  Software firms participate in an ecosystem as a part of their innovation
strategy to extend value creation beyond the firms boundary. Participation in
an open and independent environment also implies the competition among firms
with similar business models and targeted markets. Hence, firms need to
consider potential opportunities and challenges upfront. This study explores
how software firms interact with others in OSS ecosystems from a coopetition
perspective. We performed a quantitative and qualitative analysis of three OSS
projects. Finding shows that software firms emphasize the co-creation of common
value and partly react to the potential competitiveness on OSS ecosystems. Six
themes about coopetition were identified, including spanning gatekeepers,
securing communication, open-core sourcing and filtering shared code. Our work
contributes to software engineering research with a rich description of
coopetition in OSS ecosystems. Moreover, we also come up with several
implications for software firms in pursing a harmony participation in OSS
ecosystems.
