Traditionally, software, in the form of computer-executable instructions embodied on a computer-readable medium, has been distributed by providing users with a single version of such software through a compact disk (CD) or other computer-readable medium that simultaneously comprises all of the software's computer-executable instructions. Such distribution mechanisms required specific update cycles, where new versions of software were released by announcing their availability and requiring existing users to obtain new CDs or other computer-readable media.
An increasingly popular method of software distribution, however, eschews computer-readable media that simultaneously comprise all of the software's computer-executable instructions in favor of computer-readable media, such as computer networking hardware and connections that deliver the software's computer-executable instructions to a user on an as-needed basis. Such real-time delivery of computer software enables developers to continuously update their software, and allows users to continuously obtain the most up-to-date version. In particular, the software, and distribution environment can be such that the user must obtain the computer-executable instructions from a centralized location each time the user executes the software. In addition, the nature of the software's delivery encourages the use of distributed computing techniques, whereby one or more components of the software would be executing on the user's computing device, while one or more other components of the software would be executing on a centralized server computing device remote from the user's computing device.
Often, software that is delivered using real-time distribution mechanisms seeks to provide platform-independent functionality. For example, one environment in which real-time distribution of software is prevalent is the World-Wide Web (WWW), where software comprises both computer-executable instructions executing on a server computing device and, operating in concert, scripts that are downloaded by and executed by a web browser. Because web browsers exist for a variety of hardware and software platforms, including computing devices based on differing microprocessor architectures and computing devices executing differing operating systems, software that is incompatible with one or more of these platforms risks losing popularity by immediately excluding some percentage of users. Consequently, web-based software delivered in a real-time manner generally seeks to provide functionality for users of multiple computing platforms. Unfortunately, because of the heterogeneity of client computing devices, the developers of software delivered in a real-time manner can be handicapped when attempting to test their software in a manner approximating an expected range of usage once deployed.
As software delivered in a real-time manner increases in complexity, it is not just the heterogeneity of client computing devices that can cause difficulties for the developers of such software. Other factors, such as the workload generated by the software, or its dependence on third-party services and networks, can likewise render the creation and maintenance of such software more difficult.