Supporting disconnection operations through cooperative hoarding

Mobile clients often need to operate while disconnected from the network due to limited battery life and network coverage. Hoarding supports this by fetching frequently accessed data into clients' local caches prior to disconnection. Existing work on hoarding have focused on improving data accessibility for individual mobile clients. However, due to storage limitations, mobile clients may not be able to hoard every data object they need. This leads to cache misses and disruption to clients' operations. In this paper, a new concept called cooperative hoarding is introduced to reduce the risks of cache misses for mobile clients. Cooperative hoarding takes advantage of group mobility behaviour, combined with peer cooperation in ad-hoc mode, to improve hoard performance. Two cooperative hoarding approaches are proposed that take into account access frequency, connection probability, and cache size of mobile clients so that hoarding can be performed cooperatively. Simulation results show that the proposed methods significantly improve cache hit ratio and provides better support for disconnected operations compared to existing schemes

Knowledge-driven Interactions With Services Across Ad Hoc Networks

Service oriented computing, with its aim of unhindered in-teroperability, is an appropriate paradigm for ad hoc net-works, which are characterized by physical mobility of het-erogenous hosts and by the absence of standardized application level protocols. The decoupled nature of computing in ad hoc networks can result in disconnections at inoppor-tune times during the client-service interaction process. We introduce the notion of a priori selection of services to reduce the likelihood of disconnection during service usage. A client may specify the times when it requires certain ser-vices. A knowledge base of the physical motion profiles of various service providers is used to select instances of a ser-vice that are co-located with the client at the required time and least likely to disconnect. A system for constructing the knowledge base is presented in this paper, along with the implementation details and the algorithm used to deter-mine the service usage pattern

FEW : file management for portable devices

Comunicação apresentada ao International Workshop on Software Support for Portable Storage (IWSSPS), San Francisco, 2005.In recent years, an increasing number of portable devices with large amounts of storage have become widely used. In this paper, we present the early design of the FEW system, a system that aims to ease file management in the new mobile environment. To this end, the system will manage file replicas stored in fixed and portable storage devices. It will provide an automatic mechanism to establish new file replicas by analyzing file system activity. The system will automatically and incrementally synchronize all file replicas exploring the available network connectivity and the availability of portable storage devices. To merge concurrent updates, operational transformation techniques will be used.FCT/MCES POSI/FEDER - Project #59064/2004

Bringing Light to the Unconscious: A Theoretical Examination of Racism Through the Adlerian Lens of Social Interest

This theoretical paper posits that racial oppression ensues in part due to a lack of social interest, manifested by excessive self-interest in the projection of negative white attributions onto people of color. Excessive white self-interest not only divides whites and Black people but within people groups and among individuals; all are negatively impacted by racism, and to believe otherwise is to succumb to the dangerous falsity of zero-sum thinking. Furthermore, a scholarly case is made for the amplification of social interest by a lowering of white defenses and a reclamation of one’s authentic parts of self. Specifically, one must acknowledge, claim, and examine internalized white power structures, which denote ways of thinking, feeling, and being that uphold white superiority and nullify relationships of equity which welcome all parts of the self. In examining one’s defenses and the vulnerability behind them, one can hope to re-engage in a more wholesome and healthy way that prioritizes shared power relationships instead of power over relationships (Hill, 2022). This process is often ambiguous, nonlinear, personal, and subjective; it is a personal kind of learning.social interest, feelings of inferiority, racism, the gaze, dysconsciousness, decolonization of psycholog

Dynamic contention management for distributed applications

PhD ThesisDistributed applications often make use of replicated state to afford a greater level of availability and throughput. This is achieved by allowing individual processes to progress without requiring prior synchronisation. This approach, termed optimistic replication, results in divergent replicas that must be reconciled to achieve an overall consistent state. Concurrent operations to shared objects in the replicas result in conflicting updates that require reconciliatory action to rectify. This typically takes the form of compensatory execution or simply undoing and rolling back client state. When considering user interaction with the application, there exists relationships and intent in the ordering and execution of these operations. The enactment of reconciliation that determines one action as conflicted may have far reaching implications with regards to the user’s original intent. In such scenarios, the compensatory action applied to a conflict may require previous operations to also be undone or compensated such that the user’s intent is maintained. Therefore, an ability to manage the contention to the shared data across the distributed application to pre-emptively lower conflicts resulting from these infringements is desirable. The aim is to not hinder throughput, achieved from the weaker consistency model known as eventual consistency. In this thesis, a model is presented for a contention management framework that schedules access using the expected execution inherent in the application domain to best inform the contention manager. A backoff scheme is employed to create an access schedule, preserving user intent for applications that require this high level of maintenance for user actions. By using such an approach, this results in a performance improvement seen in the reduction of the overall number of conflicts, while also improving overall system throughput. This thesis describes how the contention management scheme operates and, through experimentation, the performance benefits received