SkyPackage: From Finding Items to Finding a Skyline of Packages on the Semantic Web

Enabling complex querying paradigms over the wealth of available Semantic Web data will significantly impact the relevance and adoption of Semantic Web technologies in a broad range of domains. While the current predominant paradigm is to retrieve a list of items, in many cases the actual intent is satisfied by reviewing the lists and assembling compatible items into lists or packages of resources such that each package collectively satisfies the need, such as assembling different collections of places to visit during a vacation. Users may place constraints on individual items, and the compatibility of items within a package is based on global constraints placed on packages, like total distance or time to travel between locations in a package. Finding such packages using the traditional item-querying model requires users to review lists of possible multiple queries and assemble and compare packages manually.

In this paper, we propose three algorithms for supporting such a package query model as a first class paradigm. Since package constraints may involve multiple criteria, several competing packages are possible. Therefore, we propose the idea of computing a skyline of package results as an extension to a popular query model for multi-criteria decision-making called skyline queries, which to date has only focused on computing item skylines. We formalize the semantics of the logical query operator,

Sky-Package

, and propose three algorithms for the physical operator implementation. A comparative evaluation of the algorithms over real world and synthetic-benchmark RDF datasets is provided.