Java Reference
In-Depth Information
Keeping the core platform small is important to
OSG
i because the core platform
must
be shared by all
OSG
i users, whether they're running an embedded system inside a car
radio or on an enterprise production server with hundreds of gigabytes of memory.
T
HE
E
NTERPRISE
E
XPERT
G
ROUP
The
EEG
is a comparatively new member of the
OSG
i Alliance, having only been set up
in 2008, but as with most new standardization efforts, a lot happened quickly. Many of
the technologies used in the examples in this topic are
OSG
i Enterprise Specification
standards, or are heavily based on them.
EEG
's focus is, as you would expect, enter-
prise-level technology. This means that
EEG
specifications typically focus on technolo-
gies that will be useful on hardware scales running from laptops to mainframes.
Primary requirements for
EEG
specifications are typically qualities of service, data
access, and remote communication. The Enterprise Expert Group also works toward
making
OSG
i a more suitable container for large-scale applications.
B.2
OSGi specifications
Although we tend to talk about
OSG
i, there are several different
OSG
i specifications.
Each one defines a range of services and technologies, although some chapters are
duplicated across the various noncore specifications.
We've been discussing core
OSG
i, but
OSG
i is a big platform. In addition to the
Core Specification, there are a number of other specifications, each defining a range
of extra services and technologies. It's important to know about the various
OSG
i spec-
ifications to understand why there are lots of
OSG
i-related open source projects, each
of which seems to provide a different set of features.
There are four
OSG
i specifications—the Core Specification, the Services Compen-
dium, the Enterprise Specification, and the Mobile Specification. The relationship
between the specifications is illustrated in figure B.1. The Compendium, Enterprise,
The OSGi Service Platform
Residential
Specification
New
in 4.3
Compendium Specification
Mobile
Specification
Enterprise Specification
Core Specification
Figure B.1
The OSGI service platform includes a number of specifications. The Core Specification is
the foundation on which the other specifications are built. The Compendium Specification defines a
range of extra services. The Enterprise and Mobile Specifications are subsets of the standards defined
in the Compendium Specification. Some elements of the Enterprise Specification were defined after the
most recent version of the Compendium Specification and will be rolled back into the next version.
