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DX 200 is a digital switching platform currently developed by Nokia Networks. == Architecture == DX 200 is a versatile, fault-tolerant, modular and highly scalable telephone exchange and general purpose server platform, designed for high performance, high availability applications. Its hardware is built from loosely coupled redundant computer units, backed by distributed software architecture. Architecture of DX 200 allows live migration as well as software update during live operation. Unlike in many other switching platforms, DX 200 performs live software update without code patching. Therefore, running code is not polluted by unnecessary jump instructions. Furthermore, as opposed to "integration guessing" of various software patches, DX 200 architecture makes proper integration testing of software components possible. Live software update requires two computer units. One executing the old code ("working"), the other with new software loaded, otherwise idle ("spare"). During the process called "warming" memory areas (e.g. dynamically allocated memory, with the exception of stack of procedures) are moved from the old to the new computer unit. That implies that handling of data structures must be compatible in the old and the new software versions. Copying data does not require any programming effort, as long as allocation of data is done using TNSDL language. Developing software for DX 200 platform is rather straightforward for any well educated software developer. TNSDL language, which plays vital role in producing asynchronously communicating fault-tolerant software modules, is easy to learn. Software architecture of DX 200 is a fine combination of highly efficient traditional solutions as well as modern actor model based, highly concurrent design. DX 200 products are famous for availability exceeding 99.999% "five nines" as well as unrivaled performance. 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「Nokia DX 200」の詳細全文を読む スポンサード リンク
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