2.2. Defining the Architecture A Netnews system is a distributed database composed of "agents" of various types which, acting together according to the protocols defined in section 7 of this standard, causes articles to be propagated throughout the system and to be made available to its readers. The protocols ensure that all copies of a given article, wherever stored, are identical apart from those headers defined as variant (a-4.2.5.3). A "posting agent" is the software that assists posters to prepare proto-articles in compliance with [USEFOR]. The proto-article is then passed on to an "injecting agent" for final checking and injection into the news stream. If the article is not compliant, or is rejected by the injecting agent, then the posting agent informs the poster with an explanation of the error. A "reading agent" is software which presents articles to a reader. A "followup agent" is a combination of reading agent and posting agent that aids in the preparation and posting of a followup. [Alternative definition, to be used if the alternative definition for "followup" is used:] A "followup agent" is a combination of reading agent and posting agent that aids in the preparation and posting of a response intended as a followup to a precursor. An "injecting agent" takes the finished article from the posting agent (often via the NNTP "POST" command), performs some final checks and passes it on to a "relaying agent" for general distribution. It is expected to bear some responsibility towards the rest of the network for the behaviour of its posters (and provision is therefore made for it to be easily contactable by email). A "relaying agent" is software which receives allegedly compliant articles from injecting agents and/or other relaying agents, and possibly passes copies on to other relaying agents and "serving agents". A "serving agent" receives an article from a relaying agent and files it in a "news database". It also provides an interface for reading agents to access the news database. A "news database" is the set of articles and related structural information stored by a serving agent and made available for access by reading agents. A "gateway" is software which receives news articles and converts them to messages of some other kind (e.g. mail to a mailing list), or vice versa; in essence it is a translating relaying agent that straddles boundaries between different methods of message exchange. The most common type of gateway connects newsgroup(s) to mailing list(s), either unidirectionally or bidirectionally, but there are also gateways between news networks using this standard's news format and those using other formats. Posting, reading and followup agents (which are usually just different services provided by the same piece of software) are known collectively as "user agents".[< Prev] [TOC] [ Next >]
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