One of the promises of the service-oriented architecture(SOA) is to build complex added-value services in order to enhance and extend existing ones. service-based applications(SBAs) are asked not only to perform required functionalities,but also to deliver expected level of Quality of Service (QoS). Dealing with QoS management of such distributed applications, which are executed in dynamic environments,raises the need to consider context characteristics.This paper proposes a discrete-events simulation approach which assures the evaluation of SBAs performance under different context status. The main contributions of this paper are: (i) the discrete-events modeling approach for SBAs, (ii) the context-based model for SBAs considered in the discrete-events simulation model, and (iii) the evaluation of a set of QoS metrics by simulation.