Typical Architectural Styles

Typical Architectural Styles

1. Data Flow

   • Used when
     • Data processing plays a significant role
   • Is represented by
     • Computational Model
       • Characterised by
         • Viewing the system as a series of transformations
         • Data flows thourgh components one at a time
         • The structure is dominated by orderly motion of data from component to component
         • Availability of data controls computation
     • Design Vocabulary
       • Consists of
         • Processing Elements
         • Data Flows
     • Structural Pattern
       • Can be viewed as
         • Directed graph
           • Where
             • Nodes
               • Are
                 • Processing Elements
             • Arcs
               • Are
                 • Data Flows
     • Essential Invariants
       • Are
         • There is no interaction between processing elements other than data flows
         • Each processing element must be on a path from the input to an output
     • Sub-types of the style
       • Are
         • Batch sequential processing
         • Pipe-and-Filter
     • Properties Derived from the Architecture
       • Are
         • Components are highly independent
         • Processing elements can be excecuted concurrently
         • Capability of processing continuous streams of data
         • Components are reusable
         • Modification of the system can be easily performed
         • New processing elements and data flows can be easily added

2. Independent Components

   • Is Represented By
     • Computational Model
       • Characterised by
         • Components communicate through messages
           • That can be
             • Passed to named participants
             • Passed among unnamed participantes
     • Design Vocabulary
       • Consists of
         • Processes
         • Modules
     • Essential Invariants
       • Are
         • Only means of information exchange among the components is message passing
         • No shared state or variable between the components
         • Components are autonomous
     • Sub-types of the Style
       • Are
         • Communicating Process
         • Event-based Implicit Invocation
         • Interrupt-driven Process
         • Multi-agent Systems
     • Properties Derived from the Architecture
       • Are
         • Modifiability
         • Concurrent and Parallel execution of the components
         • Scalability of the system
         • Easy component integration
         • Strongly supports system evolution
   • Used When
     • Software reuse is strongly needed
     • Need of easily integrate components

3. Call and Return

   • Used When
     • Implementing a large system
   • Is Represented By
     • Computational Model
       • Characterised by
         • Decomposition into smaller pieces
         • Single thread of control
         • Each component executes only when it gets this control from another component
         • Each component returns the component when the excecution is finished
         • Each component has a fixed entry where de execution starts
         • Each component has fixed exits where the executions terminate
         • There is a component that has the entrance to the whole program called Main Program
     • Design Vocabulary
       • Consists of
         • Main-program-and.subroutine with shared data
         • Modules
         • Subroutines
         • Loose Coupling
         • High Cohesion
         • Granularity
     • Structural Pattern
       • Can be viewed as
         • Topological Structure
           • That links
             • Subroutines
               • By
                 • Subroutine calls
               • Are packeed into
                 • Program Units
     • Sub-types of the Style
       • Are
         • Layered Systems
         • Data Abstraction
           • Decomposed in
             • Abstract Data Types
             • Object Oriented Systems
     • Properties Derived from the Architecture
       • Are
         • Separation of Concerns
         • Information Hiding
         • Modular Programming
         • Modifiability

4. Data Centered

   • It's Represented by
     • Computational Model
       • Characterised by
         • The access and update of a widely accessed data-store is an apt description
     • Design Vocabulary
       • Consists of
         • Data Store
         • Shared Data
         • Clients
     • Structural Pattern
       • Can be viewed as
         • Star Schema
     • Sub-types of the Style
       • Are
         • Passive Repositories
         • Active Repositories (Blackboards)
     • Properties Derived from the Style
       • Are
         • Structural solution to integrability
         • Clients are independent of each other
         • The data store is independent of the clients
         • The system is scalable

5. Virtual Machine

   • It's Represented by
     • Computational Model
       • Characterised By
         • Three passive data components
         • One Active data component
     • Design Vocabulary
       • Consists of
         • Program
         • Instructions/Statements
         • Data
         • Interpretation Engine
         • Internal State
     • Structural Pattern
       • Consists of
         • Data
         • Interpretation Engine
         • Program
         • Internal State
     • Properties Derived form the Architecture
       • Are
         • Portability
         • Flexibility