Essays on distributed systems, on-call, postmortems, and survivable production.https://abualruz.com/enhttps://abualruz.com/writing/only-latency-budget/https://abualruz.com/writing/only-latency-budget/A story about picking one number, writing it on a whiteboard, and refusing to argue about anything else until production caught up with us.Wed, 01 Apr 2026 00:00:00 GMTlatencyperformanceon-callhttps://abualruz.com/writing/multi-tenant-recruitment/https://abualruz.com/writing/multi-tenant-recruitment/Talentera served enterprises and governments on one codebase. The data model survived years of tenancy demands because identity + access were first-class.Sun, 15 Mar 2026 00:00:00 GMTmulti-tenantidentityaccess-controlarchitecturehttps://abualruz.com/writing/local-llm-pipeline/https://abualruz.com/writing/local-llm-pipeline/Ollama on a GPU you own, llama.cpp for CPU work, vLLM for throughput — wired into the same engineering pipeline that runs your tests. Not a science project.Sun, 01 Mar 2026 00:00:00 GMTllmollamalocal-firstengineering-culturehttps://abualruz.com/writing/on-call-in-one-page/https://abualruz.com/writing/on-call-in-one-page/The list I hand new engineers on their first rotation: the habits that kept me sane, the runbooks that earned their keep, and the heroics I regret.Sun, 01 Feb 2026 00:00:00 GMTon-callsreincident-responsehttps://abualruz.com/writing/five-cli-agents/https://abualruz.com/writing/five-cli-agents/Most frame LLM-coding-agents as winner-takes-all. My reality: five in rotation, each good at a different local minimum, swapped atomically via a Go CLI I wrote.Thu, 01 Jan 2026 00:00:00 GMTaillmtoolsengineering-culturedeveloper-experiencehttps://abualruz.com/writing/second-system-effect/https://abualruz.com/writing/second-system-effect/Every rewrite I've watched die had the same warning signs. This is the checklist I now force every 'let's just rewrite it' conversation through.Mon, 01 Dec 2025 00:00:00 GMTarchitecturecomplexityrewriteshttps://abualruz.com/writing/wikipedia-boring-code/https://abualruz.com/writing/wikipedia-boring-code/Three years at Wikimedia: the systems serving half the planet are unglamorous PHP, careful caching, and operational culture — not architecture-astronaut stuff.Sat, 01 Nov 2025 00:00:00 GMTwikimediascalearchitectureoperationshttps://abualruz.com/writing/love-the-monolith/https://abualruz.com/writing/love-the-monolith/The modular monolith isn't a defeat — it's a design choice that keeps optionality open and the deploy story boring. Here's the case, with receipts.Wed, 01 Oct 2025 00:00:00 GMTarchitecturemonolithsmicroserviceshttps://abualruz.com/writing/ai-assisted-eng-new-collaborator/https://abualruz.com/writing/ai-assisted-eng-new-collaborator/After 3,400 commits running Claude Code, Codex, Gemini, PI, and OpenCode side-by-side: the pattern that works is clear, and most teams miss it.Mon, 01 Sep 2025 00:00:00 GMTaillmengineering-culturedeveloper-experiencehttps://abualruz.com/writing/design-doc-political/https://abualruz.com/writing/design-doc-political/Design docs aren't just technical specs. They're where organisational constraints meet engineering choices — and pretending otherwise ships you in circles.Fri, 01 Aug 2025 00:00:00 GMTdesign-docsengineering-managementwritinghttps://abualruz.com/writing/event-driven-that-shipped/https://abualruz.com/writing/event-driven-that-shipped/Most event-driven rewrites die with 80% of the bus built and zero hard problems solved. Here's what separated the one that shipped at Bytro from the graveyard.Tue, 01 Jul 2025 00:00:00 GMTevent-drivenarchitecturecqrsdistributed-systemshttps://abualruz.com/writing/interview-trivia-trench-coat/https://abualruz.com/writing/interview-trivia-trench-coat/A rant about the questions we keep asking because we were asked them — and a short list of what I actually learned replacing them with work samples.Sun, 01 Jun 2025 00:00:00 GMThiringinterviewingengineering-managementhttps://abualruz.com/writing/mumps-is-not-a-joke/https://abualruz.com/writing/mumps-is-not-a-joke/MUMPS runs Epic, VistA, and chunks of global healthcare. It turns 60. Every time I mention it in a meeting someone laughs — then finds out I'm serious.Thu, 01 May 2025 00:00:00 GMTmumpshealthcaredatabaseslegacyhttps://abualruz.com/writing/healthcare-paperwork-you-cant-see/https://abualruz.com/writing/healthcare-paperwork-you-cant-see/Years building EHRs taught me the visible UI is 15% of what makes a hospital system work. The other 85% is audit, regulation, and wire formats.Tue, 01 Apr 2025 00:00:00 GMThealthcareehrhl7fhirarchitecturehttps://abualruz.com/writing/fulcrum-agent-control-plane/https://abualruz.com/writing/fulcrum-agent-control-plane/Why I wrote a local-first agent control plane when dozens exist. TLDR: none handled the boring operational parts that make multi-agent work usable.Sat, 01 Mar 2025 00:00:00 GMTaiagentsfulcrumarchitecturehttps://abualruz.com/writing/mentor-mode-doc/https://abualruz.com/writing/mentor-mode-doc/A