Tim Ewald, COM columnist for DOC Magazine, explains how COM+ works, and then sets out specific rules intended as concrete guidelines to help developers build COM+ systems.

The term “agent” is one of those catchwords that mean widely differing things to different people. To telecommunications people it is little more than a mobile piece of code that may be executed at any place. At the other extreme, AI people often associate with agents human-like traits such as social behavior. In between, software people view agents as fairly self-contained pieces of software that, at the low end, pretty much act like objects and, at the high end, more or less auto- mously decide when and how to react to stimuli or proactively initiate effects that can be observed from their environment. Software agents are particularly important when it comes to distributed en- ronments. There, much of the communication takes place asynchronously, that is the sequence of events cannot be planned ahead in all detail. Instead, agents are given rules as to how to interpret the current situation and, given a common goal, so that they adjust their response accordingly.

Developers need a way to interact with all data platforms in a uniform way, and Microsoft has attempted time and again to meet this need with its Universal Data Access strategy. In developing ADO.NET, Microsoft has made their additions of support for XML and disconnected data sets easier to use. This tutorial will guide the reader through ADO.NET from the top down, showing readers the hows and whys of using ADO.NET with lots of examples they can mold into their own projects right away. It is intended to be an introduction to ADO.NET for developers with some knowledge of data access. While it will show readers how ADO.NET follows on its predecessors, it will be written to avoid repeating any remedial instruction in databases and storage theory.

The advent of multicore processors has renewed interest in the idea of incorporating transactions into the programming model used to write parallel programs. This approach, known as transactional memory, offers an alternative, and hopefully better, way to coordinate concurrent threads. The ACI (atomicity, consistency, isolation) properties of transactions provide a foundation to ensure that concurrent reads and writes of shared data do not produce inconsistent or incorrect results. At a higher level, a computation wrapped in a transaction executes atomically - either it completes successfully and commits its result in its entirety or it aborts. In addition, isolation ensures the transaction produces the same result as if no other transactions were executing concurrently. Although transactions are not a parallel programming panacea, they shift much of the burden of synchronizing and coordinating parallel computations from a programmer to a compiler, to a language runtime system, or to hardware. The challenge for the system implementers is to build an efficient transactional memory infrastructure. This book presents an overview of the state of the art in the design and implementation of transactional memory systems, as of early spring 2010. Table of Contents: Introduction / Basic Transactions / Building on Basic Transactions / Software Transactional Memory / Hardware-Supported Transactional Memory / Conclusions

The advent of multi-core architectures and cloud-computing has brought parallel programming into the mainstream of software development. Unfortunately, writing scalable parallel programs using traditional lock-based synchronization primitives is well known to be a hard, time consuming and error-prone task, mastered by only a minority of specialized programmers. Building on the familiar abstraction of atomic transactions, Transactional Memory (TM) promises to free programmers from the complexity of conventional synchronization schemes, simplifying the development and verification of concurrent programs, enhancing code reliability, and boosting productivity. Over the last decade TM has been subject to intense research on a broad range of aspects including hardware and operating systems support, language integration, as well as algorithms and theoretical foundations. On the industrial side, the major players of the software and hardware markets have been up-front in the research and development of prototypal products providing support for TM systems. This has recently led to the introduction of hardware TM implementations on mainstream commercial microprocessors and to the integration of TM support for the world’s leading open source compiler. In such a vast inter-disciplinary domain, the Euro-TM COST Action (IC1001) has served as a catalyzer and a bridge for the various research communities looking at disparate, yet subtly interconnected, aspects of TM. This book emerged from the idea having Euro-TM experts compile recent results in the TM area in a single and consistent volume. Contributions have been carefully selected and revised to provide a broad coverage of several fundamental issues associated with the design and implementation of TM systems, including their theoretical underpinnings and algorithmic foundations, programming language integration and verification tools, hardware supports, distributed TM systems, self-tuning mechanisms, as well as lessons learnt from building complex TM-based applications.