The HiPAC (High Performance ACtive database system) project addresses two critical problems in time-constrained data management: the handling of timing constraints in databases, and the avoidance of wasteful polling through the use of situation-action rules that are an integral part of the database and are monitored by DBMS's condition monitor. A rich knowledge model provides the necessary primitives for definition of timing constraints, situation-action rules, and precipitating events. The execution model allows various coupling modes between transactions, situation evaluations and actions, and provides the framework for correct concurrent execution of transactions and triggered actions. Different approaches to scheduling of time-constrained tasks and transactions are explored and an architecture is being designed with special emphasis on the interaction of the time-constrained, active DBMS and the operating system. Performance models are developed to evaluate the various design alternatives.

Data sharing is fundamental to computer-supported cooperative work: 'people share information through explicit communication channels and through their coordinated use of shared databases.Database support tools are therefore critical to the effective implementation of software for group work. This paper surveys data sharing requirements for group work, h~ghlighti~g new database technologies that are especially likely to affect our ability to build computei" systems supporting group work.

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usiness-to-business integration is transforming the market and has already begun to increase the efficiency of those companies involved. The first step, integration of data, began with Electronic Data Interchange (EDI) in the 1980s. The second step, integration of process information, is only now beginning to emerge. Consider a fictitious company, Acme Manufacturing, that ships its products via Federal Express. In the past, Acme used a dedicated computer with proprietary software to arrange pickups directly from Federal Express. Today Acme can use the Federal Express website to arrange for shipment and to follow a package's progress in real time. Acme can check whether the package has been delivered to the station, transported to the destination city, delivered to the addressee, or signed for at its final destination. By making process information available through the Web, Federal Express does not need a support department to give this information over the phone. If Acme wants to order a computer from Dell Computer Corporation, it can do so through the Dell website. Acme can also track the order's progress through five stages: order processing, preproduction, production, delivery prep, and shipping. Again, making this simplified external view of their internal order fulfillment processes available over the Web saves Dell the expense of answering status questions over the phone. Say Dell subcontracts delivery to Airborne Express, a firm with a similar Web interface. Once the Dell process reaches the shipped state, users can follow a link directly to the Airborne website, which gives additional detail about the shipment status. ENABLING E-BUSINESS WORKFLOW Many companies (such as the examples cited above) have shown that providing process status in a user-readable form over the Web is valuable to business. There is an additional value to be gained from providing that information in a machine-readable form.

Data sharing is fundamental to computer-supported cooperative work: People share information through explicit communication channels and through their coordinated use of shared databases. This paper examines the data management requirements of group work applications on the basis of experience with three prototype systems and on observations from the literature. Database and object management technologies that support these requirements are briefly surveyed, and unresolved issues in the particular areas of access control and concurrency control are identified for future research.