The Strudel system applies concepts from database management systems to the process of building Web sites. Strudel's key idea is separating the management of the site's data, the creation and management of the site's structure, and the visual presentation of the site's pages. First, the site builder creates a uniform model of all data available at the site. Second, the builder uses this model to declaratively define the Web site's structure by applying a "site-definition query" to the underlying data. The result of evaluating this query is a "site graph", which represents both the site's content and structure. Third, the builder specifies the visual presentation of pages in Strudel's HTML-template language. The data model underlying Strudel is a semi-structured model of labeled directed graphs. We describe Strudel's key characteristics, report on our experiences using Strudel, and present the technical problems that arose from our experience. We describe our experience constructing sev...

", "Author". In addition it constructs a special node Authors() and connects it to all pages corresponding to "Author"s. The output graph is called SiteGraph. One way to write this in StruQL is: input DataGraph where Root(x); x ! ! y; y ! l ! z; l in f"Paper", "TechReport", "Title", "Abstract", "Author"g create Authors(); Page(y); Page(z) link Page(y) ! l ! Page(z) where x ! ! y1; y1 ! "Author" ! z1 link Authors() ! "Author" ! Page(z1) output SiteGraph 2 In order to integrate information from several source, we allow multiple input graphs. When multiple input graphs are present, every occurrence of a collection needs to be preceded by a graph name. For clarity of presentation however, we focus on queries with only one input graph. Intermixing the where; create; link clauses makes the query easier to read. This is nothing more than syntactic convenience, since the meaning is the same as that of the query in which all clauses are joined together: input DataGraph where Root(x...

syntax level. At this level, we apply source-to-source transformations to reduce the number of edges that must be traversed in the input graph. We do this by finding common prefixes in multiple regular path expressions. For example, consider: where Root(p); p ("A":"B"):"A" q; p "A":"C":"D" r We can rewrite the first regular expression into an equivalent expression: where Root(p); p "A":("B":"A") q; p "A":"C":"D" r Next, we introduce two node variables, x and y: where Root(p); p "A" x; x ("B":"A") q; p "A" y; y "C":"D" r Finally, if q and r are "independent", meaning that none of the clauses in link creates and edge between them, then we can collapse the x and y node variables into a single variable z, and get: where Root(p); p "A" z; z ("B":"A") q; z "C":"D" r The resulting query is equivalent to the original, but it traverses each edge "A" accessible from the root once. Automaton level. At this level, each regular expression is translated into a generalized NDFA. There is one ...

Introduction The growth of the World-Wide Web has created a new kind of data management problem: building and maintaining Web sites. Building a Web site involves several tasks, such as choosing what information will be available at the site, organizing that information in individual pages or in graphs of linked pages, and specifying the visual presentation of pages in HTML. Creating and managing large sites is tedious, because a user often must perform these tasks simultaneously when creating HTML pages. The task of building and managing Web sites presents a unique opportunity for applying concepts from database management systems, such as the separation between the logical view of information and its storage and maintenance and the ability to restructure information via queries. Furthermore, recent research results on information integration [Ull97] and managing semi-structured data [ACM97, Abi97] can play a key role in managing Web sites. The goal of strudel

The Strudel system applies concepts from database management systems to the process of building Web sites. Strudel's key idea is separating the management of the site's data, the creation and management of the site's structure, and the visual presentation of the site's pages. First, the site builder creates a uniform model of all data available at the site. Second, the builder uses this model to declaratively define the Web site's structure by applying a "sitedefinition query " to the underlying data. Third, the builder specifies the visual presentation of pages in Strudel's HTML-template language. The data model underlying Strudel is a semistructured model of labeled directed graphs. In this paper we describe Strudel's architecture and the key characteristics. We report on our experience using Strudel, present the technical problems that arose from our experience and discuss the impact of potential users' requirements on Strudel's design.