—Employing hierarchically nested component structures can give end users increasing
control over their applications [Won et al. 2006].
—Assembling components is a complex task that requires a visual component integration
formalism in order to validate the integration carried out at data type level and
a level closer to the domain expert, where data semantics are compared.
—For end users to be able to develop composite applications, a components model has
to be defined with visual techniques that users use to interconnect such components.