How We Built an IoT Platform That Handles 30 Million Concurrent Connections — With a Team of 10

How We Built an IoT Platform That Handles 30 Million Concurrent Connections — With a Team of 10 DGIOT is an open-source industrial IoT platform. We run 928 gateways across 16 oil fields, process 652 million data points, and maintain 99.9999% uptime. Here's the architecture that makes it possible. The Problem In 2021, we got a call from Daqing Oil Field — China's largest oil producer. They had a problem: 928 industrial gateways from different vendors 114,809 sensor points speaking 15 different protocols Data collection every 10 minutes (they needed seconds) 15-30 minute end-to-end latency (they needed <3 seconds) False alarm rate above 20% The existing system was a patchwork of vendor-specific tools, each with its own database, UI, and authentication. Operators had to log into 8 different systems just to check if a pump was overheating. They asked: "Can you unify this?" What We Built DGIOT is an Erlang/OTP-based platform that acts as a universal translator for industrial protocols. Think of it as a Rosetta Stone for machines. Modbus ─┐ OPC UA ─┤ MQTT ──┼──→ Unified Pipeline ──→ TDengine ──→ Dashboard IEC104 ─┤ A11 ──┘ The key insight: industrial protocols are just state machines . Once you model each protocol as a gen_statem FSM in Erlang, you can handle hundreds of them concurrently with almost zero overhead. The Architecture: DLAS We designed a four-layer architecture that separates concerns cleanly: Layer 1: DATA — Ingestion Parse Server (23 classes) handles device metadata, user auth, tenant isolation TDengine stores 652M time-series data points with 10:1 compression EMQX handles MQTT message routing at 1M+ msg/sec Mnesia/ETS provides in-memory caching for hot data Layer 2: LOGIC — Ontology Engine This is our secret weapon. We built a 252-entity OWL ontology that models industrial equipment: Pump ⊑ Equipment ⊓ ∃ hasPart.Bearing ⊓ ∃ measures.Pressure Bearing ⊑ Component ⊓ ∃ hasFailureMode.Overheat Overheat → triggers ( Alert ) ∧ reduces ( RemainingLife , 0.8 ) The