Frugal Mobile Objects

This paper presents a computing model for resource-limited mobile devices. The originality of the model lies in the integration of a strongly-typed event-based communication paradigm with abstractions for frugal control, assuming a small footprint runtime. With our model, an application consists of a set of distributed reactive objects, called FROBs, that communicate through typed events and dynamically adapt their behavior reacting to notifications typically based on resource availability. FROBs have a logical time-slicing execution pattern that helps monitor resource consuming tasks and determine resource profiles in terms of CPU, memory, and bandwidth. The behavior of a FROB is represented by a set of stateless first-class objects. Both state and behavioral objects are referenced through a level of indirection within the FROB. This facilitates the dynamic changes of the set of event types a FROB can accept, say based on the available resources, without requiring a significant footprint of the underlying FROB runtime. We demonstrate the usability of the FROB model through our Java-based prototype and a peer-to-peer audio streaming scenario where an audio provider dynamically adjusts its quality of service by adapting to demand. The performance results of our prototype convey the small footprint of our FROB runtime (86 kilobytes). We also augmented the KVM to enable resource profiling with however a negligible overhead (less than 0.5%) and a decrease in speed of the virtual machine of at most 7%.