System Architecture
The DOI PSM is a mission-critical middleware solution designed to handle high-throughput transactional requests (primarily DOI/Push notifications). It serves as a robust buffer between client applications and sensitive downstream infrastructure (like OTA/HSM servers), ensuring reliability through asynchronous processing, rate limiting, and failure recovery.
Component Breakdown
Client Application
The upstream business system initiating the request (e.g., a CRM or Provisioning Portal).
HTTP/1.1, REST (JSON/XML)
PSM API Gateway
The secure entry point. Responsible for TLS termination, JWT validation, payload schema validation, and request logging.
Nginx/Kong, HTTPS
Redis Cache
A high-performance in-memory datastore used for distributed rate limiting (Token Bucket), idempotency checks (to prevent double-billing), and ephemeral session state.
Redis (Cluster Mode), TCP
PostgreSQL (DB)
The system of record. Stores the immutable history of every transaction, including state changes, timestamps, and audit logs for reconciliation.
PostgreSQL 14+, SQL
Message Queue
A durable message broker ensuring reliable delivery. It acts as a shock absorber, allowing the API to accept bursts of traffic while workers process at a steady pace.
RabbitMQ / ActiveMQ (AMQP)
PSM Worker
The core processing unit. A scalable fleet of services that consume messages, handle HSM cryptography logic, and manage persistent SMPP binds.
Java/Go/Node.js, Internal Logic
HSM (OTA Server)
The High Security Module responsible for generating the specific cryptographic payload (APDU) required to update the SIM card.
Proprietary HTTP/XML Interface
SMPP Gateway (SMSC)
The Short Message Service Center that delivers the binary payload to the mobile network via the SS7 signaling layer.
SMPP v3.4 (Transceiver Mode)
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