74. Closeable Service¶

A plugin can publish a net.solarnetwork.service.CloseableService and SolarNode will invoke the closeService() method on it when that service is destroyed. This can be useful in some situations, to make sure resources are freed when a service is no longer needed.

Blueprint does provide the destroy-method stop hook that can be used in many situations, however Blueprint does not allow this in all cases. For example a <bean> nested within a <service> element does not allow a destroy-method:

<service interface="com.example.MyService">
    <!-- destroy-method not allowed here: -->
    <bean class="com.example.MyComponent"/>
</service>

If MyComponent also implemented CloseableService then we can achieve the desired stop hook like this:

<service>
    <interfaces>
        <value>com.example.MyService</value>
        <value>net.solarnetwork.service.CloseableService</value>
    </interfaces>
    <bean class="com.example.MyComponent"/>
</service>

Note

Note that the above example CloseableService is not strictly needed, as the same effect could be acheived by un-nesting the <bean> from the <service> element, like this:

<bean id="myComponent" class="com.example.MyComponent" destroy-method="close"/>
<service ref="myComponent" interface="com.example.MyService"/>

There are situations where un-nesting is not possible, which is where CloseableService can be helpful.