Protocols as well as application performance and behavior on Mobile Ad-hoc Networks (MANETs) are typically characterized using simulation or proof-of-concept deployment. Constraints presented by simulation environments however, fail to realistically model crucial parameters such as the load on the execution environment and interaction with other operating system processes, while proof-of-concept deployments may not accurately demonstrate scaling characteristics. This paper offers an alternative approach to testing and characterizing on-demand applications and services over MANETs by extending the Kasuari emulation framework. ns-2 was used to mimic the wireless layer of the MANET, while Xen was used to virtualize and generate a given number of wireless nodes. To test this framework, the researchers evaluated the impact of on-demand security mechanisms on a VoIP application streaming over a MANET with node movements.