Innovative Application Development for Ubiquitous and Wearable Computing

78 Chapter 5. General Concepts, Toolkits, and Frameworks Setting Layer The setting layer views collections of artifacts and has to establish connectivity among distributed artifacts. Table 2 summarizes the API for the setting layer. Table 5.4: Setting-layer Perception The discovery mechanism on this layer requires a distance measure that selects the range of sensor discovery: 0 - represents all local sensors on an artifact itself, 255 - all boards in connectivity range. All values in-between represent a distance measure based on the number of multiple communication hops required to reach a certain sensor. Based on this distance measure, each artifact can either query its neighbors on their primitives individually gained on the artifact layer, or it can remotely access sensors attached to other artifacts. By tuning the signal strength of the radio unit, the distance measure can be directly mapped to physical distances. The retrieval methods are built up the same way as on the artifact layer (see Section 4.2.1). The only di erence is that the universal identifier of the remote artifact to be addressed has to be included as a parameter. The main focus of the setting layer is to combine sensor information across artifacts. To this purpose two di erent integration paradigms have been implemented: