[[Image(http://www.eobjects.dk/resources/IconMetaModel.png, nolink, right)]]
= !MetaModel =

About | [MetaModelDevelopersGuide Developers guide] | [MetaModelProgrammingWebcast Webcast demo] | [MetaModelCompliancy Database compliancy] | [MetaModelLicense License] | [http://code.google.com/p/metamodel/downloads/list Download]

A common domain model, query-engine and optimizer for different kinds of datastores.

The eobjects.org !MetaModel is a project created for maximum reuse of a SQL 99 compliant domain model of the database domain. The MetaModel is a model that contains classes that represent the '''structure''' of a database (schemas, tables, column, relationships) and '''interaction''' with the database (queries). In short a model for modelling (hence the word "metamodel") data in databases and other datastores.

!MetaModel is being used in a lot of projects, including the eobjects.org projects DataCleaner, DataTransformer and TableAgent. Additionally the QueryParser project is aimed at creating a String-based parser to populate the query-part of MetaModel by parsing incoming SQL queries.

{{{
#!html
<br/>
<div style="float:right; background-color: #f4f4f4; border: 1px solid #aaa; padding: 4px; width: 236px; margin-left: 10px;">
<big><b style="color: #007b00;">MetaModel <big>1.2</big> is out!</b></big><br/>
We're proud to present a new major release of <a href="/trac/wiki/MetaModel">MetaModel</a>! <a href="http://code.google.com/p/metamodel/downloads/list">Go download</a> this innovative new datastore manager, optimizer and metadata component!
<br/><br/>
How does it work?<br/>
Watch the <a href="/trac/wiki/MetaModelProgrammingWebcast">webcast</a>!
</div>
}}}

== Goals ==
The goal of MetaModel is to provide an API for:
 * Traversing and building the structure of datastores.
 * Executing datastore-neutral queries in a SQL-like manner.
 * Provide datastores that do not support queries with a [QueryPostProcessor query engine].
 * Implement this system for JDBC databases, Comma-separated files, XML files, Excel spreadsheets, MS Access (.mdb), dBase (.dbf) and !OpenOffice (.odb) database-files.
 * Allow [CompositeDataContext querying across datastores] in a way that is similar to querying a single datastore. This involves transparent client-side joining, filtering, grouping etc.
 * [QuerySplitter Split single queries into multiple ones] that yield the same collective result, enabling powerful performance optimization and grid execution for heavy work loads.

We are designing this API to be:
 * Comprehensive - !MetaModel should contain all the functionality that is required to model the datastore domain.
 * Easy to use - We focus on simple design and fluent interfaces to make the most commonly used functionality easy and fun to use.
 * Consistent - With MetaModel you will not experience all the ambiguities that exist in other frameworks like JDBC. Instead of diversity and hacks we focus on standardization and a common datastore infrastructure - all nescesary hacks have been hidden from you, the user.
 * Extensible - We provide extension-points to make it possible to use MetaModel for your own legacy systems, for example to query datastores that may not be supported.
 * Light-weight - Deliberate use of POJOs make it easy to understand what is going on inside !MetaModel.

== Using with Maven ==
Add this dependency entry to your Maven POM to include MetaModel in your project:
{{{
<dependency>
 <groupId>dk.eobjects.metamodel</groupId>
 <artifactId>MetaModel-full</artifactId>
 <version>1.2</version>
</dependency>
}}}

== Contributing ==
There are several ways you can contribute to MetaModel...

 * Post your ideas to the [http://groups.google.com/group/metamodel mailing list].
 * Add [/trac/newticket?component=MetaModel new tickets] for future development.
 * Check out the code and post patches, see BuildingMetaModel.
 * [DonateToEobjects Donating money to eobjects].