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Overview
of CORBA Services
Event
Service
• The
Event Service provides basic capabilities that can be configured together in a
very flexible and powerful manner. Asynchronous events (decoupled event
suppliers and consumers), event "fan-in," notification
"fan-out," and (through appropriate event channel implementations)
reliable event delivery are supported.
• The
Event Service design is scalable and is suitable for distributed environments.
There is no requirement for
a centralized server or dependency on any global service.
• The
Event Service interfaces allow implementations that provide different qualities
of service to satisfy different application requirements. In addition, the event
service does not impose higher level policies (e.g., specific event types)
allowing great flexibility on how it is used in a given application environment.
• Both
push and pull event delivery models are supported: that is, consumers can either
request events or be notified of events, whichever is needed to satisfy
application requirements. There can be multiple consumers and multiple suppliers
events.
• Suppliers
can generate events without knowing the identities of the consumers.
Conversely, consumers can
receive events without knowing the identities of the suppliers.
• The
event channel interface can be subtyped to support extended capabilities. The
event consumer-supplier interfaces are symmetric, allowing the chaining of event
channels (for example, to support various event filtering models). Event
channels can be chained by third-parties.
• Typed
event channels extend basic event channels to support typed interaction.
• Because
event suppliers, consumers and channels are objects, advantage can be taken of
performance optimizations provided by ORB implementations for local and remote
objects. No extension is required to CORBA.
Object
Collections Service
Collections are groups of
objects which, as a group, support some operations and exhibit specific
behaviors that are related to the nature of the collection rather than to the
type of object they contain. Examples of collections are sets, queues, stacks,
lists, binary, and trees. The purpose of the Collection Object Service is to
provide a uniform way to create and manipulate the most common collections
generically.
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