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Isis2 is a BSD-licensed distributed computing library written in C# and callable from programs coded in any language supported on .NET on Windows, such as C#, C++/CLI, F#, IronPython and IronRuby. The system can also be used on Linux systems by compiling it under Mono, which supports C# and IronPython. It provides a wide variety of distributed computing abstractions, including state machine replication, fault-tolerant process groups, atomic broadcast with several levels of ordering and durability, a distributed lock manager, persistent replicated data, a distributed key-value store (also called a Distributed Hash Table or DHT), and scalable aggregation. The system implements the virtual synchrony execution model, and includes an implementation of Leslie Lamport's Paxos Protocol. Isis2 is an object oriented software library, in which the developer uses a local object as an endpoint associated with a fault-tolerant group, and receives events such as notifications of membership changes (joins, leaves, failure) or data updates via event upcalls. If desired, Isis2 process groups can be secured. When this feature is employed, all communication within a group is encrypted using AES 256-bit keys and all non-group messages are signed with SHA 256-bit signatures. The required keys can be held in any standard certificate authority and supplied by the application, or can be generated automatically when the group is first created, and stored in the file system by the Isis2 library (in the latter case, the file system access control system is trusted to prevent unauthorized key use). Isis2 is actually the fourth in a series of Cornell-developed software libraries for reliable multicast that share many design features. The first was the Isis Toolkit, developed in 1985 and ultimately used in the New York Stock Exchange, the French Air Traffic Control System, the US Navy AEGIS and other settings.〔(【引用サイトリンク】 author = Ken Birman )〕 Subsequent generations of the technology included the Horus System and the Ensemble System.〔(【引用サイトリンク】 author = Xiaoming Liu, Christoph Kreitz, Robbert van Renesse, Jason Hickey, Mark Hayden, Ken Birman, and Robert Constable. )〕 The Isis Toolkit, introduced the virtual synchrony model, but was coded in C with limited support for more modern programming paradigms. Horus and Ensemble innovated structurally: these systems also offered virtual synchrony, but showed how the protocols could be implemented by composition of microprotocols. Ensemble was written in OCaml and could be formally analyzed using the Nuprl program refinement logic and theorem proving tool. Isis2 departs from the sequence by focusing on modern object orientation, type checking and modularity features. The system is also targeted at large scale use cases, including scenarios seen in cloud computing systems, where strong consistency might be useful both in the first tier "soft state" layer and in back-end systems. Isis2 was initially released in 2013, with periodic updates and revisions since that time. The most current stable release is V2.2.2013; it was released on July 15, 2015. The prior stable release was downloaded more than 750 times. In 2015 work began on a new system called DMC (Derecho Multicast) that will be optimized for networks supporting RDMA zero-copy data transfers.〔(【引用サイトリンク】title=Starting work on a new native C++ version of Isis2 )〕 A secondary goal that DMC be implemented in C++ 11 was tabled in August 2015 over concerns that the mix of C++ 11 with DMC might be overly complex and for this reason, unpopular.〔(【引用サイトリンク】title=DMC in pure C++: Tabled, for now, although you can certainly use the system from C++ )〕 ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Isis2」の詳細全文を読む スポンサード リンク
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