Real-Time Support Chat API

I need a seasoned backend developer to architect and code the APIs that will drive an instant-response customer-support chat and text-messaging service. The data layer is fixed on MySQL, so you will design the schema, write migrations, and ensure every query scales cleanly under load... (Budget: $250 - $750 USD, Jobs: API Development, Backend Development, Database Design, Java, JavaScript, MySQL, PHP, RESTful)