In this PhD thesis a methodology for the objective error detection for the Ensemble composition architecture was proposed and developed. It can be used in the framework of the software life-cycle model, as a Parallel and Distributed Software Engineering process. It involves management of the software development process, and links design, implementation and testing in an integrated development process. Formal specifications of software components were used to validate the behaviour of composed applications. The logic followed is lightweight formal methods, which are applied during program execution as tools to assist error detection. A specifications composition technique, which is related to the composition of Ensemble and extends it to cover composition of formal specifications, was developed. An extension to the coloured Petri net model, called template CPN, which is capable to model the "pseudodynamic" modification of parametric interfaces of Ensemble components was proposed.Communication was modelled with Petri nets, covering all point to point communication operations for MPI and PVM. Finally the use of execution monitoring tools in synergy with specifications simulation tools was proposed. This synergy provides the ability to derive objective conclusions on the behaviour of the application and on the detection of possible errors.