CORBA Environments 47
Figure 6. Component Broker Building Blocks
Leaving aside the somewhat amorphous, elliptical “blob” on the left for a
moment, let us go over the figure from left to right and from top to bottom.
7.2.2 Component Broker Dimensions
The three dimensions of Component Broker are:
System management Runtime
Component Broker connects to most of today’s popular client environments.
It supports clients written as Java applets and applications, clients developed
for Microsofts ActiveX platform, and clients written in VisualAge for C++.
While you certainly can continue to run fat-client topologies, Component
Broker is ideally suited for the thinner client variety. Component Broker does
not restrict you in any way from using your favorite GUI frameworks or tools.
48 Using VisualAge for Java Enterprise Version 2 to Develop CORBA and EJB Applications
You code the user interface and any local business logic as usual. In addition,
the developers of your Component Broker server code will provide you with
the constructs needed to hook up to your server. What you get depends on
your client platform. In any case, the appropriate source code usage bindings
are available for all of the above environments. Java code can be
downloaded or cached locally on the client, as usual. In the other
environments, you have to install the necessary dynamic link libraries (DLLs)
to build and run your application. All clients connect to the application server
through a CORBA-compliant ORB using IIOP. However, the core of
Component Broker lies in its middle-tier application server. The server allows
you to separate the traditionally extremely “volatile” client software
environment from the code that implements your business logic. It also
isolates that business logic from back-end technology specifics, such as
databases or transaction monitors. Thus it provides you more opportunity to
concentrate on the demands of your business, leaving the idiosyncracies of
the other tiers to the specialists in those areas. The main components housed
within the middle-tier application server are:
Application Adaptor and Managed Object Frameworks
These components provide the core infrastructure and scaffolding for your
business logic to enable it to run in a mission-critical environment. They
take care of such aspects as transactional behavior, connecting to back-
end datastores and transaction monitors for persistence or legacy reuse,
and interfacing to OMG object services. Application Adaptor and Managed
Object frameworks “administer” what is called a
Managed Object
. Of that assembly, what is “visible” to a developer are the
following objects:
Business objects
These contain your actual business domain code, that is, your
business logic.
Data Objects
These isolate the business objects from the specifics of back-end
databases and transaction monitors. The data objects themselves use
the services of other, framework-provided objects to implement the
connection to back-end data stores. They can make use of extensive
caching services to provide the kind of performance you would expect
in today’ s online environments.
Managed objects
These “wrap” business and data objects. The framework interfaces
primarily with managed objects. When business logic operations are
invoked on a managed object, the implementation is delegated to your
business object. Component Broker-required methods are either
implemented by the managed object itself or delegated to other parts of

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