/[A3C]/lib/A3C.pod
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Contents of /lib/A3C.pod

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Fri Jun 20 12:27:13 2008 UTC (11 years ago) by dpavlin
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1 =head1 NAME
2
3 A3C = AAAC; AAA from "Authentication, Authorization and Accounting" and C from "CARNet".
4
5 =head1 DESCRIPTION
6
7 This page describes general idea about A3C application and current status of implementation.
8
9 Opinions should be attributed to Dobrica Pavlinusic, and not other developers :-)
10 It's supposed to convey a story which is coherent enough for new developer
11 to join into project. Most of other documentation is more useful when
12 developing and looking into code usage (if it's not documented and tested,
13 it doesn't exist) but this part is delivered as pure POD for reading pleasure.
14
15 =head1 Models
16
17 Models in Jifty are at perl level objects (with validation and
18 canonicalization) and tables in database.
19
20 For a start, we implement some magic documented in L<A3C::Record> on records
21 (rows in database).
22
23 Then, we need to mungle data without re-thinking SQL queries which would
24 produce same results, so there is L<A3C::SQL> which produce objects that
25 look like L<Jifty::Collection>s, but aren't. This allows us to switch into
26 SQL in views if needed.
27
28 This method is not perfect, and shouldn't be used instead of Jifty models
29 just to write SQL because it doesn't do any permission checking. However,
30 it's a huge help for complex C<GROUP BY> and C<JOIN> queries which are hard
31 to express using L<Jifty::DBI>.
32
33 If we needed to generate those queries from within program (from user data,
34 for example) something like L<Fey::SQL> would be much better tool.
35
36 =head1 LDAP
37
38 Implement LDAP entry and edit interface (interesting problem since most
39 entries can have multiple values which doesn't map nicely to relational
40 schema).
41
42 This task can be broken down into following parts:
43
44 =head2 Multiple values
45
46 When creating records with ARRAY values L<A3C::Record/create>
47 joins values with magic marker between them to make rest of Jifty happy.
48
49 Plan is to use full-text search engine to search over data anyway, so this
50 is not serious limitation. If needed, something like bitmap indexes could be
51 used at database level to expose those values for filtering. For joins we
52 would probably need separate materialized many-many tables which could be
53 created more-or-less automatically in L<A3C::Record>.
54
55 =head2 Import data from existing LDAP server
56
57 C<bin/import-ldap.pl> has embedded documentation and uses L<A3C::LDAP>
58
59 L<http://a3c.skole.hr/ldap/> is user interface to L<A3C::View::LDAP> and
60 L<A3C::Action::SyncOrganization>
61
62 =head2 Query existing LDAP server
63
64 Since we are creating local copy of data, we need easy way to ask master
65 LDAP server for data. L<A3C::LDAP> provides way to query LDAP and receive
66 something similar enough to L<Jifty::Collection> so that L<A3C::View>s
67 doesn't have to be edited to switch from Jifty models to LDAP
68 data.
69
70 =head2 Create new entries and edit existing ones
71
72 We are in the middle of migration from (generic) L<A3C::Model::Person> and
73 L<A3C::Model::Organization> to our custom L<A3C::Model::hrEduOrg> and
74 L<A3C::Model::hrEduPerson>
75
76 Most views I guess, will be implemented by sub-classing L<Jifty::View::Declare::CRUD>.
77 Right now L<A3C::View::Organization> is such implementation.
78
79 Planned C<A3C::View::hrEduPerson> will implement another such view, and I
80 hope to see some kind of code reuse there (which should probably move to
81 C<Jifty::Plugin::TableCRUD>).
82
83 =head2 Virtual LDAP server to publish data
84
85 This part is in planning stage, and it will probably be based on L<Net::LDAP::Server>.
86
87 =head1 Existing LDAP schema
88
89 First, we needed a clever way to import existing LDAP schema into Jifty. So,
90 C<bin/ldap2model.pl> helper was created to handle that.
91
92 Some entries in LDAP schema have fixed list of attributed, and L<A3C::AAIEduHr>
93 implements fetcher (with cache) for that data.
94
95 =head1 Legacy portal integration
96
97 =head2 Parse PHP config files
98
99 Configuration files in PHP is only place in which part of portal
100 configuration is specified. To handle it in A3C, we use
101 L<A3C::Model::StrixInstance> which aggregates all instance data. Parser is
102 implemented by L<A3C::PHP>
103
104 =head2 Connect to remote database
105
106 Implemented in two different ways:
107
108 =head3 Direct SQL execution
109
110 L<A3C::Action::StrixSQL> and interface as L<A3C::View::Strix/sql>.
111
112 =head3 Fetching data hashes
113
114 C<Strix> (which doesn't link well from on-line documentation so you will
115 have to take a look in C<lib/Strix.pm>) implements pure DBI code (ported
116 from php) to access data directly. Keep in mind that this data have to be
117 cached for any reasonable performance. On the other hand, data can be
118 structured usefully, for example trees are structured in useful way for
119 direct output to JSON.
120
121 If tree has C<class> key, it can be set to C<error> so that we can mark
122 errors in data using same CSS class in views. This might be useful convention.
123
124 I prefer to keep this file documented up to level that make it's usage from Jifty and
125 C<t/50-strix.t> makes sense, but not more than that.
126
127 =head1 HTML
128
129 We don't generate HTML using templates. In fact, all HTML is encoded in perl
130 code using L<Template::Declare>. This allows easy generation of valid HTML,
131 high-level templates which are perl code and easy skinning using CSS.
132
133 C<share/web/static/css/app.css> is used to store application specific CSS.
134 It should probably be split into several files (Jifty will concatenate them
135 for us anyway) for easier maintenance, probably by same logic as view names
136 to skip additional step of mapping when human are watching into code.
137
138 In long run, this should allow us to refactor templates at code level and
139 create different re-usable widgets which brings us to following topic...
140
141 =head1 AJAX
142
143 Jifty's way of AJAX are L<Jifty::Manual::PageRegions>.
144
145 =head2 Strix navigation
146
147 L<http://a3c.skole.hr/strix/navigation>
148
149 For now, we have implementation of two-level select which is in sync with
150 instance clipboard (implemented by L<A3C::Model::StrixInstanceSelection> and
151 L<A3C::View::Strix> and L<A3C::Action::StrixSelectSite>. This is
152 good candidate to refactor into reusable widget on it's own.
153
154 =head1 BUGS
155
156 Many probably, documented in C<TODO> which is also useful for quick overview
157 what changed between versions if svn commit log is too detailed although
158 first line of commit message might be good summary of each individual
159 change.

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