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The Distributed Computing Environment (DCE) is a software system developed in the early 1990s by a consortium that included Apollo Computer (later part of Hewlett-Packard), IBM, Digital Equipment Corporation, and others. The DCE supplies a framework and toolkit for developing client/server applications. The framework includes a remote procedure call (RPC) mechanism known as DCE/RPC, a naming (directory) service, a time service, an authentication service and a distributed file system (DFS) known as DCE/DFS. DCE was a big step in direction to standardisation of architectures, which were manufacturer dependent before. Similar to the OSI model, DCE has not seen much success in practical implementation; however, its underlying concepts have had more substantial influence over subsequent efforts. ==History== Open Software Foundation (OSF) came about to a large degree as part of the Unix wars of the 1980s. After Sun Microsystems and AT&T Corporation worked together to produce UNIX System V Release 4 (SVR4) and refused to commit to fair and open licensing of Unix source code, many of the other Unix vendors felt their own market opportunities were unduly disadvantaged. The Distributed Computing Environment is a component of the OSF offerings, along with Motif and Distributed Management Environment (DME). As part of the formation of OSF, various members contributed many of their ongoing research projects as well as their commercial products. For example, HP/Apollo contributed its Network Computing Environment (NCS) and CMA Threads products. Siemens Nixdorf contributed its X.500 server and ASN/1 compiler tools. At the time, network computing was quite popular, and many of the companies involved were working on similar RPC-based systems. By integrating security, RPC and other distributed services on a single "official" distributed computing environment, OSF could offer a major advantage over SVR4, allowing any DCE-supporting system (namely OSF/1) to interoperate in a larger network. The DCE system was, to a large degree, based on independent developments made by each of the partners. DCE/RPC was derived from the ''Network Computing System'' (NCS) created at Apollo Computer. The naming service was derived from work done at Digital. DCE/DFS was based on the Andrew File System (AFS) originally developed at Carnegie Mellon University. The authentication system was based on Kerberos, and the authorization system based on Access Control Lists (ACLs). By combining these features, DCE offers a fairly complete C-based system for network computing. Any machine on the network can authenticate its users, gain access to resources, and then call them remotely using a single integrated API. The rise of the Internet, Java and web services stole much of DCE's mindshare through the mid-to-late 1990s, and competing systems such as CORBA muddied the waters as well. One of the major uses of DCE today is Microsoft's DCOM and ODBC systems, which use DCE/RPC (in MSRPC) as their network transport layer. OSF and its projects eventually became part of The Open Group, which released DCE 1.2.2 under a free software license (the LGPL) on 12 January 2005. DCE 1.1 was available much earlier under the OSF BSD license, and resulted in FreeDCE being available since 2000. FreeDCE contains an implementation of DCOM. 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「distributed computing environment」の詳細全文を読む スポンサード リンク
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