QFTP — Section: Section 8.2

For performance/dependability analysis the models are usually stochastics. How to specify distributions ? The "statisticalQualifier" attribute associated to a <<QoS dimension>> attribute allows to declare that the type of value of the attribute is a distribution but not the "type of distribution". On the other hand, a syntax is not given for the specification of the type of distribution as well as, in general, for complex timing values. To illustrate a possible solution let us consider a system UML model in which we want to specify the service time for two resources COM and MEM as random variables distributed according to the uniform PdF and to the negative exponential PdF, respectively. The annotation has to be as simple as possible but at the same time detailed enough to be useful for the construction of a stochastic model.