/[webpac]/openisis/current/doc/Config.txt
This is repository of my old source code which isn't updated any more. Go to git.rot13.org for current projects!
ViewVC logotype

Contents of /openisis/current/doc/Config.txt

Parent Directory Parent Directory | Revision Log Revision Log


Revision 237 - (show annotations)
Mon Mar 8 17:43:12 2004 UTC (16 years, 7 months ago) by dpavlin
File MIME type: text/plain
File size: 3740 byte(s)
initial import of openisis 0.9.0 vendor drop

1 accessing configuration data
2
3 * overview
4
5 Conceptually, all configuration data is bound to a database.
6 Databases are organized in SCHEMAS,
7 with one schema representing local databases
8 and other schemas corresponding to remote server stubs.
9 While many configuration options may be treated likewise
10 for local and remote schemas, some options, such as file paths,
11 are meaningful only within the local schema
12 and should not be distributed by servers.
13
14
15 * schema and database access
16
17 Schemas are accessed by either names or numbers (one byte),
18 the local schema has empty name and number 0.
19 A remote schema's name may be an URL like "host" or "host:port"
20 (possibly one day even with protocol like "z3950://...")
21 or a symbolic name, typically referring to some local
22 configuration source for host and other parameters.
23
24 Within each schema, databases are accessed by either
25 simple names like "cds" or numbers (two bytes).
26 A main entry with empty name and number 0 holds options which
27 are global to a schema and/or serve as defaults for databases.
28
29
30 In addition to the configuration data,
31 each schema entry may contain data related to the actual implementation,
32 e.g. file id's for a local database or sockets in a remote schema's
33 main entry.
34
35
36 * configuration parameters
37
38 A database's configuration can for the most part be considered one record
39 with nested subrecords.
40 For efficient access, however, several logical subrecords may
41 be available as records on their own and/or in a parsed representation.
42
43 A configuration entry includes
44 - general parameters record
45 These include traditional standard system and database parameters,
46 encoding names, named texts to be interpreted as "printformats" (PFT)
47 and so on. This record's metadata is
48 > Builtin
49 - a parsed version of the FDT
50 - a parsed version of the FST
51 - optional character tables
52 These are corresponding to the ISISAC.TAB,
53 > http://www.cindoc.csic.es/isis/21-5.htm ISISUC.TAB, SRT-files
54 and recoding tables as of
55 > Syspar
56 106, 107.
57 - optional named views
58 The sort of "printformat" acting as database views.
59 - stopword list (STW)
60
61 Several of these are used only for indexing and thus
62 are usually not needed in a remote database description.
63
64 Some environments may use additional data like work sheets (FMT).
65
66
67 * implementation notes
68
69 - mapping of names to numbers is relative to each process.
70 between processes, only names may be exchanged.
71 - most ressources are accessed using defaulting,
72 i.e. if a parameter is not found in the entry of a given database,
73 it is searched for in the schema's main entry.
74 - in the traditional (WinISIS) implementation of local schema
75 configuration data, named PFTs, FMTs and other are looked up as files,
76 which are not actually relative to a database, but to either
77 the schema's standard directory or a tool directory as of dbname.par 10.
78 While the sharing of such ressources in the standard directory
79 corresponds to placing them in a schema's main entry,
80 other --possibly shared-- tool directories will (some day)
81 be implemented by additional database entries,
82 which may be referred to by other databases.
83
84
85 * synchronization
86
87 All configuration ressources can be modified only
88 by the default session.
89 Other sessions can assume them to be immutable
90 for the lifetime of one request.
91
92 If the default session wants to change a configuration,
93 the database has to be remounted in single user mode,
94 inaccessible to other sessions.
95 This might involve some waiting for other sessions
96 to finish their current request.
97
98
99 To support this, each database entry has a mount status and a
100 count of sessions using it (not counting the default session).
101
102 For details see the paper on
103 > Concurrency
104 .
105
106
107 ---
108 $Id: Config.txt,v 1.3 2003/02/13 16:58:45 kripke Exp $

  ViewVC Help
Powered by ViewVC 1.1.26