' use of CQRS (Command Query Responsibility Segregation) with tracking event processors paid off early. When requirements changed, the team deployed the update and the projections rebuilt themselves without manual work.

CQRS enables Nets to separate its read and write models. This simplifies its architecture, makes it easier to manage and scale its applications, and optimizes the persistence layer for each individual purpose. It simplifies its event processing and ensures that its applications remain responsive and well performing even under heavy loads.

Nets also needed room to move as its environment changed. With Axon Server's flexible deployment topology, Nets deploys its applications on premise, in the cloud, or in a hybrid setup.

Compliance Without a Separate Audit System

In payments, regulators want to know what happened, when, and in what order. Nets didn't bolt an audit log onto its platform. Every state change is stored as an event, so the audit trail is the system of record. The same history lets Nets rebuild projections when requirements change, without touching the underlying data.

The Results

Nets can now adapt to changing business requirements and shifting technology while staying compliant with complex regulatory requirements.

See how Axoniq supports event sourcing for financial services, or how the same approach applies to payment system architecture.