Emerald Coast Vacation Rentals

The Problem: Emerald Coast By Owner manages hundreds of vacation rental properties across Florida's Gulf Coast. Property managers needed a way to verify that the rates quoted by their API matched what third-party listing sites (Airbnb, VRBO, Guesty) were actually charging guests. Rate discrepancies meant lost revenue or overcharges — and with hundreds of properties, manual spot-checking wasn't scalable.

The Approach: Build an internal rate comparison platform that pulls quotes from ECBYO's own API, breaks them down into line items (accommodation, fees, taxes, discounts), and compares them against host site rates. The catch: ECBYO's property and rate data lives in a remote MS SQL Server database, not MySQL. The PHP frontend needed to query SQL Server directly — and have a fallback ASP.NET Core proxy API for when firewall rules change.

What Was Hard: The dual-database architecture was the central challenge. The PHP application connects to a remote MS SQL Server (via ODBC Driver 18) for property data and rate calculations, while using a local MySQL database for audit logs and comparison history. The rate calculation engine implements a four-tier resolution strategy — Length of Stay rates take precedence, then seasonal rates (with weekend differentiation), then nightly flat rates, then an external API call as last resort. Each tier queries different SQL Server tables with different schemas. Getting the fee, tax, and discount calculations to match ECBYO's own API output exactly — including edge cases like per-night vs percentage fees, optional vs required charges, and early/late booking discounts — required extensive validation against production data.

The ASP.NET Core proxy API was built as a bridge layer: when direct SQL Server access isn't available from the PHP server, the proxy runs on localhost:5050 and forwards authenticated requests. This gives the system resilience against network policy changes without rewriting the PHP application.

The Result: A production internal tool with rate comparison auditing, third-party integration dashboards (Guesty, Rentals United, Breezeway), a database explorer for the SQL Server schema, and IP-whitelisted admin access. Active client contract since April 2026.