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Contents of /lib/A3C.pod

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Revision 208 - (show annotations)
Thu Jun 19 21:24:26 2008 UTC (11 years, 11 months ago) by dpavlin
File size: 6226 byte(s)
another round of re-factoring

- re-organize LDAP-related pages under /ldap with new view A3C::View::LDAP
- move record multi-value support into A3C::Record
- document multi-value solution which started it all
1 =head1 NAME
3 A3C = AAAC; AAA from "Authentication, Authorization and Accounting" and C from "CARNet".
7 This page describes general idea about A3C application and current status of implementation.
9 Oppinions should be attributed to Dobrica Pavlinusic, and not other developers :-)
10 It's surposed 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.
15 =head1 Models
17 Models in Jifty are at perl level objects (with validation and
18 canonicalization) and tables in database.
20 For a start, we implement some magic documented in L<A3C::Record> on records
21 (rows in database).
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.
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 compex C<GROUP BY> and C<JOIN> queries which are hard
31 to express using L<Jifty::DBI>.
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.
36 =head1 LDAP
38 Implement LDAP entry and edit interface (insteresting problem since most
39 entries can have multiple values which doesn't map nicely to relational
40 schema).
42 =head2 Multiple values
44 When creating records with ARRAY values C<A3C::Record/create>
45 joins values with magic marker between them to make rest of Jifty happy.
47 Plan is to use full-text search engine to search over data anyway, so this
48 is not serious limitation. If needed, something like bitmap indexes could be
49 used at database level to expose thouse values for filtering. For joins we
50 would probably need separate materialized many-many tables which could be
51 created more-or-less automatically in L<A3C::Record>.
53 This can in turn be broken down into following tasks:
55 =head2 Import data from existing LDAP server
57 C<bin/import-ldap.pl> has embedded documentation and uses <A3C::LDAP>
59 L<http://a3c.skole.hr/ldap/> is user interface to L<A3C::View::LDAP> and
60 L<A3C::Action::SyncOrganization>
62 =head2 Query existing LDAP server
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.
70 =head2 Create new entries and edit existing ones
72 We are in the middle of migaration 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>
76 Most views I guess, will be implemented by subclassing L<Jifty::View::Declare::CRUD>.
77 Right now L<A3C::View::Organization> is such implementation.
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>.
83 =head2 Virtual LDAP server to publish data
85 This part is in planning stage, and it will probably be based on L<Net::LDAP::Server>.
87 =head1 Existing LDAP schema
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.
92 Some entries in LDAP schema have fixed list of attributed, and L<A3C::AAIEduHr>
93 implements fetcher (with cache) for that data.
95 =head1 Legacy portal integration
97 =head2 Parse PHP config files
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 agregates all instance data. Parser is
102 implemented by L<A3C::PHP>
104 =head2 Connect to remote database
106 Implemented in two different ways:
108 =head3 Direct SQL execution
110 L<A3C::Action::StrixSQL> and interface as L<A3C::View::Strix/sql>.
112 =head3 Fetching data hashes
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 resonable 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.
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.
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 sanse, but not more than that.
127 =head1 HTML
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.
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.
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...
141 =head1 AJAX
143 Jifty's way of AJAX are L<Jifty::Manual::PageRegions>.
145 =head2 Strix navigation
147 L<http://a3c.skole.hr/strix/navigation>
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.
154 =head1 BUGS
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 allthough
158 first line of commit message might be good summary of each individual
159 change.

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