Sudarshan Murthy

Mash-o-matic

Web applications called mash-ups combine information of varying granularity from different, possibly disparate, sources. We describe Mash-o-matic, a utility that can extract, clean, and combine disparate information fragments, and automatically generate data for mash-ups and the mash-ups themselves. As an illustration, we generate a mash-up that displays a map of a university campus, and outline the potential benefits of using Mash-o-matic. Mash-o-matic exploits superimposed information (SI), which is new information and structure created in reference to fragments of existing information. Mashomatic is implemented using middleware called the Superimposed Pluggable Architecture for Contexts and Excerpts (SPARCE), and a query processor for SI and referenced information, both parts of our infrastructure to support SI management. We present a high-level description of the mash-up production process and discuss in detail how Mash-o-matic accelerates that process.

Querying bi-level information

In our research on superimposed information management, we have developed applications where information elements in the superimposed layer serve to annotate, comment, restructure, and combine selections from one or more existing documents in the base layer. Base documents tend to be unstructured or semi-structured (HTML pages, Excel spreadsheets, and so on) with marks delimiting selections. Selections in the base layer can be programmatically accessed via marks to retrieve content and context. The applications we have built to date allow creation of new marks and new superimposed elements (that use marks), but they have been browse-oriented and tend to expose the line between superimposed and base layers. Here, we present a new access capability, called bi-level queries, that allows an application or user to query over both layers as a whole. Bi-level queries provide an alternative style of data integration where only relevant portions of a base document are mediated (not the whole document) and the superimposed layer can add information not present in the base layer. We discuss our framework for superimposed information management, an initial implementation of a bi-level query system with an XML Query interface, and suggest mechanisms to improve scalability and performance.

Superimposed Information Architecture for Digital Libraries

A variety of software tools commonly used in research and industry allow a user to select (usually contiguous) segments of content to be annotated, referenced, or otherwise distinguished from a containing document. However, digital libraries (DLs) often curate only full documents, not these selected sub-documents. Thus, sub-documents in a DL may not have the full complement of metadata, and they may not be visible using DL browse and search facilities. We are interested in explicit representation of sub-documents in a DL environment. In this paper, we show how sub-documents may be represented and curated. We focus on the explicit representation of what we call a mark- an encapsulated address of a sub-document along with associated context. Our contributions are: a software architecture for representing marks as first-class objects together with regular documents in a DL; and an implementation of our architecture using existing software packages with modest enhancements. This approach provides new capabilities for the DL with minimal modification to tools and interfaces familiar to the DL user.

Superimposed applications using SPARCE

People often impose new interpretations onto existing information. In the process, they work with information in two layers: a base layer, where the original information resides, and a superimposed layer, where only the new interpretations reside. Abstractions defined in the Superimposed Pluggable Architecture for Contexts and Excerpts (SPARCE) ease communication between the two layers. SPARCE provides three key abstractions for superimposed information management: mark, context, and excerpt. We demonstrate two applications, RIDPad and Schematics Browser, for use in the appeal process of the US Forest Service (USFS).

Explicitly representing superimposed information in a conceptual model

Superimposed information (SI) refers to new information such as annotations and summaries overlaid on fragments of existing base information (BI) such as web pages and PDF documents. Each BI fragment is referenced using an encapsulated address called a mark. Based on the widespread applicability of SI and wide range of superimposed applications (SAs) that can be built, we consider here how to represent marks explicitly in a conceptual model for an SA. The goal of this work is to facilitate the development of SAs by making it easy to model SI (including the marks) and to exploit the middleware and query capability that we have developed for managing marks and interacting with the base applications. The contribution of this paper is a general-purpose framework to make marks explicit in a conceptual (ER) model. We present conventions to associate marks with entities, attributes, and relationships; and to represent that an attributes value is the same as the excerpt obtained from a mark. We also provide procedures to automatically convert ER schemas expressed using our conventions to relational schemas, and show how a resulting relational schema supports SQL queries over the combination of SI, the associated marks and the excerpts associated with the marks.

Cloaking data to ease view creation, query expression, and query execution

XML schemas often allow many aspects of an object to be described in the same document, but queries over such documents might be concerned with just one aspect. For example, an XML representation of a spreadsheet can include both spreadsheet data and styling, but a query might address only the data portions. In these situations, traditional approaches first define a data-only view and then query that view. However, these approaches can make it hard to define views and to express queries; and in some cases (even with view unfolding), they can even make query-execution inefficient in terms of time and space. We propose cloaking document parts and selectively revealing the cloaked parts as an alternative. Cloaking exposes many simultaneous conceptual views of a document without constructing new data, allows queries to be expressed in existing languages, and it can be easily supported in existing query processors. In this paper, we present a formal model for cloaking, its application in a cloaking query processor, and the results of an experimental evaluation in the context of superimposedinformation (SI, information with references to existing information) and bi-level information (SI along with the referenced information). Our experiments suggest that cloaking can make it easier to define views and to express queries, and that for certain query classes, a cloaking query processor saves both time and memory when compared to a traditional query processor.