Advanced component frameworks - OSGi in Action - page 411

To r u n t h i s c o m b i n e d p a i n t p r o g r a m , g o t o t h e c h a p t e r 1 2 / p a i n t - e x a m p l e - m i x e d
directory of the topic's companion code. Type ant to build the example and java
-jar launcher.jar bundles to execute it. All the components from the different
frameworks integrate nicely into a single application.

12.4 Summary

Component frameworks can simplify the task of creating OSG i-based applications and
add useful capabilities, including lazy initialization, complex service-dependency man-
agement, and configuration externalization. Often, you'll end up having to do a lot of
this work yourself, so using a component framework can free you from the drudgery.
The following list summarizes the component frameworks we've investigated in
the past two chapters:

Declarative Services is an OSG i specification and is the simplest framework,
offering management of service dependencies and component configuration.

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Blueprint is also an OSG i specification and provides features similar to Declara-
tive Services, but with a richer configuration model. It's familiar to developers
who come from a Spring background.

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i POJO is an open source solution that uses byte-code instrumentation of compo-
nents to offer a well-rounded and sophisticated framework for building
dynamic, service-based applications.

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With any of these component frameworks, you can build rich, dynamic, OSG i-
based applications, with the added bonus that they can all integrate and collab-
orate via the OSG i service registry.

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Now we'll switch focus from dealing with the internal structure of your applications to
external concerns. Until now, we've assumed that applications are a set of bundles
running inside an OSG i framework, but sometimes they're more complicated. For
example, you may need to be in control of how your application is launched, or you
may not be able to package an entire application as bundles. What do you do then? In
the next chapter, we'll look at how to launch and/or embed an OSG i framework.