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MetaModel

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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.


MetaModel 1.2 is out!
We're proud to present a new major release of MetaModel! Go download this innovative new datastore manager, optimizer and metadata component!

How does it work?
Watch the webcast!

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 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 querying across datastores in a way that is similar to querying a single datastore. This involves transparent client-side joining, filtering, grouping etc.
  • 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...