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1 -------------------------------------------------------------------------------
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2 NOFFLE Internals
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3 -------------------------------------------------------------------------------
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4
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5 This document is, for the moment, a collection of jottings on aspects
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6 of Noffle internals.One day it might make it into something resembling
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7 documentation, but I wouldn't put your money on it. Use the Source,
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8 Luke!
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9
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10 1. Where do things get stored?
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11
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12 Articles: Articles are held keyed by Message-ID in the articles
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13 database, articles.gdbm. This is handled by database.[hc]. Articles
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14 are marked with a status, indicating if they were only partially
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15 downloaded (think overview mode) or if something went wrong on
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16 retrieval.
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17
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18 Groups: The list of groups known is held in the groups database,
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19 groupinfo.gdbm, keyed on group name. This holds the group first and
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20 last article numbers, the last article number read on the remote
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21 server, group creation and last access times, plus the group
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22 description, the name of the server from which the group is drawn and
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23 a flag indicating if posting to the group is allowed.
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24
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25 Local groups are indicated as belonging to a special server. They are
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26 for the most part treated identically to remote groups (though the
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27 whole business of auto-subscribe and auto-unsubscribe obviously
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28 doesn't apply, and posting operates locally).
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29
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30 The fetchlist (fetchlist.[hc]) holds the list of group names Noffle
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31 currently subscribes to, and the subscription mode.
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32
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33 Subscribed groups may have a file with their name in the overview
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34 directory. This file - the overview file - contains details of the
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35 articles in the group that can currently be read from the server. Each
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36 entry in the file is an overview (over.[hc]), while a group overview
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37 file is handled by content.[hc]. If no articles are left in a group,
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38 the overview file is deleted.
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39
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40 The Noffle server loads the overview for a group into memory when it
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41 needs to manipulate the group and uses its reckoning on the first and
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42 last article number from there on. This may not correspond with the
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43 first and last number given in the groups database entry. Typically,
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44 the database first and last entries are updated from the overview on
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45 completion of actions affecting the group.
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46
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47 Outbound articles are placed in a directory under the Noffle spool
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48 'outgoing' directory. Each is in its own file, named by the article
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49 Message-ID, in a directory with the name of the server. outgoing.[hc]
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50 handle tracking what outbound messages are queued and queueing new ones.
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51 When Noffle connects to the appropriate server, the message is posted
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52 on and the file removed.
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53
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54 2. Posting
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55
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56 Posting to remote groups is straightforward; the article is placed in
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57 the outgoing queue, and will be read back from the server as part of
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58 collecting new messages for the group. The article is placed once only
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59 in the queue, regardless of the number of external groups, as it only
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60 needs to appear once on the remote server. Articles posted only to
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61 newsgroups unknown to Noffle are rejected.
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62
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63 If the group is marked as 'can't post' ('n' in LIST ACTIVE) the post
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64 is rejected immediately. Note you can't have moderated local groups at
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65 the moment; you can have read-only ones, though.
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66
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67 Control message are similarly passed on, unless the control is
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68 'cancel' and the cancel can be done entirely locally because the
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69 article is still in the outgoing queue.
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70
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71 Posts to local groups appear in the article database
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72 immediately. Control messages (control.[hc]) for local groups are
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73 honoured, though currently only 'cancel' does anything.
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74
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75 Things get more complex when an article is cross-posted to a local and
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76 remote group. Essentially, both the above happen; if the remote server
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77 does not change the Message-ID, the local copy will be the definitive
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78 for both groups. Obviously if the remote server does change the
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79 Message-ID, Noffle will tread the article coming back from the server
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80 as a new one.
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81
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82 post.[hc] holds the code for posting local articles.
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83
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84 The posting code in post 1.0 Noffle should (i.e. I'll do it if time
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85 permits) be rearranged to provide one function to post (or reject) an
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86 article regardless of original source. This would hopefully make it
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87 clearer what happens during a post, and make it easy to add a
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88 command-line article post function, which could remove the necessity
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89 for Python or Perl intervention gateing mailing lists into local newsgroups.
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90
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91 3. Pseudo articles
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92
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93 Noffle generates various pseudo articles itself (see pseudo.[hc]), to
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94 inform the user of changes of state or to give instruction. All but
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95 one are, in fact, done by generating and posting a regular article,
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96 but one is special; the general information article.
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97
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98 The gen info article is the one shown when one tries to read from a
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99 currently unsubscribed (Noffle is not subscribed to it, that it)
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100 newsgroup. It is apparently present in every single group known to
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101 Noffle, but is faked; it never appears in the article database. LIST
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102 ACTIVE fakes the first and last article numbers for a group if it
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103 knows the group is not subscribed to (and not local), and entry to a
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104 group with the GROUP command will cause an overview to be added to the
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105 group overview in memory only. If the article is not read, the
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106 overview is lost unsaved when moving to the next group.
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107
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108 Reading the article triggers stuff happening. If auto-subscribe is on,
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109 a pseudo article confirming subcription is posted and the group
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110 overview saved. Gen info articles are not normally saved in overviews,
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111 but to prevent them vanishing very suddenly their overview is saved
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112 with other articles in the group if they form part of the sequence of
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113 the group. In this case it will persist until the subscription confirm
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114 article expires. This will not stop another gen info being generated
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115 if (say) the group gets auto-unsubscribed.
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