Hi all,
I've been playing around with Service Binder
(http://gravity.sourceforge.net/servicebinder/) for the past week or
so (thanks Richard and Humberto!). My team is strongly considering
OSGi as the base of a re-implementation of one of our enterprise
systems here, currently based on Spring
(http://www.springframework.org). Since we all know and love Spring,
I wanted to see if I could work it into OSGi somehow.
I've modified the latest ServiceBinder implementation to load its
service instances from a Spring BeanFactory, instead of trying to
dynamically instantiate the classes itself. I also got rid of the
standalone ServiceBinder XML file and integrated ServiceBinder
definitions directly into the Spring XML files. Now services might be
defined like this:
==========================================================
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "binder-beans.dtd">
<beans>
<bean id="hibernateServiceImpl" singleton="false"
class="test.orm.hibernate.impl.HibernateServiceImpl">
<instance>
<provides interface="test.orm.hibernate.HibernateService"/>
<osgiproperty name="version" value="1" type="string"/>
<desires
service="test.service.ServiceProvider"
filter="(version=*)"
cardinality="0..1"
policy="dynamic"
bind-method="setService"
unbind-method="unsetService"
/>
</instance>
<property name="dataSource"><ref bean="hibernateDataSource"/></property>
<property name="properties">
<props>
<prop
key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
<prop key="hibernate.jdbc.batch_size">0</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
</property>
</bean>
<bean id="hibernateDataSource"
class="org.apache.commons.dbcp.BasicDataSource">
...
</bean>
</beans>
==========================================================
Bean XML definitions are specified with the "Bean-Definitions"
manifest entry; e.g.,
Bean-Definitions: beans/hibernate.xml, beans/someservice.xml
The old ServiceBinder XML file has been replaced with the <instance/>
element in the new <bean/> definition (some element names have been
changed). Any bean that contains an <instance/> element will be
handed to ServiceBinder.
Some issues currently:
* I would like to support wildcard lookup of bean files, but there
doesn't appear to be any way to get a list of resources from a bundle.
As of now, each xml file has to be explicitly specified.
* Each service bundle requires its own BeanFactory instance (not sure
about the overhead with this).
* Logging all goes to stdout.
I've made it available for download at:
http://www.rit.edu/~jrv4595/springservicebinder.zip
Since the Spring jar is included (twice- once in the source tree and
once in the compiled bundle), the archive is about 5mb.
Any questions/comments/suggestions are greatly appreciated. :)
-Jeremy