letter to every new software engineer about what nobody told me in my first decade. Specific habits that compound, with receipts from 15 years of shipping.Sat, 01 Feb 2025 00:00:00 GMTmentoringengineering-cultureonboardinghttps://abualruz.com/writing/auxmoney-fintech-lending/https://abualruz.com/writing/auxmoney-fintech-lending/What shipping AI-assisted lending workflows inside a regulated fintech backend actually looks like — Kafka, compliance, and the honest end of the story.Wed, 15 Jan 2025 00:00:00 GMTfintechevent-drivenkafkaai-integrationawskuberneteshttps://abualruz.com/writing/playing-captain/https://abualruz.com/writing/playing-captain/What it actually means to lead by staying in the code — and why 'engineering managers should stop coding' is advice for a different team shape than mine.Sun, 01 Dec 2024 00:00:00 GMTleadershipmanagementplaying-captainhands-onhttps://abualruz.com/writing/founding-afaq/https://abualruz.com/writing/founding-afaq/I founded a healthcare software company in Amman, managed 12 engineers, and shipped a cardiac hospital EHR in KSA. Here's what that actually looked like.Fri, 01 Nov 2024 00:00:00 GMThealthcareehrstartupleadershiphttps://abualruz.com/writing/hl7-khcc-integration/https://abualruz.com/writing/hl7-khcc-integration/I integrated King Hussein Cancer Centre with Jordan's national EHR via HL7 v2. Here's what the wire format looks like and why it's harder than it sounds.Tue, 01 Oct 2024 00:00:00 GMThealthcarehl7integrationinteroperabilityhttps://abualruz.com/writing/hakeem-national-ehr/https://abualruz.com/writing/hakeem-national-ehr/I spent three years building HAKEEM, Jordan's national EHR built on VistA. Here's what rolling out to four hospitals actually looked like from inside.Sun, 01 Sep 2024 00:00:00 GMThealthcarehakeemvistahl7https://abualruz.com/writing/vista-gtm-deep-dive/https://abualruz.com/writing/vista-gtm-deep-dive/What it actually felt like to write production MUMPS routines inside VistA — Pharmacy, Billing, HL7 — on GT.M in Linux. Not a joke. I was there.Thu, 01 Aug 2024 00:00:00 GMTmumpsvistagt.mhealthcarehttps://abualruz.com/writing/elevatus-multi-tenant/https://abualruz.com/writing/elevatus-multi-tenant/Building Elevatus: an AI-powered hiring platform where a government ministry and a retail chain shared the same codebase and nothing could break.Mon, 01 Jul 2024 00:00:00 GMTsaasmulti-tenantrecruitmentaihttps://abualruz.com/writing/tcl-tk-in-production/https://abualruz.com/writing/tcl-tk-in-production/How I shipped microservices and BPMN workflows on top of a TCL/TK core running on AOL servers, and why that was the right call.Sat, 01 Jun 2024 00:00:00 GMTtcllegacymulti-tenantsaashttps://abualruz.com/writing/gwt-spring-boot-era/https://abualruz.com/writing/gwt-spring-boot-era/I was doing type-safe full-stack Java when TypeScript was a 1.0 RC. GWT is gone now. Spring Boot is everywhere. Here's what that era actually felt like.Wed, 01 May 2024 00:00:00 GMTgwtspring-bootjavanostalgiahttps://abualruz.com/writing/blulogix-telecom-salesforce/https://abualruz.com/writing/blulogix-telecom-salesforce/What I learned building a cloud billing platform for telecom operators and integrating it with Salesforce when the data models fundamentally disagreed.Mon, 01 Apr 2024 00:00:00 GMTtelecombillingsalesforcegwthttps://abualruz.com/writing/network-admin-to-architect/https://abualruz.com/writing/network-admin-to-architect/What an unusual path through retail, LAN cables, and a gaming hall in Amman taught me that a straight line from CS degree to big tech never could.Fri, 01 Mar 2024 00:00:00 GMTcareerretailnetwork-adminearly-careerhttps://abualruz.com/writing/university-oss-club/https://abualruz.com/writing/university-oss-club/I co-founded a university OSS club in 2009 when open source was still an unusual pitch in the MENA region, and J2ME was a viable mobile platform.Thu, 01 Feb 2024 00:00:00 GMTopen-sourceteachingcareercommunityhttps://abualruz.com/writing/java-6-to-17/https://abualruz.com/writing/java-6-to-17/A working engineer's retrospective on 15 years of Java versions — not the spec, but what actually changed how I write code day to day.Mon, 01 Jan 2024 00:00:00 GMTjavakotlinjvmretrospectivehttps://abualruz.com/writing/meinrezept-pharmacy-backend/https://abualruz.com/writing/meinrezept-pharmacy-backend/What the e-prescription backend actually looked like in 2020: legacy pharmacy integrations, RabbitMQ, and engineering under pandemic pressure.Wed, 01 Jul 2020 00:00:00 GMThealthcaremicroservicesrabbitmqpandemicphpnodejshttps://abualruz.com/writing/payever-ecommerce-integrations/https://abualruz.com/writing/payever-ecommerce-integrations/What marketplace integration archaeology looks like up close: three different inventory models, two months, and one unified domain schema to rule them all.Fri, 01 May 2020 00:00:00 GMTnestjse-commerceintegrationrabbitmqtypescriptmongodb