/ Field Notes — series

Enterprise Architecture

Ten editions on the architecture patterns enterprise systems are actually built from — what each one buys, what it costs, and the conditions under which it stops paying.

Editions
10
Written by
Neeraj Kumar
Published
10 of 10
Running
August 27, 2026 — September 9, 2026

Enterprise Architecture Field Notes — the complete series

All ten editions in one document, in series order, with the diagram from each.

Download the field guide
Where do theboundaries go?01LayeredShortcuts becomepermanent architectureboundariesbefore scale02Modular MonolithBoundaries that existonly in the diagrammodularitydistribution later03MicroservicesDistributed cost,weak domain boundariesHow do theparts talk?04Event-DrivenOrdering, duplicates,eventual consistency05Service-OrientedWhere every rulegoes to hideHow does it grow?06MicrokernelA plug-in that reachesinto the core07Space-BasedPartitioning, replication,recovery — all yours08PipelineA chain of mysteriesWhat sitsunderneath AI?09Data PlatformA lake is nota platformtrusted datacomes first10AI & AgentsA prompt is notapplication designEvery pattern relocates complexity rather than removing it. The cost under each is where it goes.
The ten editions as one picture: four questions, and the cost that arrives with each answer. The arrows are the conditions under which moving right is earned — boundaries before scale, modularity before distribution, trusted data before agents. Every card links to its edition.
Edition 1 cover: “Layered Architecture — the foundation of structured systems”. A four-box stack runs presentation, business logic, data access and database, beside short lists of why the pattern matters, what it suits and what to watch for. Neeraj Kumar's portrait and signature appear on the card.

No. 01 Layered Architecture: Start With Clear Boundaries

Architecture gets complicated when boundaries become blurry. Why one of the longest-standing patterns in enterprise software is still one of the most useful — and what goes wrong when its layers become folders rather than decisions.

Edition 2 cover: “Modular Monolith — the disciplined middle ground”. One application box contains order, payment, user and inventory modules above a shared database, beside short lists of why the pattern matters, what it suits and what to watch for. Neeraj Kumar's portrait and signature appear on the card.

No. 02 Modular Monolith: Modularity Before Distribution

Microservices are not the only way to achieve modularity, and for many systems they are not where I would start. What one deployment unit with real internal boundaries buys you — and how that design deteriorates.

Edition 3 cover: “Microservices — independence with operational cost”. APIs, gRPC and messaging feed order, payment, user and inventory services, each with its own database, beside short lists of why the pattern matters, what it suits and what to watch for. Neeraj Kumar's portrait and signature appear on the card.

No. 03 Microservices: Independence Has an Operational Cost

Microservices solve organizational and scaling problems, not fashion problems. The operational responsibilities that arrive with a distributed system, and the question worth asking instead of “should we use microservices?”

Edition 4 cover: “Event-Driven Architecture — react in real time”. An order service publishes to an event bus that fans out to payment, inventory and notification consumers, beside short lists of why the pattern matters, what it suits and what to watch for. Neeraj Kumar's portrait and signature appear on the card.

No. 04 Event-Driven Architecture: React Without Making Everything Wait

Sometimes the fastest way to scale a workflow is to stop making every system wait for every other system. Events do not remove complexity — they relocate it, and the relocation has to be designed.

Edition 5 cover: “Service-Oriented Architecture — enterprise integration before cloud-native”. Mobile, web, ATM, support and branch systems feed an enterprise service bus that routes to customer, payment and account services, beside short lists of why the pattern matters, what it suits and what to watch for. Neeraj Kumar's portrait and signature appear on the card.

No. 05 Service-Oriented Architecture: The Lessons Still Matter

Before microservices became fashionable, enterprises were already trying to solve service boundaries. What SOA got right, what it taught us the hard way, and why dismissing it as old architecture misses the point.

Edition 6 cover: “Microkernel Architecture — keep the core minimal”. A minimal core application sits at the centre with four plug-in features attached by dashed connectors, beside short lists of why the pattern matters, what it suits and what to watch for. Neeraj Kumar's portrait and signature appear on the card.

No. 06 Microkernel Architecture: Keep the Core Small

Keep the core small, then extend capability around it. Why a stable core with disciplined extension contracts lets teams innovate at the edges — and what turns a plug-in ecosystem into version drift.

Edition 7 cover: “Space-Based Architecture — move bottlenecks out of the database”. User, order and payment services feed an in-memory data grid above four processing nodes and a persistent store, beside short lists of why the pattern matters, what it suits and what to watch for. Neeraj Kumar's portrait and signature appear on the card.

No. 07 Space-Based Architecture: When Memory Becomes Part of the Design

At high transaction volumes the database can become the system's shared bottleneck. What it means to move frequently accessed state into a distributed in-memory grid, and the responsibilities that come with it.

Edition 8 cover: “Pipeline Architecture — value is added in stages”. Data input passes through numbered transform, process and finalize stages to an output box above a conveyor belt, beside short lists of why the pattern matters, what it suits and what to watch for. Neeraj Kumar's portrait and signature appear on the card.

No. 08 Pipeline Architecture: Make Every Stage Observable

Complex work becomes easier to manage when it moves through clear stages. The strength of a pipeline is not sequential execution — it is being able to understand and operate the flow.

Edition 9 cover: “Data Platform Architecture — data is the foundation beneath analytics and AI”. Six numbered layers run from sources through ingestion, storage, processing and a semantic layer to consumers, with governance, security and data quality alongside, beside short lists of why the pattern matters, what it suits and what to watch for. Neeraj Kumar's portrait and signature appear on the card.

No. 09 Data Platform Architecture: Storage Is Not the Product

Many AI problems eventually reveal themselves as data problems. Organizations often begin with the model; I usually look underneath it. What separates a data lake from a data platform.

Edition 10 cover: “Architecture for AI & Agents — intelligence needs a real operating model”. A stack runs from user interface through an agent orchestration layer, tools and APIs, a data layer and models to human review, flanked by governance and observability columns, beside short lists of why the pattern matters, what it suits and what to watch for. Neeraj Kumar's portrait and signature appear on the card.

No. 10 Architecture for AI and Agents: Models Are Only One Layer

The model may be the most visible component of an AI system, but it is only one part of the architecture. What changes when agents stop generating text and start taking actions.

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