Java Reference
In-Depth Information
The Karaf web console
If you prefer to use a GUI console, you can install the optional web console into Karaf
using the command features:install webconsole . Because of OSGi's dyna-
mism, as soon as the console feature is installed, the web console will be available.
If you miss the command line, the web console even embeds a version of the shell.
Sadly, the one thing absent from the web console is the shell's Blueprint status list.
Karaf is a nice integration framework, with many handy extensions to what you get if
you run a plain OSG i framework like Felix or Equinox. We like the console and the
integrated Blueprint support. But Karaf isn't an application server; even if you add in
lots of Karaf features, it won't do all the things an application server does.
Apache Geronimo
If Karaf is too low-level for you, you'll find many of the same characteristics in Karaf's
bigger cousin, the Apache Geronimo application server. From version 3.0 onwards,
Apache Geronimo supports the enterprise OSG i programming model. Geronimo pro-
vides a feature-complete and well-integrated enterprise OSG i runtime, based on
Apache Aries. As with Karaf, the version of Aries embedded in Geronimo will usually
lag slightly behind the leading edge release of Aries itself.
Geronimo itself is built on top of Karaf, so it retains many of Karaf's excellent fea-
tures, such as the Blueprint-aware console. But unlike Karaf, Geronimo is a full-
fledged Java EE -certified application server. This means many features that have to be
manually installed or hand-cranked in Karaf work out of the box in Geronimo. (The
corollary of this is that Karaf is a lot faster than Geronimo—or almost anything else—
to start!) Geronimo ships with a built-in Derby database, EJB container, JMS container,
and transaction manager. If you plan to combine Java EE and OSG i components, you'll
be grateful for this extra function. Even if you're doing a strictly OSG i application, you
may find Geronimo's management and debugging facilities handy. Geronimo's OSG i
application management is more well-integrated and sophisticated than Karaf's. For
example, Geronimo's console displays the web context root of installed WAB s (see fig-
ure 13.4).
The Geronimo web console also provides more general management of installed
OSG i bundles. Graphical views of a bundle's wired bundles, imported and exported
services, and manifest are provided by the console (see figure 13.5).
Geronimo is one of the most straightforward ways to use Apache Aries; Geron-
imo contains most of the Apache Aries components you've been using through this
topic, but it wraps them in a proper application server environment, with administra-
tion, databases, datasources, JPA entity enhancement, security, and other application-
server goodies.
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