Networking Media Abstraction, Device Discovery, and Routing for the Pervasive Middleware PalCom

PalCom is a pervasive middleware that can be used to assemble services provided by networked devices into configurations, called assemblies, for specific use cases by the user. In this dissertation, we present the development of a networking media abstraction framework for PalCom that abstracts different network interfaces in a PalCom device to upper layers of PalCom. The media abstraction framework is documented in paper I. Over the media abstraction layer, we define a device discovery mechanism that enables a PalCom device to discover other devices on its local networks, where it has network interfaces, as well as across interconnected networks. The device discovery mechanism is documented in paper II. On top of the device discovery layer, we implemented support for distance vector routing that enables routing data among discovered devices via the least cost routes. The routing layer is documented in paper III. In the last phase of our work, we refined our device discovery mechanism for PalCom to include a distributed synchronization algorithm that two PalCom nodes can utilize to re-sync their exchanged views of the network to overcome possible loss of device discovery and undiscovery notifications over unreliable channels. The synchronization algorithm is documented in paper IV

Synchronizing Device Discovery on Loss of Update Messages in the Pervasive Middleware Palcom

PalCom is a pervasive middleware that enables users to combine the services on devices into useful configurations. Interconnected PalCom devices can discover, and keep track of, the existence of each other by exchanging periodic heartbeats within local networks, and once-sent device appearance/disappearance notifications across interconnected networks. This approach has the advantage of eliminating the need to forward periodic heartbeats beyond the boundaries of the local networks of their originator devices. However, when a device appearance/disappearance notification is sent only once over an unreliable channel, there is a possibility of losing that notification. As a result, the device discovery information on PalCom devices will be out-of-sync. In this paper, we present the design, model-based evaluation, and the implementation status of a solution to this synchronization problem