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126 questions, 454 terms and 400 topics in 20 areas.
60 results for “Modernisation Business Case”
Booking.com's Experimentation Platform
Booking.com runs over a thousand concurrent experiments and treats the ability to test any change safely as a platform capability rather than a product feature.
Spotify's Squad Model and Its Retrospective
The widely-copied Spotify model of squads, tribes, chapters and guilds was a snapshot that did not work as documented even at Spotify — a caution about importing organisational design.
Business Capability
What a business does, expressed stably and independently of how it currently does it or who is responsible.
Airbnb's Service-Oriented Migration
Airbnb decomposed a large Rails monolith by first extracting a unified data-access layer, so that services were built on owned data rather than on shared database tables.
Application Portfolio Management
Maintaining an inventory of every application with its owner, cost, business value and technical health, and using it to decide what to invest in, replace or retire.
Capability Map
A structured view of everything a business does, used as the stable frame for mapping applications, investment, ownership and gaps.
Capital One's Data Centre Exit
A major US bank closed all eight of its data centres and moved fully to public cloud, treating governance automation as the enabling technology rather than a constraint.
Compensating Transaction
A business operation that semantically undoes a previously committed step — not a rollback, because the original effect was visible and may not be fully reversible.
Discord's Message Store Migrations
Discord moved from MongoDB to Cassandra to ScyllaDB as message volume grew from millions to trillions, each time for a specific and different reason.
Domain-Driven Design
Modelling software around the business domain, with boundaries drawn where the language of the business changes.
Dropbox's Move Off S3
Dropbox moved the majority of its file storage off Amazon S3 onto custom infrastructure, reporting savings that its S-1 filing put at roughly $75 million over two years.
Etsy's Continuous Deployment
Etsy moved from infrequent, risky releases to dozens of deploys a day, demonstrating that deployment frequency and stability improve together rather than trading off.
Figma's Postgres Sharding
Figma delayed sharding for years using replicas and vertical partitioning, then sharded Postgres horizontally without downtime using logical shards and a proxy layer.
Google Maps and Planetary-Scale Spatial Serving
Map serving is fast because almost nothing is computed on request — the world is precomputed into a pyramid of tiles, and space is indexed onto a one-dimensional curve.
Instagram's Early Scaling
Instagram reached tens of millions of users on Django and PostgreSQL with a handful of engineers, by deliberately choosing boring technology and doing the simple thing first.
LinkedIn and the Origin of Kafka
Kafka was built to replace point-to-point data integration between many systems with a single durable log that any system could publish to and any number could read.
Microservices
An architectural style where an application is a set of independently deployable services, each owning its data and aligned to a business capability.
Monzo's Microservice Estate
Monzo runs a bank on well over a thousand microservices, and the interesting engineering is in the platform and network isolation that makes that number survivable.
Netflix Open Connect
Netflix built its own CDN and placed appliances inside ISP networks, turning the most expensive part of its cost structure into hardware it controls.
Netflix's Recommendation Architecture
Netflix splits personalisation into offline, nearline and online layers so that expensive computation happens ahead of time and the request path stays fast.
Outbox Pattern
Writing an outgoing message into a table in the same transaction as the business change, and relaying it to the broker separately, so the two cannot diverge.
PACELC
An extension of CAP that also describes the normal case — if Partitioned choose Availability or Consistency, Else choose Latency or Consistency.
Southwest cancelled about 16,700 flights in December 2022 when crew scheduling could not recover from a storm, after years of deferred modernisation. How do you make that argument before the failure rather than after?
The case, as publicly reported A severe winter storm caused widespread cancellations across US carriers. Most recovered within days; Southwest did not. Its crew
A 15-year-old monolith runs the core of the business. Leadership wants microservices. How do you approach it, and what would make you refuse?
What the interviewer is testing Whether you start from the business problem or from the target architecture, and whether you are willing to say no. First, estab
A team wants to build a new internal API on serverless functions. It will serve steady traffic of about 200 requests per second during business hours. What do you advise?
What the interviewer is testing Whether you can apply the serverless trade off to a specific workload rather than treating it as a default good or a default bad
Security wants mandatory hardware keys for every login; the business says it will cost conversions. How do you resolve it architecturally rather than by picking a side?
What the interviewer is testing Whether you treat security as a fixed dial to be turned up, or as a risk proportionate design variable. Both stated positions ar
The business asks for "100% uptime" for a new customer portal. Walk me through the conversation that ends in an agreed SLO.
