Composing pervasive services can be a challenging task, especially in networks where connectivity disruptions are prevalent and unpredictable, such as in networks formed spontaneously by connected things. In this paper, we propose a REST service composing system for such networks. This system has been built upon an opportunistic computing middleware to support connectivity disruptions. It implements orchestration-based and choreography-based composition techniques, and uses inter-contact time average as a metric to carry out the composition process.