Providing a shared memory abstraction in distributed systems is a powerful tool that can simplify the design and implementation of software systems for networked platforms. This enables the system designers to work with abstract readable and writable objects without the need to deal with the complexity and dynamism of the underlying platform. The key property of shared memory implementations is the consistency guarantee that it provides under concurrent access to the shared objects. The most intuitive memory consistency model is atomicity because of its equivalence with a memory system where accesses occur serially, one at a time. Emulations of shared atomic memory in distributed systems is an active area of research and development. The problem proves to be challenging, and especially so in distributed message passing settings with unreliable components, as is often the case in networked systems. We present several approaches to implementing shared memory services with the help of replication on top of message-passing distributed platforms subject to a variety of perturbations in the computing medium.

The papers present in this text survey both distributed shared memory (DSM) efforts and commercial DSM systems. The book discusses relevant issues that make the concept of DSM one of the most attractive approaches for building large-scale, high-performance multiprocessor systems. The authors provide a general introduction to the DSM field as well as a broad survey of the basic DSM concepts, mechanisms, design issues, and systems. The book concentrates on basic DSM algorithms, their enhancements, and their performance evaluation. In addition, it details implementations that employ DSM solutions at the software and the hardware level. This guide is a research and development reference that provides state-of-the art information that will be useful to architects, designers, and programmers of DSM systems.

Distributed Shared Memory (DSM) is one of the main approaches to implement distributed computing. The purpose of this project is to design and implement a prototype DSM that runs on popular TCP/IP networked Window PCs without special compliers and/or linkers. Our DSM uses lock based scope consistency (ScC), and supports central model, multiple server model and fully distributed model. We use object-oriented method to encapsulate these models within one framework. We provide C++ APIs and a DSM engine for C++ programmers to use DSM functions. The project is developed using C++ and Winsock APIs under Windows NT platform.

This book talks about the Specification and Verification of Distributed Shared Memory Relaxed Consistency Models specifically Weak Consistency Models. For this, an abstract Distributed Shared Memory (DSM) has been designed and implemented using CADP (Construction and Analysis of Distributed Processes). In DSM, sequential consistency unnecessarily reduces the performance of the system because it does not allow reordering or pipelining the memory operations. Weak consistency allows the reordering of memory events and buffering or pipelining of memory accesses so weak consistency improves the performance of the DSM system. For any critical system, it is very important to develop methods that increase our confidence in the correctness of such systems. One such method for the correctness of critical systems is formal verification. For verification of the weak consistency model, the properties of weak consistency have been specified and verified on the Abstract DSM System using CADP Toolbox.