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Tangram(3pm)

NAME

   Tangram - Store pure objects in standard relational databases

SYNOPSIS

   See Tangram::Tour

DESCRIPTION

   Tangram is an object-relational mapper.  It is orthogonal, meaning that
   it does not require anything of the objects stored in it (other than
   the common convention that base objects be based upon HASHes;
   individual columns can be anything).

   It consists of a schema language that can describe or be built around
   an object structure, or so as to closely match an existing SQL schema
   (with some limitations).  This schema language is rich enough to
   express such common RDBMS features as links, foreign keys, and link
   tables.

   It also consists of a relational database storage engine, which based
   on the schema structure, will make Perl structures persist in a
   relational (SQL compliant) database.  References to other objects (or
   collections, as represented with foreign keys and link tables) may be
   loaded using on demand references that `lazily' load data when it is
   needed.

   As of Tangram 2.08, the schema need not describe every single object
   property, so that you can map only the columns you intend to query.
   The rest of the object is then stored in a column via a serialiser,
   like Data::Dumper, YAML or Storable.  These structures themselves may
   contain arbitrary references to other objects in storage.

   Tangram has soundly engineered transaction support, without sacrificing
   excellent data caching abilities.  The general optimisation strategy of
   the code makes it most suited for OLTP (aka application servers) and
   other situations where it is better to select and update whole rows
   than to worry about which columns to retrieve/update or not
   retrieve/update.

   Once your object are persistent, you can build query expressions to
   find them in terms of the schema language that you used to put them in.
   Therefore, the schema data structure does not describe a data
   structure, it describes a data access pattern.

   If you are not picky about which accessor module to use, preferring to
   specify the schema once only, then you can use the separately
   distributed Class::Tangram::Generator to make a set of classes from a
   Tangram schema structure.

   If you are looking for a tool that implements SQL abstraction only, you
   have probably missed the point (of this module, anyway), and a well-
   supported module like Class::DBI, or an interactive SQL modeller like
   Alzabo will likely suit your needs better.

   Tangram is beginning to include preliminary support for aggregation
   functions, and currently supports grouping, summing and counting.
   Joins must currently be in terms of integer primary key columns, to
   extend past this would require extra mapping types to be developed.
   Basic support for alternative join types is present, but in its
   infancy.

   Tangram currently contains no support for database-side updates (ie,
   "UPDATE foo SET bar = 'baz' where frop = 'blarg'"), but support is
   planned.

   There is no support for creating views based on existing classes to
   make new derived classes; you have to use your database SQL and create
   corresponding Tangram classes manually to do that.

   Tangram has a web site at <http://tangram.utsl.gen.nz/>, currently
   sponsored by MarketView (New Zealand) Ltd.

DOCUMENTATION INDEX

   Tangram::Tour
       The original "Guided Tour" of the features of Tangram, by Jean-
       Louis Leroy.

   Tangram::Intro
       The humble beginnings of a new guided tour, based on the next-
       generation features found in Tangram 2.08.

   Tangram::Springfield
       The classes and schema used in the Guided Tour(s).

   Tangram::Storage
       The main database handle class.  Includes details on query syntax.

   Tangram::Cursor
       Return an iterator that retrieves persistent objects in a result
       set one by one.

   Tangram::Schema
       The Tangram schema structure - representing your data model so that
       Tangram can map it.

   Tangram::Relational::Mappings
       An informative text on exactly how Object Relational Mapping is
       accomplished by the Tangram::Relational back-end, what the
       different styles of mapping are, and how each is selected.

   Tangram::Type
       What Tangram types are available.  This page is an index of other
       manual pages that express the data and relationship types available
       in Tangram.

   Tangram::Type::Extending
       How to write your own custom types for Tangram.

   Tangram::Dialect
       Database-specific extensions to Tangram, such as Tangram::mysql and
       Tangram::Sybase.  These extensions only add functionality, and are
       not required for core operation of Tangram.

COMPATIBILITY

   Tangram has been known to run in the following environments, however,
   Tangram uses standard SQL and should be usable with any SQL-83
   compliant database.  Most of the requirements are simply avoiding the
   worst bugs.

   Note that some functions (e.g. transactions and subselects) may not be
   available in some environments. This is reported during the test suite.

   *   Perl 5.005_03+, 5.6.1+, 5.8.1+ (5.8.0 had a nasty bug and doesn't
       work with Tangram)

   *   Set::Object 1.04 (though the latest version is highly recommended)

   *   DBI 1.14

   *   DBD::mysql 2.0402

   *   DBD::Oracle 1.06

   *   DBD::Sybase 0.21

   *   DBD::SQLite 1.07

   *   DBD::Pg 0.93

LICENSE & WARRANTY

   You may use Tangram, free of charge, under the terms of the GPL.  This
   notice applies to the entire distribution and all of its parts.

   You can obtain a commercial license for old (2.04 and earlier) versions
   of Tangram from Sound Object Logic, see
   http://www.soundobjectlogic.com/tangram/licenses.html.

   TANGRAM COMES WITHOUT ANY WARRANTY OF ANY KIND.  IT DOES NOT EVEN COME
   WITH ANY KIND OF VAGUE IMPLICATION THAT IT DOES ANYTHING MORE THAN GIVE
   YOUR COMPUTER HINTS ABOUT HOW TO TRY STIRRING ITS ELECTRONS.  THE
   AUTHORS ARE NOT RESPONSIBLE FOR THE RESULTANT ELECTRON CONFIGURATION IN
   ANY WAY INCLUDING TRANSMUTATIONS OF ELECTRONS INTO OTHER FIELDS SUCH AS
   MAGNETIC MEDIA OR PUNCH CARDS.

SUPPORT

   Please send bug reports directly to the Tangram 2 maintainer's mailing
   list <t2-users@lists.utsl.gen.nz>, and please CC:
   <bug-Tangram@rt.cpan.org> so your fault can be tracked accurately.

   Whenever possible, include a short yet complete script demonstrating
   the problem.  (read: if you want it fixed quicker, demonstrate it)

   Questions of general interest should should be posted to the mailing
   list, but not sent to rt.cpan.org.

AUTHORS

   All the code and documentation for versions 2.04 and earlier, as well
   as some changes in the 2.05 release, were written by Jean-Louis Leroy
   (jll@soundobjectlogic.com) and Sound Object Logic.

   Sam Vilain <sam@vilain.net> is the author of the derived work that is
   Tangram 2.05 and later.

   Andres Kievsky <ank@cpan.org> has contributed to the Tangram code
   starting with Tangram 2.08.

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