Reusability in the software development realm is a momentous cornerstone in deciding the success of an organization. The quantum leap in reusability was provided by object-orientation, which fundamentally altered the manner of thinking of software architects. The notion of the object and the installation of reusability as one of the central tenets is a critical requisite. Components that represented bigger and better software aggregates easily utilized by businesses to gain instant execution for their business services have made great strides. This gave way to the ultimate notion of a service which took software aggregates in components to fine and sharpened streams of software execution called services. This has been another inflection point in the overall curve of reusability, and most importantly, in agility and turnaround time for software production. The notion of services mandated the birth of a secure and trusted public interface to a service, which is called the Application Programming Interface (API). APIs represent a directory of services that a given enterprise offers.
Denotational trace: a category-theoretic solution to the practical problems of software execution tracing
