We are witnessing a tremendous expansion in computational power, leading to monumental technological advances with various practical applications. The need for parallelism originated from the limitations of single-processing performance. Increasing the transistor density on integrated circuits was the way to go, thus creating faster and more complex monolithic processors. However, these circuits approached their limits of hardware expansion, so the single-processor model has become unreliable and insufficient overall. This is how multicore architectures were born and, with them, the notion of parallel computing. Our research background in the Drop Computing paradigm and Interest in studying parallel programming paradigms encouraged us to propose a new approach towards parallel processing in mobile, ad-hoc, opportunistic networks. This paper adapts one fundamental message-passing standard for parallel architectures within the Drop Computing context. We define a new library DroMPI. Besides the challenges of parallel programming, the solution has to address the challenges imposed by hardware constraints, limited resources, and the decentralized model specific to Drop Computing.