Flight Hub is highly available, highly recoverable and runs simultaneously in more than one place -- unlike the mainframe, which offered redundancy within a single data center but had no backup site. "The program objective was to enable true disaster recovery," Hassell says.
The Flight Hub ESB consists of three main components. Applications can access data on demand, receive information on a regular schedule and send and receive data through topic-based publish/subscribe messaging. In the latter case, applications can subscribe to or publish information to update current flight times or let staff know when a crew can no longer legally continue to fly because they must rest, for instance. "The Horizon architecture uses standard distributed [computing] patterns using message queues and service calls between components," Hassell says.
"Flight Hub is a hybrid. It provides ESB capabilities and provides services to other applications," and passes data to and from the mainframe, Hassell says. In this way, it can pass data to and from any application and keep all data in synch.
After completing Flight Hub, American created a new relational data store to hold flight operations data, and began bringing in new applications. Hassell's team has been rewriting or replacing existing mainframe FOS applications for Flight Hub, one at a time, as well as writing and acquiring new ones. "Horizon was not keen on writing applications. Our strategy from the beginning was buy versus build," she says. "We continue to be thoughtful about which applications should be built." So far American has 22 applications deployed, with 20 in development, and has connected a total of 55 applications to Flight Hub, including the AA.com Web site.
Around 20% of the completed applications were written from scratch, Hassell says; the rest were purchased and modified as needed.
The latest applications include:
A revamp of the Aircraft Communications Addressing and Reporting System (ACARS), which allows text-based messaging between the cockpit and the personnel -- usually the dispatcher responsible for that flight, or operations. American runs ACARS on AIRCOM Server, an off-the-shelf product it acquired from Geneva-based SITA.
A tool that shows aircraft locations on the taxiway.
A mobile crew check-in app.
An aircraft tracking application with routes of flight for dispatchers.
"We can seamlessly pass information to all of those applications and we don't have to modify them any more from an integration perspective," Hassell says.