Christine Tomlinson

The Carnot Heterogeneous Database Project: Implemented Applications

The Carnot project was an ambitious research project inheterogeneous databases. It integrated a variety of techniques toaddress a wide range of problems in achieving interoperation inheterogeneous environments. Here we describe some of the majorimplemented applications of this project. These applications concern(a) accessing a legacy scientific database, (b) automating a workflowinvolving legacy systems, (c) cleaning data, and (d) retrievingsemantically appropriate information from structured databases inresponse to text queries. These applications support scientificdecision support, business process management, data integrityenhancement, and analytical decision support, respectively. Theydemonstrate Carnot‘s capabilities for (a) heterogeneous queryprocessing, (b) relaxed transaction and workflow management, (c)knowledge discovery, and (d) heterogeneous resource modelintegration.

Using Carnot for enterprise information integration

The Carnot Project, which addresses the problem of logically unifying physically distributed, enterprise-wide, heterogeneous information is discussed. Specifically, Carnot will provide a user with the means to navigate information efficiently and transparently, to update that information consistently, and to write applications easily for large, heterogeneous, distributed information systems. The Carnot architecture and the Carnot tools for building applications are described.<<ETX>>

Carnot and InfoSleuth: database technology and the World Wide Web

The Carnot research project [CARN, WOEL93] at MCC was initiated in 1990 with the goal of addressing the problem of logically unifying physically-distributed, enterprisewide, heterogeneous information. A prototype has been implemented that provides services for enterprise modeling and model integration to create au enterprise-wide view, semantic expansion of queries on the view to queries on individual resources, and interresource consistency management. Carnot also includes technology for 3D visualization of large information spaecs, knowledge discovery in databases, and software application design recovery. The Camot prototype software has been used by the sponsors of the Carnot project to develop a number of applications. These applications have included worldtow management, heterogeneous database access, knowledge discovery in large databases, and integrated access to both text databases and structured databases from a single initial query.

The extensible services switch in Carnot

The Carnot project for developing a flexible framework for integrating heterogeneous information resources and applications, both within and among organizations, is reviewed. The effective use of such systems requires a way to flexibly and efficiently orchestrate related tasks on far-flung computing systems. A central component of the Carnot project, the extensible services switch (ESS), which provides interpretive access to applications and to communications and information resources at distributed sites, is discussed. The ESS is described as essentially a programmable glue that enhances interoperability by binding software components to one another.<<ETX>>

InfoSleuth: networked exploitation of information using semantic agents

InfoSleuth is a research project at MCC that is developing and deploying new technologies for finding information available both in corporate networks and in external networks, such as networks based on the emerging National Information infrastructure (NII). The InfoSleuth research is based on the Carnot technology that has been developed at MCC over the last four years. Carnot has been successfully used to integrate heterogeneous corporate information resources. The InfoSleuth project will investigate the use of Carnot technology in a more dynamically changing environment, such as the Internet, where new information sources are constantly being added and for which there is no formal control of the registration of new information sources. In this type of environment, traditional techniques for expressing and optimizing database queries are inadequate because of the rapidly changing schema information and the fuzzy nature of the queries.

Task scheduling using intertask dependencies in Carnot

The Carnot Project at MCC is addressing the problem of logically unifying physically-distributed, enterprise-wide, heterogeneous information. Carnot will provide a user with the means to navigate information efficiently and transparently, to update that information consistently, and to write applications easily for large, heterogeneous, distributed information systems. A prototype has been implemented which provides services for (a) enterprise modeling and model integration to create an enterprise-wide view, (b) semantic expansion of queries on the view to queries on individual resources, and (c) inter-resource consistency management. This paper describes the Carnot approach to transaction processing in environments where heterogeneous, distributed, and autonomous systems are required to coordinate the update of the local information under their control. In this approach, subtransactions are represented as a set of tasks and a set of intertask dependencies that capture the semantics of a particular relaxed transaction model. A scheduler has been implemented which schedules the execution of these tasks in the Carnot environment so that all intertask dependencies are satisfied.

Relaxed transaction processing

Extended transaction models have drawn much interest recently in academia and industry [2]. Such models seek to address the limitations of traditional ACID transactions for supporting multisystem applications that operate in heterogeneous environments. Such applications are increasingly proving to be of strategic importance to a number of businesses and governmental agencies. Different transaction models, however, tend to be closed in that they cannot be easily combined with other such models, thus limiting their applicability to situations which exactly match one of them. We do not propose yet another transaction model. Instead, we have developed a general specification facility that enables the formalization of any transaction model that can be stated in terms of dependencies amongst significant events in different subtransactions. Such significant events include start, commit, and abort. We make no assumptions that these are the only kinds of events. Our approach is viable because most extended transaction models can be naturally formalized in terms of dependencies among different subtransactions.