A Survey on Visual Query Systems in the Web Era (extended version) <s> Web orientation <s> Abstract The Delaunay system supports a visual language that is specifically geared to the querying and visualization of databases. In this paper, we concentrate on the information visualization capabilities of the system. A distinctive feature of Delaunay is its full personalization capabilities: users can define their visualizations from scratch without limiting themselves to pre-defined visualization modes. Fine customization of the visualization is achieved by the availability of a visual alphabet of atomic graphical symbols and by the expressive power of the visual query language, which supports recursion. We describe the key components of the Delaunay system, namely its interface modules, which support advanced visualization techniques and principles, and its efficient constraint solver. The successful implementation of Delaunay demonstrates the feasibility of a powerful database system with which users can effectively specify a wide variety of visualizations supporting data and visualization exploration for different kinds of applications including graph visualization and business analysis. <s> BIB001 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Web orientation <s> The spreading of XML data in many contexts of modern computing infrastructures and systems causes a pressing need for adequate XML querying capabilities; to address this need, the W3C is proposing XQuery as the standard query language for XML, with a language paradigm and a syntactic flavor comparable to the SQL relational language. XQuery is designed for meeting the requirements of skilled database programmers; its inherent complexity makes the new language unsuited to unskilled users.In this article we present XQBE (XQuery By Example), a visual query language for expressing a large subset of XQuery in a visual form. In designing XQBE, we targeted both unskilled users and expert users wishing to speed up the construction of their queries; we have been inspired by QBE, a relational language initially proposed as an alternative to SQL, which is supported by Microsoft Access. QBE is extremely successful among users who are not computer professionals and do not understand the subtleties of query languages, as well as among professionals who can draft their queries very quickly.According to the hierarchical nature of XML, XQBE's main graphical elements are trees. One or more trees denote the documents assumed as query input, and one tree denotes the document produced by the query. Similar to QBE, trees are annotated so as to express selection predicates, joins, and the passing of information from the input trees to the output tree.This article formally defines the syntax and semantics of XQBE, provides a large set of examples, and presents a prototype implementation. <s> BIB002 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Web orientation <s> In this poster we discuss a graphical notation for representing queries for semistructured data. We try to strike a balance between expressiveness of the query language and simplicity and understandability of the graphical notation. We present the primitives of the notation by means of examples. <s> BIB003 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Web orientation <s> During the last decade, multidimensional databases have become common in the business and scientific worlds. Analysis places significant demands on the interfaces to these databases. It must be possible for analysts to easily and incrementally change both the data and their views of it as they cycle between hypothesis and experimentation. In this paper, we address these demands by presenting the Polaris formalism, a visual query language for precisely describing a wide range of table-based graphical presentations of data. This language compiles into both the queries and drawing commands necessary to generate the visualization, enabling us to design systems that closely integrate analysis and visualization. Using the Polaris formalism, we have built an interactive interface for exploring multidimensional databases that analysts can use to rapidly and incrementally build an expressive range of views of their data as they engage in a cycle of visual analysis. <s> BIB004 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Web orientation <s> Faceted metadata and navigation have become major topics in library science, information retrieval and Human-Computer Interaction (HCI). This work surveys a range of extant approaches in this design space, classifying systems along several relevant dimensions. We use that survey to analyze the organization of data and its querying within faceted browsing systems. We contribute formal entity-relationship (ER) and relational data models that explain that organization and relational query models that explain systems' browsing functionality. We use these types of models since they are widely used to conceptualize data and to model back-end data stores. Their structured nature also suggests ways in which both the models and faceted systems might be extended. <s> BIB005 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Web orientation <s> MashQL, a novel query formulation language for querying and mashing up structured data on the Web, doesn't require users to know the queried data's structure or the data itself to adhere to a schema. In this article, the authors address the fact that being a language, not merely an interface (and simultaneously schema-free), MashQL faces a particular set of challenges. In particular, the authors propose and evaluate a novel technique for optimizing queries over large data sets to allow instant user interaction. <s> BIB006 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Web orientation <s> Querying databases is a common daily task carried out by a great deal of end-users who do not have specific skills in SQL language. Today, most of the database interaction is achieved by means of query interfaces provided by the database environment. However, most of these interfaces suffer from expressive limitations, since they are mostly based on metaphors that drastically restrict the expressiveness of the SQL language that is generated and executed in the background. In this paper, we present a visual interaction language and tool focused on easily querying databases by end-users. We make no assumption on the level of the user's experience with query languages, as our visual metaphor is intended for querying databases by unskilled end-users and also leveraging the restriction on the expressiveness of the queries created by them. We also report on some late braking results obtained by an experiment carried out with real users. <s> BIB007
For the web orientation, we have selected two features which are not mutually orthogonal. The first feature is whether the prototype is working on the web or has been conceived to be used in local mode. For the first situation, the value is Available on the web and this means that the final user can query the database by means of a prototype which is working on the web. The two values are: -There is no web orientation -Available on the web The second feature indicates whether the user can query data formatted for the web and the values are: -Data not formatted for the web -Query XML data -Query RDF data The values are not orthogonal. So, a paper can have the two values. This is the case, for example, of paper BIB002 . In column 4 of Table 2 and of Table 3 , we summarise the orientation to the web of the VQSs. Regarding the data format, there are 9 papers [13,28,5,1,8,23,17,?,11] out of 34 which query XML data and only two papers which query RDF data BIB003 BIB006 . The rest of the papers do not query web data. The papers were available on the web BIB001 BIB002 BIB004 BIB005 BIB007 Delaunay BIB001 offers a prototype implemented in Java and is available on the www. XQBE BIB002 XQBE is fully implemented in a tool environment published on the Web and the implementation is based on a client-server architecture. The POLARIS system BIB004 has been adapted to the web, so it is possible to perform analysis within a browser. With the idea of the faceted interface, paper BIB005 points out that several prototypes are available on the web, for example, the prototype Flamenco from the University of Berkeley. In BIB007 , the VISQUE system is presented. This is based on a client-server architecture that includes a front-end which is a web-based authoring tool that allows users to visually interact with data elements and compose queries by example.