Transactional integrity is part and parcel of the mainframe era, but it is undergoing some shifts in the age of the Web. Development leaders are finding this as throngs of front-end Web users 'hit' the back-end mainframe. It is left up to the software architect to balance dueling system objectives.

Going forward, both the mainframe and the Web front-end have distinct roles to play, according to a noted industry analyst. James Governor, principal analyst and founder of RedMonk, spoke about mainframe transaction processing at IBM Impact 2012 in Las Vegas in a session on IBM's Z-series and transactional integrity issues.

Software designers should work to gain a good understanding of those roles in order to succeed with increasingly stressed Web application architectures, Governor stated.

“Scale really is going gangbusters,” he exclaimed. The growing “Internet of things” and a big rush of Smartphone-style devices will stress systems, he indicated. 

Workloads are going up significantly, a large mainframe user agreed. But the mainframe supporting a key lodging system can handle the load, said Misha Kravchenko, vice president, Information Services, Marriott International.

Kravchenko estimates that Marriott books 800,000 room-nights every day using a central operations system that “has no down time.” This workload has gone up in recent years, as Marriott strived to consolidate distributed workloads on an IBM Z-class machine. Clearly, the Web has been a disruptive force in a business that was once largely dependent on call centers, travel agents and the plain old telephone.

He anticipates further dramatic increases upcoming when mobile applications truly take off. Marriott has recently released mobile tools that help travelers find nearby hotels, book rooms and check on reservations. Many of these mobile users are part of the Marriott Rewards program.

Central to understanding the issue of transactions, said analyst Governor, is an understanding of the ''CAP'' theorem of computer scientist Eric Brewer. ''CAP'' here stands for ''Consistency-Availability-Partition Tolerance.''

Brewer concluded that a system designer could typically only mandate two of these three traits in a design. Cloud poster child Amazon.com is famous for putting ''eventual consistency'' ahead of immediate transactional consistency in its flagship e-commerce system.

The mainframe crew takes a much different view of these transactional traits. In Governor’s words: ''Mainframe people want all three.''

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