Abstract
As we all know too well, building up a collaborative community around a software infrastructure is not easy. Besides recruiting enthusiasts to work as part of it, mostly for free, to succeed you also need to overcome a number of technical, sociological, and, to our surprise, some political hurdles. The ALMA Common Software (ACS) was developed at ESO and partner institutions over the course of more than 10 years. While it was mainly intended for the ALMA Observatory, it was early on thought as a generic distributed control framework. ACS has been periodically released to the public through an LGPL license, which encouraged around a dozen non-ALMA institutions to make use of ACS for both industrial and educational applications. In recent years, the Cherenkov Telescope Array and the LLAMA Observatory have also decided to adopt the framework for their own control systems. The aim of the “ACS Community” is to support independent initiatives in making use of the ACS framework and to further contribute to its development. The Community provides access to a growing network of volunteers eager to develop ACS in areas that are not necessarily in ALMA's interests, and/or were not within the original system scope. Current examples are: support for additional OS platforms, extension of supported hardware interfaces, a public code repository and a build farm. The ACS Community makes use of existing collaborations with Chilean and Brazilian universities, reaching out to promising engineers in the making. At the same time, projects actively using ACS have committed valuable resources to assist the Community's work. Well established training programs like the ACS Workshops are also being continued through the Community's work. This paper aims to give a detailed account of the ongoing (second) journey towards establishing a world-wide open source collaboration around ACS. The ACS Community is growing into a horizontal partnership across a decentralized and diversified group of actors, and we are excited about its technical and human potential.
