Kevan Lee Miller

Concurrency control and view notification algorithms for collaborative replicated objects

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.

Rapidly building synchronous collaborative applications by direct manipulation

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.

Experiences with building distributed debuggers

In this paper, we report on our experiences in building debuggers for distributed applications. We begin by presenting a number of important issues that are encountered in building distributed debuggers and briefly describe our approach to addressing them. Next, we outline a set of debugging functions that our debugger supports. We then describe the architecture of our latest prototype. The prototype supports the debugging of multi–threaded, multiprocess, multi-language applications that use multiple middlewares while executing in a heterogeneous distributed environment. Finally, we describe the implementation of some of the distributed primitives that make our debugger particularly suited to debugging distributed applications.