COMPONENT ARCHITECTURE  EXAMPLE

DEFINITIONS:

 Services: Collections of tasks performed to support multiple applications. Logical basis for reuse.
 Components: Software units that provide services or application logic. Physical basis for reuse.
 Framework: Container that provides interface to components, process templates and some services. 
 Interfaces: Defined protocols for accessing services.
 Architecture:  A structure that combines frameworks, services, components, and interfaces.
 Business Objects: Software unit that combines business data and business logic 
 Application:  Software written to satisfy specific business process requirements

RELATIONSHIPS:

   Services can be provided by one or more components working together.
   Components can also provide access to legacy services.
   Components can be reused in one or more  frameworks.
   Frameworks can be extended by layering.
   Frameworks can be components in larger frameworks
   Interfaces can be implemented by one or more components.
   Components can implement one or more interfaces.
   Components can contain more than one business object.
   Components can be extended by composition
   Business objects can be shared by many different components.
   Business objects can be extended by inheritance
   Applications should use services provided by frameworks and components.
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EXAMPLE: An example of the architecture-based approach is the use of 
reusable services, components, frameworks, and business objects in Web
applications. In the simplified example below this is illustrated by using 
a generic business process (Internet boat purchase) to derive potentially
reusable elements.

SERVICES: 

    These business services are reusable across multiple applications. There
  will also be infrastructure services required such as security and 
  transactions. 
 


 Configure boat
      Service Interface Protocol – 
                                      Retrieve a boat template
                                      Enter parameters
                                      Submit request for evaluation 
                                      Receive approved configuration or errors
                                      Correct errors.

 Display 
     Service Interface Protocol – 
                                     Submit a correct configuration
                                     Receive a display of the boat 

 Price a boat
     Service Interface Protocol – 
                                    Submit a correct configuration
                                    Receive a price quotation
                                    Negotiate price based on trade-offs

 Locate a boat
     Service Interface Protocol – 
                                    Submit a boat description
                                    Receive a boat ID and Dealer ID or location
                                  
 Locate a dealer
    Service Interface Protocol – 
                                   Submit a  dealer ID
                                   Receive a dealer location

 Contact a dealer
    Service Interface Protocol – 
                                  Submit a dealer ID
                                  Receive dealer contact information
                                 Contact dealer
 Obtain credit
    Service Interface Protocol – 
                                  Submit financial information
                                  Obtain credit approval

 Order a boat
    Service Interface Protocol – 
                                   Submit an order
                                   Receive confirmation
                                   
                           

COMPONENTS:

    To provide each of the services above, it will be necessary to build
groups of components. Some examples of the groups are below. There may
be multiple components performing similar functions based on diversity 
in areas such as boat models or geographical region.

 Configure boat components:
      Boat template manager
      Boat configuration evaluator
     

 Display boat components: 
    Configuration to display mapper
    Display file processor(e.g. decompression, streaming etc.)
    Display user interface

 Price a boat components:  
    Configuration to price mapper

 Locate a boat components: 
     Boat ID to location mapper

 Locate a dealer components: 
    Dealer ID to location mapper

 Contact a dealer components:
    Dealer ID to contact information mapper
    Dealer contact tool

 Obtain credit components:
    Financial data evaluator

 Order a boat components:
   Order processor

BUSINESS OBJECTS:
     
 Boat template
 Boat configuration(= filled-in template)
 Boat display
 Boat ID
 Boat location
 Dealer ID
 Dealer Locations
 Boat order

FRAMEWORK: 

   The  choices for frameworks could be an application 
server that can support Java and/or ActiveX interfaces. Some
possibilities include Netscape’s Application Server, Microsoft MTS,
IBM’s Transaction Server,NetDynamics, Bluestone’s Sapphire Web, and 
WebLogic’s Tengah. These products do not currently support process 
templates but this is a natural next step.

INTERFACES: 

   The choices for the basic components include include CORBA objects, COM
components or Java Beans. The service interface protocols can be created in
a scripting language such as Visual Basic or JavaScript. 

ARCHITECTURE:

   The choice of possible frameworks and component architectures should be 
an enterprise decision. Multiple applications can be created by different 
combinations and extensions of the components within the framework structure.