  This article describes requirements and challenges of crossplatform
multi-touch software engineering, and presents the open source framework
Multi-Touch for Java (MT4j) as a solution. MT4j is designed for rapid
development of graphically rich applications on a variety of contemporary
hardware, from common PCs and notebooks to large-scale ambient displays, as
well as different operating systems. The framework has a special focus on
making multi-touch software development easier and more efficient. Architecture
and abstractions used by MT4j are described, and implementations of several
common use cases are presented.
