event driven web shop

aka Event Thingy Store

setup in docker

make setup

setup on host

Terminal 1

cd shared
make run

Terminal 2

cd backend
make import
make run

Terminal 3

cd frontend
make run

Required tools for development

• golang
• air https://github.com/cosmtrek/air
• elm
• elm-live
• protoc
• protoc-gen-elm https://www.npmjs.com/package/protoc-gen-elm
• docker

Features

• automatic rebuild backend
• automatic rebuild frontend
• wait free reads
• removed rw lock
• load all data before starting to serve requests

Rules

• keep read short
• all state exists as persisted event / kafka is the only source of truth
• avoid (syncronous) network calls
• minimize overhead in data flow, data access, code structure

Roadmap

sync frontend

• websocket
• localstorage
• tab open

backend

• extract simba
  • [DONE] lock: exclusive, sharedread, waitfree
  • [SKIP] serialize: json, protobuf
  • [DONE] configure: massage wrapper
  • [DONE] processing: batch & finalize vs single-step
  • batch only during start vs dynamic selection
  • [DONE] sync to other contexts before processing commands
• extend simba to create bridges
  • share events between contexts
• CORS
  • configurable api domain in frontend
  • configurable spa domain in backend
  • http handler wrapper for CORS setup
• production docker image
• limit cpu and memory use locally
• remove .uuid
• [DONE] use context specific data structs
• [DONE] generalize context
• tests for handlers * cqrs & context
• [DONE] context with swapable model & read-write lock
• liveness probe / readiness probe
  • check kafka
  • remember last connection and let that be the test
  • the processor needs to signal, that it is stuck (msg unknown)
• /metrics endpoint for prometheus
  • add model size, writes, writetime, readtime, reads, handler calls to metrics
  • hook into sarama metrics to expose
• add timeouts & retries & exponential backoff & shedding & circuitbreaking & avoid thundering heard
• ensure ordered cart is exactly the cart shown in the browser
• better startup
  • snapshots
  • add a confirmation email
  • when triggering an sideeffect, then ensure to do this only once
  • after dirty shutdown wait for ip ttl
• use https://godoc.org/github.com/golang-collections/go-datastructures/slice/skip#SkipList.ByPosition
• debug
  • tracing via jaeger
  • debugger local
  • debug prod system
  • cpu & memory profiler
  • browser events in kafka
  • copy prod events to local

frontend

• production image
• remove .uuid
• use int32 everywhere https://package.elm-lang.org/packages/eriktim/elm-protocol-buffers/latest/#known-limitations
• use less & cleanup css classes from html elm
• [DONE] use protobuf / remove json
• [DONE] use modules
• use urls & links
• only process results matching the current model
• configure backend url
• tests
• add timeouts & retries & exponential backoff & shedding & circuitbreaking & avoid thundering heard

general

• create an uneasy environment https://github.com/Netflix/SimianArmy/tree/master/src/main/resources/scripts
• e2e tests
• add pim
• add fulfilment
• add cms
• add search

Maybe later (stick to basics and prove of concept first)

• tilt

Failed ideas

• use arc cache to skip marshal from struct to json