Distributed System Architecture: Modern Three-Tier

Modern Three-Tier

The most used infrastructure architecture for SMEs and data-oriented small businesses operating on a global scale.

When it comes to the technology stack, and if talking about Web Applications then the most common setup I have seen all over the place is React.js being used for SPA or PWA frontend as a client/presentation layer, node.js as a Rest API Server/business layer and Cassandra (open source) as distributed (optionally cloud-based), fault-tolerant, well-performed, durable, elastic, …, supported (don’t forget on decent support from the community!), decentralized and scalable database/persistent layer.

Your database does not have to tick all of these boxes from above (apart from being distributed), but if you’re going to put all that effort to build this type of infrastructure, you want to make sure that the database meets as many required features from being modern and long-lasting solution sitting in infrastructure as possible (think about your development ROI Devs!!).

The way how it works is that the client application (fetched from the store or application server) is capable to handle the user tasks by itself on the client device with the data supported over the API (node.js) and in event of Server API running out of the breath, a new instance of the Application API server will be provisioned (new node is getting created, horizontal scaling -> scaling out/in).

Database, as it stands in this model, does not have this scaling capability but can scale up or down instead as needed (service is given more system resources, vertical scaling -> scaling up/down).

An illustration of how it’s getting all wired up together

1.1 Modern 3-Tier Distributed System Architecture



  • great logical separation and isolation with a lot of room for cybersecurity policy integration
  • not-complex architecture when it comes to problem investigation and troubleshooting
  • easy to medium complexity to get the infrastructure up and ready for development and maintenance (less DevOps, yaay!)
  • an easy option to replicate infrastructure on user localhost for development purposes (just makes it all easier during branch development)
  • infrastructure running cost is relatively small


  • decommissioning provisioned nodes can be tricky (depends on the technology used)
  • data synchronization and access need orchestration (subjected to database type)
  • shipping new features out need an entire Application server deployment (downtime)

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