OSGI class space

osgi
1:service作用是提供了bundles之间的联系和交互
2：Fragment自己没有独立的classloader，它使用宿主bundle的classloader。
3：Each bundle has a single classloader.
   The class loader can load classes and resources from:
• Boot class path – The boot class path contains the java.* packages and its
implementation packages.
• Framework class path – The Framework usually has a separate class loader
for the Framework implementation classes as well as key service
interface classes.
• Bundle Space – The bundle space consists of the JAR file that is associated
with the bundle, plus any additional JAR that are closely tied to the
bundle, like fragments, see Fragment Bundles on page 69.
A class space is then all classes reachable from a given bundle’s class loader 类空间是指一个指定的bundle的classloader所有能够访问到的类。