CrossJam: A language for hypermedia authoring

Current hypermedia systems take little advantage of the structure in documents, even those that have a formal syntax. For example, while HTML is nominally a structured document format, HTML markup mostly serves as presentation directives to a Web browser.;The thesis of this dissertation is that hypermedia systems can provide interesting new services by being extended with scripting language features to transform structured documents. These scripting language features can be implemented without a prohibitive performance penalty.;The key principle is an analogy to the way compilers operate on programs, which are highly structured documents. Compilers use the context provided document structure to guide a transformation process defined by a language's formal semantics. In hypermedia systems, documents have much less structure and little to no formal semantics, making it non-obvious how to take advantage of such context. CrossJam is a language design that collects a small set of useful programming language features that formalize and generalize the process of scripting document transformations. The dissertation identifies opportunities in hypermedia systems, where CrossJam's capabilities can be used to take advantage of document structure.;To validate the viability of this technique, we have developed Argent, an extension module for the Apache HTTP server, written Grendel, a prototypical Web browser, and implemented Asante, a Macromedia Director Xtra. In each system, CrossJam's features are exposed to end users.;These applications demonstrate functionality, based upon CrossJam's language features, that current hypermedia systems generally can not deliver. Many such systems could be reprogrammed or extended to achieve such capabilities but in a much less elegant fashion. At the same time, we benchmarked a sample of Web applications that use CrossJam. Acceptable execution speed was achieved, especially in the context of the World Wide Web, where the network, not processing speed, is the major bottleneck. Altogether, the dissertation documents a viable set of scripting language features that can be used to extend the capabilities of hypermedia systems and capabilities of hypermedia systems and scripting languages.