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State Machine Replication (SMR) is a well-known technique to implement fault-tolerant systems. In SMR, servers are replicated and client requests are deterministically executed in the same order by all replicas. To improve performance in multi-processor systems, some approaches have proposed to parallelize the execution of non-conflicting requests. Such approaches perform remarkably well in workloads...
In this paper we present a new approach to implementing causal consistency in geo-replicated data stores, which we call Optimistic Causal Consistency (OCC). The optimism in our approach lies in that updates from a remote data center are immediately made visible in the local data center, without checking if their causal dependencies have been received. Servers perform the dependency check needed to...
Parallel file systems are often characterized by a layered architecture that decouples metadata management from I/O operations, allowing file systems to facilitate fast concurrent access to file contents. However, metadata intensive workloads are still likely to bottleneck at the file system control plane due to namespace synchronization, which taxes application performance through lock contention...
High frequency trading (HFT) environments provide technologies that enable algorithmic trading within automated marketplaces. The most prominent example of an HFT environment is within equity trading, where many millions of trades are achieved at a high volume to gain a reasonable cumulative profit. Such environments rely on low latency/high performance technologies to allow trades to react in a timely...
Mobile data usage is on a tremendous rise, due not only to increasing number of users but also to an increase in the number of applications that transfer data over the network. Moreover, applications for sharing, sensing, and collaboration have become more popular, causing significant amounts of data to be generated on devices. Managing this data -- syncing it to the cloud, or with other users or...
Architecture Description Languages (ADLs) were developed to support the abstract level of software structuring that is the subject matter of software architecture. Community is an ADL built on co-ordination principles and a categorical framework to support the composition of specifications of components to form the system's specification. However, an important shortcoming of Community is the lack...
To store and manage data efficiently is the critical issue which modern information infrastructures confront with. To accommodate the massive scale of data in the Internet environment, most common solutions utilize distributed file systems. However there still exist disadvantages preventing these systems from delivering satisfying performance. In this paper, we present a Name Node cluster file system...
Process algebra for quantitative evaluation are based on either of the two following mechanisms for communication: binary, where a channel is shared by exactly two agents, or multiway, where all agents sharing a channel must synchronise. In this paper we consider an intermediate form which we call generalised communication, where only m agents out of n potentially available are involved in the communication...
With more and more personal data being collected and stored by service providers, there is an increasing need to ensure that their usage is compliant with privacy regulations. We consider the specific scenario where policies are defined in metric temporal logic and audited against the database usage logs. Previous works have shown that this can indeed be achieved in an efficient manner for a very...
Fluidization is an efficient relaxation technique to tackle classical state explosion problems in discrete event systems (DES), which consists in approximating the discrete states by some continuous or hybrid ones. This is not a technical work in the most classical sense. More epistemological and methodological, the purpose is to overview fluidization in several well-known modeling paradigms for DES...
LDAP Multi-Master Technique is a replication approach using Syncrepl to replicate data to multiple servers. As the specialized database optimized for read access, the directory is used to represent heterogeneous entities in directory information tree (DIT). Compared with existing Sync replication models, the directory template replication model based on query templates proposed in this paper only...
One of the principal goal of Component-Based Software Engineering (CBSE) is to allow the reuse of components in diverse situations without affecting their codes. To reach this goal, it is necessary to propose approaches to adapt a component with its environment when behavioural mismatches occur during their interactions. In this paper, we present a formal approach based on interface automata to adapt...
In order to circumvent the problem of state-space explosion of large-scale Markovian models, the stochastic process algebra PEPA has been given a fluid semantics based on ordinary differential equations, treating all entities as continuous. However, low numbers of instances and/or relatively slow dynamics may make such approximation too coarse for some parts of the system. To deal with such situations,...
Nowadays, the problem in business process management (BPM) is that BPM systems should both be easy to use for business process developers and be based on a sound formal method. Business process management systems are often based on semiformal modeling techniques such as event-driven process chains (EPC) or UML. Unlike semiformal modeling techniques, the process calculus CSP comes with mature verification...
Design applications, e.g., CAD or media production, often require multiple users to work cooperatively on shared data, e.g., XML documents. Using explicit transactions in such environments is difficult, because designers usually do not want to consider transactions or ACID. However, applying transactions in order to control visibility of changes or specify recovery units, is reasonable, but determining...
In this paper we describe a novel Model-View-Controller based architecture, Centralized Control, that introduces collaboration in single-users applications. The architecture is able to add collaboration with no need to modify the source code of the original single-user application, and providing also the capability to introduce group semantics into the new, collaborative application that is obtained...
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