Msting GUI btider technology supports btiding user interfaces for interactive applications via direct manip ulation.However, it is notoriously ~ctit to btid the underlying data sharing and application logic for rmdti-user synchronous co~aborative applications.This paper describes a co~ection of very high-levd software components, bfit using the JavaBeans component standard, that enables domain experts and application dsigners to rapi~y bfid entire co~aborative apphcatiorts via Visual progr arnming -drag-and~op, customization and wiring.Our component suite supports conference setup, awareness, data sharing, media streaming, acc~s synchronization, and tempordy coordinated media and event streams.TVe ~nstrate that the task of btiding non-trivia mdti-user applications using this approach is si@-tly s"np~ed. Ke~ordsRapid Application Devdopment, Visud"Rogramming, Software Components, Java Beans, ~en&Server Synchronous CoUaboration ~TRODUCTIONAs the use of distributed applications is becoming more widespread in today's networked world, the relevance of synchronous collaboration is sharply increasing.Users in a number of application domains are seeking syn-&onous co~aboration ~pabiities within their appfi-cation~.The requirements of this broad range of a~ p~cations me diverse enough that a 'one size fits d" approach to b@ding applications is no longer satisfactory.Our qerience suggests that rapid turnaround of customized co~aborative applications is critid to meet this incressed demand for synchronous co~aboration.Permission to make di~tal or hard copies of d] or part ofthis \\-orkfor personal or cl~aom use is granted without fee protided that copies are not made or dis~%uted for profit or commercial adv-antageand that copies bar this notice and tie fill citation on tie fmt paga To copy orhmlisa to Tepubtish.topost on swera or to rdlsmiute to ~sts, rquires prior ~etific permission and!or a f= CS~V 98 Sattle Ii'zshington GSA Cop~fight AChI 199S 1-5S1134094/9S/1 1...S5.00 . .

This paper describes algorithms for implementing a high-level programming model for synchronous distributed groupware applications. In this model, several application data objects may be atomically updated, and these objects automatically maintain consistency with their replicas using an optimistic algorithm. Changes to these objects may be optimistically or pessimistically observed by view objects by taking consistent snapshots. The algorithms for both update propagation and view notification are based upon optimistic guess propagation principles adapted for fast commit by using primary copy replication techniques. The main contribution of the paper is the synthesis of these two algorithmic techniques-guess propagation and primary copy replication-for implementing a framework that is easy to program to and is well suited for the needs of groupware applications.

This paper describes algorithms for implementing a high-level programming model for synchronous distributed groupware applications. In this model, several application data objects may be atomically updated, and these objects automatically maintain consistency with their replicas using an optimistic algorithm. Changes to these objects may be optimistically or pessimistically observed by view objects by taking consistent snapshots. The algorithms for both update propagation and view notification are based upon optimistic guess propagation principles, adapted for fast commit by using primary copy replication techniques. The main contribution of the paper is the synthesis of these two algorithmic techniques-guess propagation and primary copy replication-for implementing a framework that is easy to program and is well suited for the needs of groupware applications.