Web Commerce Security Design and Development

Scalability

In general, scalability is the property exhibited by a system or service wherein an increase of resources results in improved performance proportional to the additional amount of resources.

Scaling can be implemented in both centralized and distributed Web commerce systems. In centralized systems, vertical scaling, or scaling up, is accomplished by increasing the size or capability of existing or fewer resources. In distributed systems, as used in Web commerce, horizontal scaling is the addition of more of the individual resource elements, such as servers. In addition to providing improved performance, horizontal scaling is used to implement redundancy and reliability of loosely coupled systems. Thus, distributed systems are more resilient and can tolerate failures of some resource units. This ability to reliably effect horizontal scaling is an important factor in the success of Web commerce computing.

Generally, vertical scaling is easier to implement, but is more expensive. Also, there is a possibility of a single point of failure. Horizontal scaling is usually less costly, more resilient, but relatively more difficult to implement than vertical scaling.

Horizontal scaling is particularly applicable to Web 2.0 in that, as applications expand, there is a corresponding decrease in performance. Because most applications are data intensive in Web commerce, significant improvements in performance can be achieved by horizontally scaling the database. This scaling involves ...