Consideration when choose arch

• Structural pattern
• Computational model
• Essential invariant of the style
• Common specialization

Pipe and Filter

• Def
  • Each component has input and outputs
  • Component reads stream of data on its inputs and produce stream of data on its data output, and delivering a complete instance

    

• Benefits
  • Easy understand the overall input/output behavior
  • Reusability
  • Enhancements & Maintenance
    • Easy to add and replace new filter or alternations
• Disadvantages
  • Designer should consider transformation of input data to output data
  • Filters are inherently dependant
  • Not good at handling interactive applications

Data Abstraction and Object Oriented Organization

• ADT
• Def
  • Primitive operations are encapsulated in an object or ADT
  • ADT is responsible for preserving the integrity of resources
  • Representation is hidden from other objects
• Benefit
  • Change implementation without affection those clients
  • Designer can decompose the problem into collections.
• Disadvantages
  • Must know identity of the other objects.
    • In the contrast, filters (pipe and filter) don't need to know what other filters are in the systems.

    

Event based, Implicit invocation

• Def
  • Implicit Invocation is that instead of invoking procedure call directly, a component can announce one or more events, other component can register an interest in an event.
• Feature
  • Events don't know which components will be affected.
  • Cannot make assumption about order of processing
  • Can have explicit invocations as complementary form of interaction
• Benefits
  • Strong reuse
  • Implicit invocation eases system evolutions
  • Can changing easily
• Disadvantages
  • Relinquish control ( if other components didn't response it then fall the panic)
  • Exchanging data (Global memory using)

    

Layered Architecture

• Def
  • Organized hierarchically, each layer providing service to the layer above layer it and serving to the layer below it.
• Benefits
  • Increasing level of abstractions
  • Enhancements
  • Reuse
• Disadvantages
  • Requiring closer coupling
  • Difficult to find right level of abstractions.

    

Repository (Black boards)

• Def
  • Consist of two kinds of components as follows
    • Central data structure (Current state)
    • Collection of independent component operate on the central data store
• Blackboard Architecture
  • Properties
    • The knowledge sources
      • Separate, independent parcel of applications dependent knowledge
    • The blackboard data structure
      • Problem-solving state data
  • Benefit
    • No explicit representation of the control component

      

Table driven interpreter

• Interpreter's analog of its execution state + pseudo program
• Interpreter components
  • Engine to do works
  • Memory contain pseudo code
  • Representation of the control
  • Representation of the current state