Managing applications - OSGi in Action - page 321

manipulate a running framework. One of the more critical aspects of managing the
framework is determining which bundles should be deployed to it. Various strategies
are possible to manage complex sets of interdependent bundles. The two most promi-
nent at the moment are the OSG i Bundle Repository ( OBR ) and Deployment Admin.
OBR and Deployment Admin address bundle deployment from different angles,
but both can help when it comes to developing a management agent. The difference
in focus between the two can be summarized as follows:

OBR focuses on remote discovery and deployment of individual bundles and
their dependencies.

■

Deployment Admin focuses on the deployment of sets of bundles and associ-
ated resources.

■

In the following sections, we'll explore these two technologies in more detail and
show you how to use them to provision or deploy your applications and bundles.

Alternative technologies
A number of other technologies attempt to address deployment and provisioning for
OSGi, including Apache Ace, Paremus Nimble, and Equinox p2:
■ Ace is a software distribution framework based on Deployment Admin. It focuses
on centrally managing target systems, and distributing software components,
configuration data, and other artifacts to them. The target systems are usually
OSGi-based, but they don't have to be.
■ Nimble is based on open source work from the Newton project and focuses on
building an extensible resolver architecture that can deal with other types of
dependencies outside of the OSGi modularity layer, such as service-level depen-
dencies. For example, if a bundle containing servlets is deployed and activated,
a servlet container should be deployed and activated alongside it.
■ p2 is a subproject of the Eclipse Equinox framework. p2 focuses on extending
the types of deployable artifacts to encompass things outside of an OSGi envi-
ronment, including Unix RPM packages or Windows services, for example.
We won't discuss the details of any of these in the remainder of this topic. If you're
interested in them, they're just a Google search away.

10.1.2 OSGi Bundle Repository

The OSG i Bundle Repository ( OBR ) is officially not an OSG i standard specification;
rather, it's a proposal for a specification, internally referred to as RFC 112 in the OSG i
Alliance. Because OBR is only an RFC , its details may change in the future, but it's still
a useful tool as it is.
OBR started life as the Oscar Bundle Repository, which was associated with the
Oscar OSG i framework (which ultimately became the Apache Felix framework). OBR
is intended to address two aspects of bundle deployment: