API Versioning as a Translation Layer
API versioning as an architecture: requests enter through a version header, pass through a chain of reversible version changes, and reach controllers that only ever see the latest model.
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Architecture
830 posts about Architecture. Every summary links to the original.
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Architecture explainers
BIAN as a Contract Layer: Modernizing Core Banking One Domain at a Time
BIAN gives banks a shared vocabulary and service-domain contracts that sit between business concepts and the systems implementing them. See how domains, contracts, and governed access stack into one architecture.
Argo CD: The Reconciliation Loop Between Git and Your Cluster
Argo CD is a GitOps controller that treats Git as the desired state and continuously reconciles it against what actually runs in each cluster. It maps the parts of that loop and why pull-based agents change its scale.
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The Story Behind Shopify’s Isospin Tooling
Shopify’s Isospin is the systemd-based core of Spin, its in-house cloud development platform, designed to run multiple applications inside a single Linux VM. The earlier implementation relied on shell scripts, but growing application counts made it difficult to split applications into components, express dependencies, schedule jobs, and isolate processes. Isospin uses systemd unit graphs, targets, template units, and generators to create service configurations dynamically, including per-application copies of dependencies such as MySQL and Elasticsearch. Additional tooling assigns semi-stable ports by hashing service names and uses systemd readiness notifications, including a notify-port wrapper that checks HTTP availability; the resulting system reuses systemd’s dependency and health mechanisms, with more complex cross-application relationships under investigation.
Graph Networks - 10X investigation with Graph Visualisations
Fraud detection traditionally required investigators to manually combine large datasets from disparate anti-fraud systems using statistical methods, which proved slow and inefficient. Grab built an interactive Graph Visualisation platform to transform raw records into connected visual maps without requiring manual queries or switching tools. The platform manages over three billion nodes and edges, allowing investigators to selectively expand data points and replay chronological events using temporal filters. Visual relationship mapping helps teams verify account appeals, uncover device-sharing rings, and spot anti-money laundering behavior through transaction density patterns.
The Serverless Server
The post explains what “serverless” means by reconstructing the machinery beneath a Lambda-like platform. It starts with bare-metal x86 servers, a Type 1 hypervisor, and services for placement, VM management, request forwarding, and function execution; dedicated customer workers, shared warm pools, rate limits, and container-style isolation address multitenancy, cold starts, and bursty demand. The runtime design uses object storage for function code, chroot, privilege dropping, namespaces, seccomp, cgroups, and freezing to constrain idle instances and workloads. Its limits on initialization, invocation duration, and idle lifecycles support migration away from unhealthy instances but disadvantage applications with expensive startup, dynamic local caches, or uncertain response times.
Navigating Recurring Payments in India: A Backend Perspective
India’s October 2021 Reserve Bank of India (RBI) directive required recurring payments to use payer-authorized e-mandates, Additional Factor of Authentication (AFA), and pre-debit notifications at least 24 hours before charges. Shopify’s billing platform therefore had to model e-mandates, support recurring and one-time payments across cards and Unified Payments Interface (UPI), and integrate a local payment provider. The payment service reused its source object for the e-mandate token, recorded the temporary authorization as a charge for auditability, and refunded it asynchronously. To avoid two consecutive card authentication flows, the team used recurring-payment tokenization for both payment paths, accepting an atypical notification experience as a short-term trade-off; UPI required asynchronous webhook-driven handling and a hard mandate limit. After the beta launch, billing-payment success rates in India increased from pre-project levels, and the team said it would soon make UPI generally available to Indian merchants.
How We Built Shopify Party
Shopify Party is a browser-based internal tool designed to make virtual hangouts more social and reduce video fatigue after Shopify moved to remote work. Its 3D spaces favor non-prescriptive play, letting participants explore and manipulate objects, join or leave at any point, and use a small control set rather than follow prescribed rules or win conditions. The initial version was built in three months with Unity 2020 and the Universal Render Pipeline, exported to WebGL, while Normcore synchronizes game state, provides VoIP and networked physics, and uses room time to keep autonomous objects aligned across clients. Performance work included third-party assets, GPU instancing for repeated models, simpler materials, and adjustable render resolution. The launch exceeded expectations, with hundreds of games played each week, and the tool is positioned as an option alongside video conferencing rather than a replacement.