What the interviewer is testing Whether you can run a negotiation that ends in a number both sides own, rather than either capitulating or lecturing about nines
The business asks for "multi-region" after a regional outage. Before agreeing, what do you need to establish, and what are you actually signing up for?
What the interviewer is testing Whether you convert a vague requirement into numbers before designing, and whether you know that multi region is primarily a dat
A 43-second network partition caused GitHub over 24 hours of degraded service in 2018. How does a 43-second event become a day-long incident?
The case, as publicly reported On 21 October 2018, routine maintenance replacing failing optical equipment caused a 43 second loss of connectivity between GitHu
A startup asks you to architect their product "to handle millions of users". They currently have none. What do you actually build?
What the interviewer is testing Whether you can identify the real constraint. The stated requirement is scale; the actual constraint is survival, and an archite
Discord stores trillions of messages. What is their partition key, and what problem does the second half of it solve?
The key (channel id, bucket) — where bucket is a fixed time window. What each half does channel id matches the read pattern. Clients read messages within a chan
Equifax was breached in 2017 through a vulnerability with a patch available two months earlier. Beyond "patch faster", what architectural and governance failures does that imply?
The case, as publicly reported Apache Struts vulnerability CVE 2017 5638 was disclosed in March 2017 with a patch available. An internet facing dispute portal a
In July 2019 a single regex deployed globally took Cloudflare's network to 100% CPU within seconds. What does this say about how configuration should be released?
The case, as publicly reported On 2 July 2019, Cloudflare deployed a new managed WAF rule. It contained a regular expression that caused catastrophic backtracki
In the 2017 AWS S3 outage, the status page could not report the outage because it depended on S3. What does that tell you about designing status and control systems?
The case, as publicly reported On 28 February 2017, an authorised engineer running an established playbook to debug an S3 billing issue in us east 1 entered a c
In the October 2021 Meta outage, engineers reportedly struggled to physically access equipment because the access-control systems were also down. What class of dependency is that, and how do you find yours?
The case, as publicly reported On 4 October 2021, a command issued during routine backbone capacity assessment took down all connections between Meta's data cen
Instagram served 14 million users with three engineers on Django and Postgres. What does that tell you about how to choose an architecture for a new product?
What the interviewer is testing Whether you can identify the binding constraint. For most products it is not traffic. What Instagram actually did Their 2011 pos
Knight Capital lost roughly $460M in 45 minutes in 2012 after a deployment reached seven of eight servers. Which architectural failures made that possible, and which one would you fix first?
The case, as publicly reported Per the SEC's 2013 order, Knight Capital deployed new order routing code to eight production servers ahead of a NYSE programme la
Maersk rebuilt roughly 4,000 servers and 45,000 PCs in about ten days after NotPetya in 2017, and recovered its directory only because one data centre had been offline during the attack. What does this say about DR design?
The case, as publicly reported In June 2017 the NotPetya malware — destructive rather than financially motivated — propagated through Maersk's network, encrypti
Netflix built its own CDN; Dropbox moved storage off S3. Both are usually wrong. What conditions made them right, and how do you test for those conditions?
What the interviewer is testing Whether you can extract the conditions from a famous decision rather than the decision itself. These two cases are the most comm
Netflix personalises an entire home page in the time a TV takes to draw a screen. How, given that scoring every title for every member on request is impossible?
What the interviewer is testing Whether you reach for the offline/online split — the single most reusable idea in latency critical personalisation — rather than
Modernisation Business Case
Pricing tail risk so deferred maintenance becomes fundable.
Business Architecture
General material on the business side of architecture.
Business Capabilities
What a business does, stated stably and independent of implementation.
Business Cases
Expressing an architecture proposal in the currency that gets funded.
Business Continuity
What the business does while the system is unavailable.
Business KPIs
The numbers a design is ultimately judged against.
Business Metrics
Orders per minute alongside error rate, because healthy is not enough.
Business Processes
How work actually flows, including the handoffs nobody documented.
Business Understanding
Connecting a design to the outcome that pays for it.
API Gateways
The single entry point, and the business logic that must stay out of it.
Build vs Buy
Differentiation versus table stakes, priced over five years.
Capability Mapping
Overlaying systems onto capabilities to expose duplication and gaps.
Domain Boundaries
Where the language of the business changes, and services should too.
EA Domains
Business, application, data and technology architecture as viewpoints.
Judgement Under Uncertainty
Choosing the best worst case when information is missing.
Operating Models
How delivery, platform and governance functions fit together.
Organisational Constraints
Team structure, skills and budget cycles as architectural inputs.
Outbox
Making the event atomic with the business write it describes.
Outcome Measurement
Knowing whether the thing you built achieved what it promised.