Sustained Software for Cyberinfrastructure: Analyses of Successful Efforts with a Focus on NSF-funded Software.

ABSTRACTReliable software that provides needed functionality is clearly essential for an effective distributed cyberinfrastructure (CI) that supports comprehensive, balanced, and flexible distributed CI. Effective distributed cyberinfrastructure, in turn, supports science and engineering applications. The purpose of this study was to understand what factors lead to software projects being well sustained over the long run, focusing on software created with funding from the US National Science Foundation (NSF) and/or used by researchers funded by the NSF. We surveyed NSF-funded researchers and performed in-depth studies of software projects that have been sustained over many years. Successful projects generally used open-source software licenses and employed good software engineering practices and test practices. However, many projects that have not been well sustained over time also met these criteria. The features that stood out about successful projects included deeply committed leadership and some sort of user forum or conference at least annually. In some cases, software project leaders have employed multiple financial strategies over the course of a decades-old software project. Such well-sustained software is used in major distributed CI projects that support thousands of users, and this software is critical to the operation of major distributed CI facilities in the US. The findings of our study identify some characteristics of software that is relevant to the NSF-supported research community, and that has been sustained over many years.