Director of Machine Learning Insights [Part 3: Finance Edition]
Machine learning leaders in financial institutions face significant operational hurdles when integrating automated models into production environments. Practitioners must navigate complex legacy architectures, strict regulatory oversight, and privacy mandates tied to personally identifiable financial records. Integrating models often fails when organizations lack clear communication buffers, deploy models using improper prediction windows, or treat systems as opaque black boxes without verifying underlying mechanics. Despite these challenges, financial applications increasingly rely on machine learning for anti-money laundering compliance, automated fraud screening, and loan underwriting. Success in this regulated sector demands comprehensive evaluation across representative input spaces, robust ongoing model monitoring, and explainable decision outputs.
How facial recognition technology keeps you safe
Grab utilizes facial recognition technology across its platform for driver authentication, passenger verification, and digital electronic Know Your Customer (e-KYC) processes. The core pipeline consists of image preprocessing through face detection and alignment, anti-spoofing checks, feature extraction into high-dimensional vector embeddings, and downstream verification or search. To counter spoof attacks like screen replays, synthetic moiré patterns are generated and cropped face patches are used during training and inference to focus on local structures rather than global semantic noise. Face verification challenges involving shallow ID datasets and masked faces are resolved using semi-Siamese training architectures and masked data augmentations.
The Journey to Cloud Development: How Shopify Went All-in on Spin
Shopify’s development environment, the Ruby-based dev tool and xhyve-backed railgun VM, no longer handled the growing number of repositories, services, integrations, and resource demands around its monoliths. Developers needed more services, faced sluggish code-build-test loops, and encountered costly state changes when tophatting collaborators’ work. The Environments team concluded that development environments needed cloud-like elasticity, then tested an automatically configured local Kubernetes cluster and easy creation of Google Compute Engine VMs; the source also describes Isospin and Spin as the resulting direction. Local Kubernetes did not gain broad organic traction, while the current Isospin implementation is described as the team’s best iteration for developers working on majestic monoliths. The team plans to evolve it into an application-development library built on dev, add dependency inference, and address the tension between persistent environments and Kubernetes pod relocation.
Graph concepts and applications
Real-world systems generate dynamic, non-random connections that traditional statistical approaches fail to characterize or forecast. Graph models represent these structures through vertices and edges, abstracting complex networks into mathematically tractable relationships. Common data representation formats include the Resource Description Framework (RDF), which models subject-predicate-object triples with IRIs, literals, and blank nodes, and Labeled Property Graphs (LPGs), which store arbitrary key-value properties directly on nodes and edges. Graph databases, derived from the LPG model, treat relationships with equal weight to entities, delivering responsive traversals for highly interconnected systems. While they offer agility and explicit relationship modeling, graph databases lack a standardized query language and remain poorly suited for standard transaction-focused workloads compared to relational databases.
To Thread or Not to Thread: An In-Depth Look at Ruby’s Execution Models
Threaded servers such as Puma and thread-based Sidekiq are popular Ruby deployment choices because threads can increase throughput without a proportional increase in memory. The post compares process and thread models using a memory model that separates static application memory from per-request processing memory, then refines it with Copy on Write (CoW), where forked processes share pages until writes force copies. It explains why RSS can double-count shared pages, recommends PSS and Linux’s /proc/$PID/smaps_rollup for more meaningful measurements, and gives a production example in which about two-thirds of static memory is shared. The conclusion is metric-dependent: preload applications to improve CoW, prefer fewer larger containers when appropriate, consider Unicorn for reliable request timeouts, and start web workloads at two threads unless substantial I/O wait justifies more; job processors may benefit from higher counts.
