Case Study 08

Dialer Architecture Revamp

Decomposed monolithic NestJS dialer into modular Go services with gateway-based routing and zero-downtime deployments.

Gateway

Architecture

3 Independent

Handlers

Zero-Downtime

Deployment

gRPC

Communication

The Problem

Monolithic NestJS dialer needed to be decomposed into modular Go services for better performance, independent scaling, and zero-downtime deployments.

The Solution

Designed gateway-based architecture with 2 replicas handling all Twilio webhooks
Manual, Inbound, and Predictive handlers run as separate stateless processes
Shared State Service (gRPC), Realtime Service (WebSocket), and Task Queue Service
Gateway routing table in Redis — stateless, any replica handles any request
Zero-downtime deployment: deploy new version → health check → update routing → drain old version
Monorepo structure with cmd/ and internal/ packages

Architecture

/call-system
├── cmd/
│   ├── gateway/main.go
│   ├── manual/main.go
│   ├── inbound/main.go
│   ├── predictive/main.go
│   └── taskqueue/main.go
├── internal/
│   ├── gateway/ (router, health, twiml, fallback)
│   ├── handler/
│   │   ├── base.go (shared logic)
│   │   ├── manual/
│   │   ├── inbound/
│   │   └── predictive/ (distributor, amd, compliance)
│   ├── state/ (Redis-backed call/agent state)
│   ├── realtime/ (WebSocket hub)
│   └── taskqueue/ (async processing)

Tech Stack

Golang gRPC Redis PostgreSQL Twilio Docker

Related Case Studies

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