This document outlines a 5-step process to modularize the OpenMRS application using OSGi bundles. The first step is to create a "mega bundle" that includes all dependencies. The next three steps involve extracting the core API, web, and webapp modules into separate OSGi bundles. The final step is to define an execution plan for the Virgo OSGi server to run the modularized application as individual bundles. When completed, the OpenMRS application will be split into interoperable modules running within an OSGi container.

1. by Filip Spiridonov

2. 
 Is a standard for modularity in Java
 Module’s metadata is in META-INF/MANIFEST.MF
OSGi
jar
META-INF/
MANIFEST.MF

3. 
OSGi container
openmrs.war
openmrs-api.jar
openmrs-web.jar
openmrs-
webapp.jar
dependency1.jar
dependencyN.jar
module1.jar
moduleN.jar
tomcat.jar
Project’s idea

4. 
 Place metadata config declarations to webapp.bnd
 Use maven-bundle-plugin to add manifest file to
openmrs.war
 Run this mega bundle inside an OSGi container
Step 1 – Mega bundle

5. 
OSGi container
openmrs-api.jar
dependency1.jar
dependencyN.jar
tomcat.jar
Step 2 – Api to OSGi

6. 
 Understand dependencies
 Create openmrs-api.jar with manifest
 Extract dependency libs to separate bundles
 Explicitly share spring services and validators
(META-INF/spring/*.xml)
Step 2 - algorithm

7. 
OSGi container
openmrs-api.jar
dependency1.jar
dependencyN.jar
tomcat.jar
openmrs-web.jar
Step 3 – Web to OSGi

8. 
 Create openmrs-web.jar with manifest
 Extract dependency libs to separate bundles
 Import shared spring services and validators
Step 3 - algorithm

9. 
OSGi container
openmrs-api.jar
dependency1.jar
dependencyN.jar
tomcat.jar
openmrs-web.jar
openmrs-
webapp.jar
Step 4 – webapp to OSGi

10. 
 Webapp depends only on api and web
 web.xml is modified to not load spring contexts
(Each bundle creates it’s own context and can share
some beans with others)
Step 4 – algorithm

11.  Creating execution plan for Virgo OSGi server
<plan …>
<artifact type="bundle" name="com.springsource.net.sf.cglib"/>
<artifact type="bundle" name="com.springsource.antlr"/>
<artifact type="bundle" name="com.springsource.com.thoughtworks.xstream"/>
<artifact type="bundle" name="com.springsource.org.apache.commons.beanutils"/>
<artifact type="bundle" name="com.springsource.org.dom4j"/>
<artifact type="bundle" name="com.springsource.org.xmlpull"/>
<artifact type="bundle" name="org.apache.commons.cli"/>
<artifact type="bundle" name="org.apache.commons.collections"/>
…
<artifact type="bundle" name="org.openmrs.api.openmrs-api"/>
<artifact type="bundle" name="org.openmrs.api.openmrs-web"/>
<artifact type="bundle" name="org.openmrs.api.openmrs-webapp"/>
…
</plan>
Step 5 – Virgo plan

12. 
Result

13. 
Running bundles

14. 
 Server github repo:
https://github.com/NameFILIP/openmrs-virgo-
server.git - (to run: “bin/startup.sh”)
 Source github repo:
https://github.com/NameFILIP/openmrs-
core/tree/OSGi
Thank you