Chapter 3. Transactions

One of the issues we run into when differentiating among different technologies used in software fortress architectures is transactions. So before I look too closely at software fortresses , I will spend some time on transaction basics.

According to Microsoft's Encarta computer dictionary, a transaction is "a discrete activity within a computer system, such as an entry of a customer order." This is an overly simplistic definition, making a transaction sound like little more than a read request to a disk drive. Transactions are much more important and a lot more complex than Microsoft's Encarta, or even most database folks, would have you believe.

Transactions come in three standard varieties: (1) tightly coupled single-resource, (2) tightly coupled multiple-resource , and (3) loosely coupled multiple-resource. These three varieties differ in how they coordinate updates across different transactionally aware resources.