Automated Experiment Analysis - Making experimental analysis scalable
Manual ad-hoc analysis of online controlled experiments at Grab introduced operational inefficiencies, inconsistent quality control, and scalability barriers across teams. To resolve these issues, Grab extended its GrabX experimentation platform with an Automated Experiment Analysis system that standardises metrics and automates statistical evaluations. The architecture stores experiment configurations and metric definitions from Cosmos DB into Azure Data Lake as bronze datasets, uses Spark on Databricks via Azure Data Factory to process subjects into silver datasets, and applies an internal Python Decision Engine to generate final gold results. These gold datasets are stored in star-schema fact and dimension tables and presented directly in the GrabX interface using embedded Power BI visualisations. The automation eliminates repetitive data pipeline construction for analysts, ensures reproducible findings aligned with initial hypotheses, and accelerates product launch decisions.
Our Favorite Moments From RailsConf 2022
RailsConf 2022 returned to an in-person format at Portland’s Oregon Convention Center after a two-year gap, with three days of keynotes, tutorials, and talks on technical and workplace topics. The 16th edition announced three new Rails Core team members, including Shopify’s Jean Boussier, and two new committers, while recurring themes included company investment in Rails, security, Active Records, “build vs buy,” diversity, and burnout. Shopify’s 15 Rails speakers contributed sessions and keynotes, and the recap gathers highlights on open-source staffing, long-term maintenance, developer wellbeing, Rails upgrades, supply-chain attacks, and modularization for “Big Rails.” Specific examples included regexp DOS risks, typosquatting and combosquatting, Rails upgrade automation, Ruby Archaeology, and the history of women in computer science. Because concurrent sessions and hallway conversations limited attendance, a virtual home edition and recordings were scheduled to make more talks available afterward.
Double Entry Transition Tables: How We Track State Changes At Shopify
Shopify needed a reliable way to count merchants using Shopify Balance over time, where usage requires both an active Shopify Balance account and an active Shopify account. The data team built accounts_transition_facts with double entry transition tables, a format that represents each state change as a -1 row for the previous state and a +1 row for the new state. Individual attribute tables use account_id, transition_at, and an index that breaks timestamp ties; the pipeline merges attributes, carries forward missing values, and generates net_change rows. Because net_change is additive, queries can sum it while filtering statuses, group results by date, or feed daily aggregates, while additional attributes can be added without rewriting existing SQL or PySpark. The initial build required substantial effort but produced a reporting structure intended to scale with Shopify Balance’s growing complexity.
Search architecture revamp
Before 2021, Grab’s Deliveries search architecture used an inverted index for textual matching, leaving it unable to account for user intention, context, or non-textual recall methods. Queries such as “Roti Prata” could prioritize merchant names over dishes, while the same query could imply different objectives by time or location; merging Ads and organic results at the Deliveries API layer also discarded recall-stage data. The revamped flow adds boosting, multi-recall, and ranking, enabling intent recognition, query expansion, embedding-based and graph-based recall, and joint ranking across business verticals. A platform-defined framework assembles service-team plugins through configuration, separating core flow from application logic and allowing components such as Ads and Mart recall to be reused across Food, Mart, and universal search flows. The resulting platform provides intent recognition, semantic search, mixed Ads-and-organic ranking, and simpler onboarding, while making new search modules and use cases easier to add.
Maestro: The Orchestration Language Powering Shopify Flow
Shopify developed Maestro, a domain-specific orchestration language, to decouple Shopify Flow’s merchant-facing visual editor from its execution engine, whose requirements differ in declarative usability versus scalable, fault-tolerant execution. The team introduced a horizontally scalable Maestro engine, translated existing Flow workflows into Maestro, migrated them incrementally, and later connected a new visual language directly to Maestro; all workflows had moved to the new editor and engine by early 2022. Maestro coordinates calls to host-language functions rather than implementing service or database operations, while durable checkpoints capture completed work and let the interpreter recover after crashes with at-least-once semantics for primitive calls. During activation, static usage analysis identifies needed returned attributes for possible query optimization, and compilation removes runtime-irrelevant definitions before deployment; checkpoints also support execution monitoring, while planned work includes richer language features, orchestration merging, and workflow preview and testing.
