Software engineering: What do experiments need

This paper will review the use of software engineering in High Energy Physics experiments and will suggest ways in which that use will change significantly in the future. In Principle, experiments do not need software engineering. We can verify this by looking at a long series of experiments that have succeeded without it. Some experiments that have tried to apply formal engineering methods have given them up before the software was complete. Future experiments, however, face many new challenges in the larger data samples, larger and more distributed collaborations and longer time scales. In addition, new tools are available to aid in the development of complex software systems. It is appropriate, therefore, to examine whether there is now a better match between software engineering and the needs of experiments.