A disconnected mobile ad hoc network (or D-MANET) is a wireless network, which because of the sparse distribution of mobile hosts appears at best as a partially or intermittently connected network. Designing and implementing distributed applications capable of running in such a challenged environment is not a trivial task. Middleware systems such as Java Message Service (JMS) have made application development easy and cost-effective in traditional wired networks. It can be expected that middleware systems designed specifically for D-MANETs bring similar benefits. In this paper, we introduce JOMS (Java Opportunistic Message Service), a JMS provider for D-MANETs with which pre-existing and new JMS-based applications can be deployed simply in D-MANETs.