Ficus is a exible replication facility with optimistic concurrency control designed to span a wide range of scales and network environments. Support for partitioned operation is fundamental to the Ficus design but was not widely exercised in early Ficus use. This position paper reports recent experiences using Ficus in settings where some replicas are only occasionally connected to a network, a...

In addition to satisfying data consistency requirements as in conventional database systems, concurrency control in real-time database systems must also satisfy timing constraints, such as deadlines associated with transactions. Concurrency control for a real-time database system can be studied from several different perspectives. This largely depends on how the system is specified in terms of ...

Ficus is a flexible replication facility with optimistic concurrency control designed to span a wide range of scales and network environments. Optimistic concurrency control provides rapid local access and high availability of files for update in the face of disconnection, at the cost of occasional conflicts that are only discovered when the system is reconnected. Ficus reliably detects all pos...

The advent of information systems based on the World Wide Web increased the impact of concurrent programs. Such increase demands the definition of methods for obtaining safe and efficient implementations of concurrent programs, since the complexity of implementation and tests in concurrent environments is higher than in sequential environments. This paper presents a simple framework that helps ...

As web–based information systems usually run in concurrent environment, the complexity for implementing and testing those systems is significantly high. Therefore it is useful to have guidelines to introduce concurrency control, avoiding ad hoc control strategies, which may have a negative impact in efficiency and may not guarantee system safety. This paper defines guidelines for concurrency co...

EEcient distributed concurrency control is one of the most signiicant challenges in building real-time cooperative editing systems. In this paper , we focus on the deenition and veriication of an integrated set of distributed concurrency control schemes based on a novel consistency model for solving three inconsistency problems: divergence, causality-violation, and intention-violation in real-t...

The multidatabase system(MDBS) has a global database, a set of global and local transactions, and a global transaction manager(GTM) which is built on top of a number of pre-existing database management systems(DBMS) that are being integrated into a single MDBS. The global transaction manager has the responsibility for maintaining the global consistency of MDBS. It is impossible for LDBSs to pre...

In a real-time database system, it is difficult to meet all timing constraints due to the consistency requirements of the underlying database. However, when the transactions in the system are heterogeneous, they are not of the same importance some are of greater importance than others. In this paper, we propose a new optimistic concurrency control protocol called OCC-PDATI which uses informatio...

In order to increase availability in a distributed system some or all of the data items are replicated and stored at separate sites. This is an issue of key concern especially since there is such a proliferation of wireless technologies and mobile users. However, the concurrent processing of transactions at separate sites can generate inconsistencies in the stored information. We have built a d...

In a recent study, we have shown that in real-time database systems that discard late transactions, optimistic concurrency control outperforms locking. Although the optimistic algorithm used in that study, OPT-BC, did not factor in transaction deadlines in making data conflict resolution decisions, it still outperformed a deadline-cognizant locking algorithm. In this paper, we discuss why addin...