Our Experience Porting the YJIT Ruby Compiler to Rust
Shopify’s YJIT team moved the CRuby JIT compiler from C99 to Rust after finding that C’s limited complexity-management tools made the growing project difficult to maintain. The port had to preserve a non-trivial interface with CRuby, including parsing bytecode and manipulating Ruby’s primitive types, while compiling the Rust project into a static library linked through CRuby’s makefile. The team translated functions and structs largely one by one, retaining the original architecture while using Rust features such as pattern matching, macros, Cargo features, and borrow checking. Completed in three months, the port was judged more maintainable and pleasant to work with, although the team identified challenges around C interoperability, unsafe code, tooling, ecosystem maturity, and limited use of idiomatic Rust.
React Native Skia—For Us, For You, and For Fun
React Native Skia brings Skia’s cross-platform 2D drawing primitives to React Native, with the stated goals of improving its limited graphical capabilities and aligning designers and developers around capabilities comparable to Figma. The integration uses React Native’s JavaScript Interface (JSI), enabling direct JavaScript-to-native communication through C++ rather than asynchronous messages, and exposes an API described as virtually 100% compatible with Flutter’s. On top of the imperative API, a declarative layer uses the React Reconciler to diff internal representation states and send changes to the Skia engine, supporting composable drawings and declarative optimizations. The library includes image filters, shaders, SVG, path operations, vertices, text layouts, mesh gradients, shadows, backdrop blur, and animations, with a direct connector to Reanimated 2; the authors expect it to address a major React Native pain point and describe the work as just beginning.
Graph Networks - Striking fraud syndicates in the dark
Grab's Integrity team faced escalating threats from organized fraud syndicates operating device farms and GPS spoofing tools that mimic normal user behavior. To overcome the limitations of traditional rule-based systems, Grab built a Graph-based Prediction Platform that links entities across shared attributes to expose hidden network structures. The architecture includes a scalable graph database platform holding over one billion nodes, powering real-time graph visualization for analysts alongside a configurable network feature extraction system. In addition, the team deployed Graph Neural Networks to capture structural correlations across transaction networks. These systems collectively help detect coordinated promo abuse, payment fraud, and complex money laundering schemes.
Building a Business System Integration and Automation Platform at Shopify
Shopify needed a maintainable way to connect increasingly modular business systems whose interfaces ranged from SOAP and FTP to REST and GraphQL. The company evaluated Mulesoft but found that its proprietary XML and Java virtual machine stack isolated the team from Shopify’s development ecosystem and complicated access to internal services and infrastructure. It instead built a Ruby on Rails integration platform around minimal validation, transparent data transformations, flexible client support, security, reusable components, documentation, and request-level testing with WebMock. The implementation favors direct manipulation of JSON hashes because that keeps mappings visible, while acknowledging risks such as typos and complex mock management. After a year, the platform had 18 integrations, had migrated all Mulesoft applications, and enabled other teams to build integrations, with ongoing work on testing and onboarding.
Möbius: Shopify’s Unified Edge
Shopify had more than six traffic paths for its core, services, PII-restricted systems, and mTLS-authenticated APIs, making platform-wide features harder to deploy and traffic behavior harder to observe. Möbius and Shopify Front End (SFE) were designed together: Möbius terminates TCP and TLS near clients and forwards requests to SFE, while SFE routes them from regional clusters to application clusters. SFE uses nginx deployments with custom Lua and a centralized API fed by Kubernetes controllers, enabling routing and active/active or active/passive load balancing without DNS TTL delays. Möbius automates edge domain configuration, DNS ownership validation, and certificate acquisition through vendor APIs, so application owners generally only need to change DNS. The unified design standardizes edge protection and observability, supports future edge capabilities, and leaves exceptions for services whose dependencies could create crash loops.
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