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Hibernate is an excellent Object Relational Mapper. Using just xml files, or annotations, we are able to describe the relationship between all of our tables and our domain (POJO) objects (like Patient.java, Concept.java, etc). Looking at the concept domain in the datamodel, we see that it consists of tables named concept, concept_answer, concept_set, concept_name. It would be very difficult to keep up with where to store each part of the concept object and the relations between them. Using Hibernate, we only need to concern ourselves with the Concept object, not the tables behind the object. The concept.hbm.xml mapping file does the hard work of knowing that the Concept object contains a collection of ConceptSet objects, a collection of ConceptName objects, etc. To add a new name to a concept:

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OpenMRS lives in a Git repository.  See the Code Repositories wiki page for more info.

Building OpenMRS

OpenMRS uses Maven to manage the libraries and build system.  See that wiki page for more info.

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OpenMRS has a modular architecture, meaning that "modules" (i.e., add-ons or extensions) can be added to the system to add new behavior or alter existing behavior. OpenMRS Add-ons index hosts publicly downloadable modules; these can be installed directly from within OpenMRS as well.  See the Module documentation for developers.  Modules are allowed to interact with OpenMRS on every level.  They can provide new entries into the Spring Application Context, new database tables, new web pages, and even modify current service layer methods.

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