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| In an OSGi environment, there are two kinds of dependencies between various bundles: | |
| <span class="emphasis"><em>type</em></span> dependency and <span class="emphasis"><em>service</em></span> dependency. | |
| </p><div class="itemizedlist"><ul type="disc"><li><p> | |
| <span class="bold"><strong>Type dependency</strong></span>: A bundle may depend on a | |
| type exported by another bundle thus creating a type dependency. Type | |
| dependencies are managed through <code class="literal">Import-Package</code> and | |
| <code class="literal">Export-Package</code> directives in the OSGi manifest. This | |
| kind of dependency is similar to a JAR file using types in other JAR files | |
| from the classpath. However, as we’ve seen earlier, there are | |
| significant differences. | |
| </p></li><li><p> | |
| <span class="bold"><strong>Service dependency</strong></span>: A bundle may also | |
| publish services (preferably using Spring-DM), and other bundles may consume | |
| those services. If two bundles depend on the same service, both will be | |
| communicating effectively to the same object. More specifically, any state | |
| for that service will be shared between all the clients of that service. | |
| This kind of arrangement is similar to the commonly seen client-server | |
| interaction through mechanisms such as RMI or Web Services. | |
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