Object oriented frameworks impose additional burdens on programmers
that libraries did not, such as requiring the programmer to understand
the method callback sequence, respecting behavior constraints
within these methods, and devising solutions within a constrained
solution space. To overcome these burdens, we express
the repeated patterns of engagement with the framework as a design
fragment. We analyzed the 20 demo applets provided by Sun
and created a representative catalog of design fragments of conventional
best practice. By evaluating 36 applets pulled from the
internet we show that these design fragments are common, many
applets copied the structure of the Sun demos, and that creation of
a catalog of design fragments is practical. Design fragments give
programmers immediate benefit through tool-based conformance
assurance and long-term benefit through expression of design intent.