Design and Architecture of Payment Systems: Product Classification, Module Functions, and Business Flow

In internet product operations, rising traffic costs and declining user activity drive the need for integrated payment systems that close the commercial loop.

Payment products are classified into ten types such as Quick Pay, Online Banking, Protocol Pay, Platform Pay, Foreign Card Pay, Phone‑Bill Pay, Virtual Currency Pay, Account Pay, Credit Pay, and Agency Pay, each serving different scenarios.

The payment module sits between the payment gateway and the payment channels, exposing a unified interface and acting as a proxy micro‑service that routes requests to the appropriate channel.

Overall module functions include contract signing/termination, payment execution, revocation/refund, contract and order status queries, pre‑authorization workflows, reconciliation, and balance queries.

The typical business flow comprises parameter validation, payment routing, risk assessment, order generation, channel invocation, order update, message notification, and asynchronous callbacks.

Typical architecture consists of a support layer (monitoring, logging, SMS, security, reporting), a core layer (payment core and service modules), and a product layer that delivers services to users, merchants, and operators.

Reference implementations from major internet companies (Alipay, JD Finance, Qunar, Meituan) illustrate real‑world designs, including accounting separation, flexible transaction handling, and compliance considerations.

Overall, a payment system integrates supporting infrastructure, core processing, and service subsystems to provide reliable, secure, and scalable payment capabilities.