CORBA%20Component

1
CORBA Component

• Component model
• Container programming model
• Component implementation framework
• Component packaging and deployment

2
The Component Model

• Component Implementation Definition Language
  (CIDL)
• Superset of PSDL
• Code generation
• Component type
• Ports
• Facets specifies a components functionality as
  a set of interfaces rather than as a single
  interface with simple IDL interface definition
• Configuration ports specifies how a component
  can be connected to other components that
  communicate either through invocation or event
  notification
• Basic component
• Regular CORBA object
• Extended component
• Component homes generalizations of the factory
  design pattern for creating, locating component
  instances
• Component instances are accessed through regular
  CORBA object references

3
Facets

• Facets specifies a components functionality as
  a set of interfaces rather than as a single
  interface with simple IDL interface definition
• include ltCosEventChannelAmin.idlgt
• Module ComponentEventChannel
• interface ManagedObject
• // management operations
• component EventChannelComp supports
  ManagedObject
• // facets
• provides ProxyPushConsumer proxy_push_consumer
• provides ProxyPushSupplier proxy_push_supplier
• provides ProxyPullConsumer proxy_pull_consumer
• provides ProxyPullSupplier proxy_pull_supplier

4
Facets

• Component equivalent interface
• interface EventChannelCompComponentsCCMObject,
  ManagedObject
• ProxyPUshConsumer proxy_push_consumer()
• ProxyPushSupplier proxy_push_supplier()
• ProxyPullConsumer proxy_pull_consumer()
• ProxyPullSupplier proxy_pull_supplier()

5
Facets

Equivalent interface
proxy_push_consumer
proxy_pull_consumer
Facets
proxy_push_supplier
proxy_pull_supplier
6
Configuration and Composition Ports

• Attributes and inheritance
• Attributes are declared in a component definition
  
• Attributes should be used only for configuration
  purposes
• Inheritance between component types is restricted
  to single inheritance
• Receptacles
• A named connection point that accepts interfaces
  and connects these to the component for future
  use.
• Event sources and sinks
• Special facets and receptacles

7
Component Ports
Equivalent interface

component
Receptacles
Facets
Event sources
Event sinks
Attributes
8
Component Homes

• Primary entry point for clients into the world of
  component
• Type managers for component types
• Provide set of operations
• Default operation no-argument factory operation
  for components of the type they manage
• More factory operations
• Find operations to retrieve individual,
  preexisting component instances

9
Component Container

• Container runtime environment for component
  instances
• Functionality of the containers
• Create and manage component instances
• Provide a simplified standard API to the CORBA
  services

10
Component Container

Home
Component
Client
External
Callbacks
Internal
POA
ORB
Transactions
Security
Persistence
Notification
11
Component Categories

• Component categories is defined in CIDL, not in
  IDL
• Not properties of component types
• Categories
• Service
• Lifetime of service component is restricted to
  the lifetime of a single operation
• Cannot be associated with persistent state
• Transient state is not visible to clients
• Require no client interaction
• Home for service components provides only factory
  operations, not finder operations
• Computation that only return results can be
  thought of as service component

12
Component Categories

• Categories
• Session
• Has only transient lifetime and no persistent
  state
• Have a lifetime of client interaction
• Online shopping
• Process
• Has persistent reference and persistent state
• Model business processes
• Well-defined lifetime
• Component home provide factory operations, no
  finder operations
• Entity
• Modeling persistent entities
• Expose their persistent identity, i.e., a primary
  key
• Home provide a finder operation

13
Component Packaging and Deployment

• Deployment
• Selecting target containers for component
  implementations
• Installing component homes and instances from
  packages
• Configuring component properties
• Connecting components via interface and event
  ports
• Descriptors
• Software package descriptors
• Component descriptors
• Component assembly descriptors
• Property file descriptors