ABSTRACT
Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 5.3 Problem Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 5.4 Context-Aware Approach for Device Search and Selection . . . . . . 77
5.4.1 High-Level Model Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 5.4.2 Capturing User Priorities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 5.4.3 Data Modelling and Representation . . . . . . . . . . . . . . . . . . . . . 80 5.4.4 Filtering Using Querying Reasoning . . . . . . . . . . . . . . . . . . . . 82 5.4.5 Ranking Using Quantitative Reasoning . . . . . . . . . . . . . . . . . 84 5.4.6 Context Framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
. . . . . . . . . . . 5.5.1 Comparative-Priority Based Heuristic Filtering
(CPHF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 5.5.2 Relational-Expression Based Filtering (REF) . . . . . . . . . . . 87 5.5.3 Distributed Sensor Searching . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
5.6 Implementation and Experimentation . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 5.7 Performance Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
5.7.1 Evaluating Alternative Storage Options . . . . . . . . . . . . . . . . 94 5.7.2 Evaluating Distributed Sensor Searching . . . . . . . . . . . . . . . 95
5.8 Open Challenges and Future Research Directions . . . . . . . . . . . . . . . 96 5.8.1 Context Discovery, Processing, and Storage . . . . . . . . . . . . 97 5.8.2 Utility Computing Models and Sensing as a Service . . . . 97 5.8.3 Automated Smart Device Configuration . . . . . . . . . . . . . . . . 98 5.8.4 Optimize Sensing Strategy Development . . . . . . . . . . . . . . . . 98
5.9 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Besides mobile sensing platforms and naming/addressing/profile services, searching functionality also plays a vital role in the domain of cyber-physical systems (CPS). Many different types of search capabilities are required to build a comprehensive CPS architecture. In CPS, users may want to search smart devices and services. In this chapter, we discuss concepts and techniques related to device search and selection. We briefly discuss different types of device searching approaches where each has its own objectives and applications. One such device searching technique is context-aware searching. In this chapter, we present context-aware sensor search, selection, and ranking model called CASSARAM in detail. This model addresses the challenge of efficiently selecting a subset of relevant sensors out of a large set of sensors with similar functionality and capabilities. CASSARAM takes into account user preferences and considers a broad range of sensor characteristics, such as reliability, accuracy, location, battery life, and many more. Later in the chapter, we discuss three different techniques that can be used to improve the efficiently of CASSARAM. We implemented the proof of concept software using Java. Testing and performance evaluation results are also discussed. We also highlight open research challenges and opportunities in order to support future research directions.
