Software Licenses in Context: The Challenge of Heterogeneously-Licensed Systems

Article excerpt


The prevailing approach to free/open source software and licenses has been that each system is developed, distributed, and used under the terms of a single license. But it is increasingly common for information systems and other software to be composed with components from a variety of sources, and with a diversity of licenses. This may result in possible license conflicts and organizational liability for failure to fulfill license obligations. Research and practice to date have not kept up with this sea-change in software licensing arising from free/open source software development. System consumers and users consequently rely on ad hoc heuristics (or costly legal advice) to determine which license rights and obligations are in effect, often with less than optimal results; consulting services are offered to identify unknowing unauthorized use of licensed software in information systems; and researchers have shown how the choice of a (single) specific license for a product affects project success and system adoption. Legal scholars have examined how pairs of software licenses conflict but only in simple contexts. We present an approach for understanding and modeling software licenses, as well as for analyzing conflicts among groups of licenses in realistic system contexts, and for guiding the acquisition, integration, or development of systems with free/open source components in such an environment. This work is based on an empirical analysis of representative software licenses and of heterogeneously-licensed systems. Our approach provides guidance for achieving a "best-of-breed" component strategy while obtaining desired license rights in exchange for acceptable obligations.

Keywords: Open source software, software licenses, case study, semantic modeling, system architecture, design theory

1. Introduction

The hallmark of Free/Open Source Software (FOSS) is that the source code is available for remote access, open to study and modification, and available for redistribution to others with few constraints, except the rights and obligations that insure these freedoms. FOSS sometimes adds or removes similar freedoms or copyright privileges depending on which FOSS copyright and end-user license agreement is associated with a particular FOSS code base (Fontana et al., 2008; Rosen, 2005). Some licenses for "free software" such as the group of GNU General Public License (GPL) and Lesser General Public License (LGPL) versions (Free Software Foundation, 1991, 1999, 2007a, 2007b, 2007c) are well known and widely used, while others are obscure and sometimes specific to a particular software vendor. The Open Source Initiative (OSI, 2009), whose web portal gives information on many facets of FOSS, especially FOSS licenses, currently certifies more than 50 FOSS licenses, thus indicating a diverse ecology of freedoms, copying rights, and other license obligations and constraints.

Some FOSS licenses overlap or subsume one another's rights, while others present potential conflicts when comparing one license to another. Consequently, FOSS developers generally choose a single license to apply to their FOSS project, as part of their governance regime (de Laat, 2007). The choice of FOSS license to apply has been a defining characteristic of most FOSS projects, where the license chosen may connote not only an intellectual property sharing regime, but also a statement about beliefs, values, and norms expected to be shared by FOSS project developers, as well as affiliation within a larger social movement (Elliott and Scacchi, 2003, 2008, Roberts et al., 2006). However, a single license may not be sufficient to provide "copyleft" access to non-software specific data objects, representations, processing rules, or visual renderings. Similarly, with ever more FOSS components becoming available with different FOSS licenses - and some now even offered under multiple licenses1 - and given that different versions of a particular software component may have different licenses or license constraints, software and information system developers face a growing challenge: to determine how multiple software licenses interact, whether during system design (at "design time"), while compiling and linking source code to produce an executable program/binary (at "build time"), or when installing and running a newly acquired/downloaded version of software from a FOSS project or other provider that may need to interoperate with other software programs (at "run time"). …