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Batch vs. Event-Driven Architecture

A postal worker runs the scheduled mail route and the rush courier desk out of the same office, showing when to batch data on a schedule and when to react to it the instant it happens.

Part 1

Batch vs. Event-Driven: The Scheduled Mail Route and the Rush Courier

the fundamental choice between processing data on a schedule and processing it the instant it happens, and why almost every data system ends up choosing one or blending both.

Part 2

Why Batch Processing Still Makes Sense for a Lot of Mail

why collecting data and processing it together, on a schedule, remains the right answer for a large share of real workloads.

Part 3

The Case for Event-Driven: When Waiting for the Next Round Isn't Good Enough

the workloads where processing data the instant it happens isn't a nice-to-have, but the entire point.

Part 4

Throughput vs. Latency: One Full Truck vs. One Courier Per Letter

why processing everything together is more efficient per record, while processing one thing at a time is faster per record, and why you can rarely maximize both at once.

Part 5

The Dispatch Desk: Message Queues and Brokers Explained

how the component that matches a ready package to an available courier maps directly onto message queues and brokers in an event-driven system.

Part 6

Idempotency: Making Sure a Package Isn't Delivered Twice

why event-driven systems need a way to safely retry a delivery without accidentally processing the same thing more than once.

Part 7

Backpressure: Telling the Couriers to Slow Down

how a dispatch desk protects an event-driven system from collapse when packages arrive faster than couriers can handle them.

Part 8

Lambda Architecture: Running the Scheduled Route and the Courier Desk Together

how running a batch route and a courier desk out of the same post office maps onto lambda architecture, and why it exists at all.

Part 9

Kappa Architecture: Retiring the Scheduled Route Entirely

why some post offices eventually drop the scheduled truck altogether and run everything through the courier desk instead.

Part 10

Choosing Batch Windows: How Often Should the Truck Actually Leave?

how a post office decides between an hourly, daily, or weekly truck schedule, and how that maps onto choosing a batch interval.

Part 11

Event Ordering: Making Sure Packages Arrive in the Right Sequence

why an address-change notice arriving after the package it was meant to redirect causes real problems, and how event-driven systems guard against it.

Part 12

Exactly-Once vs. At-Least-Once Delivery Guarantees

the honest promise a postal service can actually make about delivery, and why most systems settle for at-least-once plus idempotency instead of true exactly-once.

Part 13

Monitoring an Event-Driven System: Watching Every Courier at Once

why a postmaster tracking a hundred independent couriers needs a fundamentally different kind of dashboard than one tracking a single nightly truck.

Part 14

Cost Trade-Offs: A Full Truck Route vs. a Fleet of On-Call Couriers

the honest financial comparison between running one scheduled truck route and keeping a fleet of couriers ready around the clock.

Part 15

Migrating From Batch to Event-Driven Without Breaking the Mail Room

how a post office moves from a truck route to a courier system without losing a single piece of mail along the way.

Part 16

Event-Driven Architecture for AI Agents: Couriers Triggered by a Model's Decision

what changes when the thing dispatching the courier isn't a human at the counter, but a model deciding on its own that something needs to move.

Part 17

Testing Event-Driven Systems: Simulating a Day of Unpredictable Packages

how a post office rehearses for chaos before it actually happens, and what that looks like for an event-driven system's test suite.

Part 18

When Event-Driven Architecture Is Overkill for the Job

why a small post office running one street doesn't need a dispatch desk, a broker, and a fleet of on-call couriers just to deliver the mail.

Part 19

Common Batch and Event-Driven Failures (and Mail That Never Arrived)

the recurring, specific ways a scheduled route and a courier system each tend to fail, and what an honest failure catalogue looks like for both.

Part 20

The Future: A Postal System That Chooses Its Own Delivery Method

what it might look like for a post office to decide, package by package, whether something belongs on the truck or with a courier, without a human making that call.