Open source software (OSS) is computer software that has its underlying source code made available under a licence. This can allow developers and users to adapt and improve it (Raymond, 2001). Computer software can be broadly split into two development models: • Proprietary, or closed software, owned by a company or individual. Copies of the binary are made public; the source code is not usually made public. • Open-source software (OSS), where the source code is released with the binary. Users and developers can be licenced to use and modify the code, and to distribute any improvements they make. Both OSS and proprietary approaches allow companies to make a profit. Companies developing proprietary software make money by developing software and then selling licences to use the software. For example, Microsoft receives a payment for every copy of Windows sold with a personal computer. OSS companies make their money by providing services, such as advising clients on the GPL licence. The licencee can either charge a fee for this service or work free of charge. In practice, software companies often develop both types of software. OSS is developed by an ongoing, iterative process where people share the ideas expressed in the source code. The aim is that a large community of developers and users can contribute to the development of the code, check it for errors and bugs, and make the improved version available to others. Project management software is used to allow developers to keep track of the various versions. There are two main types of open-source licences (although there are many variants and subtypes developed by other companies): • Berkeley Software Distribution (BSD) Licence: This permits a licencee to “close” a version (by withholding the most recent modifications to the source code) and sell it as a proprietary product; • GNU General Public Licence (GNU, GPL, or GPL): Under this licence, licencees may not “close” versions. The licencee may modify, copy, and redistribute any derivative version, under the same GPL licence. The licencee can either charge a fee for this service or work free of charge. Free software first evolved during the 1970s but in the 1990s forked into two movements, namely free software and open source (Berry, 2004). Richard Stallman, an American software developer who believes that sharing source code and ideas is fundamental to freedom of speech, developed a free version of the widely used Unix operating system. The resulting GNU program was released under a specially created General Public Licence (GNU, GPL). This was designed to ensure that the source code would remain openly available to all. It was not intended to prevent commercial usage or distribution (Stallman, 2002). This approach was christened free software. In this context, free meant that anyone could modify the software. However, the term “free” was often misunderstood to mean no cost. Hence, during the 1990s, Eric Raymond and others proposed that open-source software was coined as a less contentious and more business-friendly term. This has become widely accepted within the software and business communities; however there are still arguments about the most appropriate term to use (Moody, 2002). The OSMs are usually organised into a network of individuals who work collaboratively on the Internet, developing major software projects that sometimes rival commercial software but are always committed to the production of quality alternatives to those produced by commercial companies (Raymond, 2001; Williams, 2002). Groups and individuals develop software to meet their own and others’ needs in a highly decentralised way, likened to a Bazaar (Raymond, 2001). These groups often make substantive value claims to support their projects and foster an ethic of community, collaboration, deliberation, and intellectual freedom. In addition, it is argued by Lessig (1999) that the FLOSS community can offer an inspiration in their commitment to transparency in their products and their ability to open up governmental regulation and control through free/libre and open source code.
Measuring the Effectiveness of Adaptive Random Forest for Handling Concept Drift in Big Data Streams
