With the proliferation of laptops, smart phones, sensors and other small devices, our physical environment is increasingly networked. Applications in a variety of problem domains (e.g., intelligent construction, traffic monitoring, smart homes, etc.) need to efficiently and seamlessly execute on top of such emerging infrastructure. Such infrastructure tends to be unreliable, and the network configuration changes constantly (network hosts depart and reemerge frequently). Consequently, software has to be able to react to these changes continuously and change its behaviors accordingly. In this dissertation, I introduce PAQ (Persistent Adaptive Query), a middleware designed to ease the programming burden associated with writing such applications. PAQ employs a novel style of query-driven application development that allows programmers to build pervasive applications by employing persistent queries--queries that continuously monitor the environment. The dissertation discusses the design and implementation of a new middleware model that allows programmers to write high level specifications abstracting away several tedious implementation details. PAQ employs both novel protocols that automatically tag the quality of information obtained from the network and statistical techniques to post-process and smooth the data. The goal of this research is to ease the software engineering challenges encountered during the construction and deployment of several applications in emerging pervasive computing environments thorough the use of a query-driven application development paradigm. / text

As the number of the published web services increase, discovery of the web services with the desired functionality and quality is becoming a challenging process. Selecting the appropriate web services among the ones that oer the same functionality is also a challenging task. The web service repositories like UDDI (Universal Description Discovery and Integration) support only the syntactic searchs. Quality of service parameters for the published web services can not be queried over these repositories. We have proposed a query language that aims to overcome these problems. It enables its users to query the web services both syntactically and semantically. We also allow the users to specify the quality of service criteria which the desired web services should satisfy. We have developed a graphical query interface to assist the users in query sentence formulation process. The proposed work is developed as a submodule of the Domain Specific Web Service Discovery with Semantics (DSWSD-S) System. Aforementioned query language and the query interface are explained in detail in this thesis.