Reverse Engineering
When is it the most
cost effective?
Raymond Utz
The Problem
• When is Reverse Engineering the correct
choice over Forward Engineering?
Terminology
• Reverse Engineering - the process of
recovering the design conditions of a
legacy system that is currently being used
and that is not fully documented.
• Forward Engineering - is the process of
moving from high-level abstractions and
models to the physical implementation of a
system.
Benefits and Drawbacks of
Reverse Engineering
• There is already a
working system in
place
• If tools are available
then process can be
automated to an
extent
• The legacy system
could be very hard to
follow
• The lead software
engineers for the
legacy system are
usually not around
What and How to measure
• Looked at the Algorithmic Model:
– Effort = A x SizeB x M
– “A” is a constant factor for all local projects of
the same type
– “Size” is the number of lines of code or function
points
– “B” is usually assigned the values between 1
and 1.5
– “M” is a multiplier that consists of the sum of
process, product, and development attributes
Effort = A x SizeB x M
• The main difference between Reverse and
Forward Engineering in this model would
be the “Size”
• “M” would also vary because of the many
factors it is based on
Ethics
• Therac 25 system
– They Reverse Engineered code for different
hardware due to the cheaper cost
– A lot of the problems could have been stopped
by just Forward Engineering a new system
Conclusion
• To improve a system’s maintainability no
matter the size Reverse Engineering would
be the best choice
• To try and migrate a small system to new
hardware it would be beneficial to Reverse
Engineer the design as a means to
Reengineer the system.
– For a larger system Forward Engineering
would be beneficial