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Software Architect & Full-Stack Developer | Wallety (2009)

Executive Summary

Engineered an online payment gateway built to handle high-concurrency payment settlements in Egypt under unstable telecommunications infrastructure. The platform integrated directly with banking gateways and the Amadeus Global Distribution System (GDS), scaling to process 33% of all domestic air travel ticketing volume across Egypt.

1. Context & Business Problem

  • ->Client / Domain: Wallety (Fintech / Payment Gateway)
  • ->Timeline: 2009
  • ->Project Role: Software Architect & Full-Stack Developer

//The Problem

During 2009, regional banking APIs in Egypt suffered from high timeout rates and lack of standardized payment interfaces. Airlines and merchants required a fault-tolerant intermediary payment engine that could guarantee transactional consistency without losing booking state during network interruptions.

2. Technical Stack & Systems Infrastructure

  • ->Application Framework: Symfony (PHP), enforcing domain separation and isolated payment state machines.
  • ->Data Layer: MySQL with Master-Slave replication separating write-heavy transaction processing from read-heavy reporting.
  • ->Infrastructure: AWS compute nodes behind Elastic Load Balancers terminating SSL.
  • ->Background Processing: Long-running CLI daemons executing asynchronous queue loops every second.

3. Core Architectural Decisions

  • ->Deterministic Transactional State Machine: Implemented explicit state tracking (Pending, Authorized, Settled, Failed, Reconciled) with automated polling to reconcile dropped bank callbacks.
  • ->Master-Slave Database Topology: Dedicated the master database node strictly to ACID-compliant writes while routing reporting and transaction audit queries to read replicas, eliminating disk I/O contention.
  • ->Atomic GDS Booking Alignment: Enforced atomic database transactions that coupled flight seat reservation locks in Amadeus GDS with payment gateway authorization confirmations to prevent double bookings.
  • ->Asynchronous Queue Orchestration: Decoupled synchronous HTTP request handling from slow upstream bank gateway settlements using background CLI queue workers.

4. Operational & Business Impact

  • ->Scale & Throughput: Scaled payment processing throughput to support 33% of domestic air travel ticketing in Egypt.
  • ->System Resilience: Maintained consistent transaction reconciliation despite frequent external bank network drops.
  • ->Queue Latency: Sustained 1-second queue processing intervals during ticket sale spikes, insulating checkout flows from gateway latency.