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Chapter 6, image, image, image - Coggle Diagram
Chapter 6
Blackboard Architecture Style
Flow of logic is determined by the current data status
The clients of a blackboard system are called
Knowledge sources
Listeners or subscribers
A new data change may trigger events so that the knowledge sources take actions to respond to these events. These actions may result in new data and change in logic flow
A new data change may trigger events so that the knowledge sources take actions to respond to these events
Example
Knowledge-based AI system
voice and image recognition system
Blackboard system:
A common knowledge base, the "blackboard", is iteratively updated by a diverse knowledge sources,
starting with a problem specification and ending with a solution.
Blackboard
Data store is active
Clients are inactive/passive
A UML diagram for rule-based blackboard software
Blackboard Arch. in Box-Line
Properties
They don’t need to interact with each other
Only interact and respond to the blackboard subsystem
Each knowledge source is relatively independent
Blackboard Arch. in Box-Line
How to Solve Problems
Both can use the blackboard arch.
Facts in blackboard
Rules in agents
Example: forward reasoning
F2 matches R1 produces new fact F6: it is carnivore
F1 matches R2 produces new fact F5: it is a mammal
F5,F6,F3,F4 matches R3 produces the result
Two major approaches
Backward Reasoning
Backward Reasoning
Another Example: Travel Reservation
Travel Consulting System
Process
Once air reservation data is returned and stored in blackboard, the change triggers hotel, auto rental, attraction agents for a travel plans under budge and time
Client chooses one of the plan
The blackboard makes a request to the air agent
The system triggers the billing process
The system stores all the data in the blackboard
Two major approaches
A client submits a request
Data-Centered Software Architecture
Repository
Student Record DB
It describes the static relationships between data classes and their collection classes
It describes the static relationships between data classes and their backup database tables
A programming oriented view of the repository design architecture
Repository Style
Each agent might have different interface, functionality, privilege
Dash line means clients have full control over logic flow
Clients of the data store are active
Examples
Interface repository in CORBA
Library Information system
Database management system
Client may access the repository
Batch transaction
Interactively
Its clients taking control of flow logic
Data store is passive
Variants of Data Repository
Virtual repository
Built up on the top of multiple physical repositories
Most DB allows users to create views that are virtual repositories since they do not exist physically
Benefits
Simplify the overall complexity of overall database structure
Security management in terms of scope of data of manipulation for different users
Distributed repository system (distributed database system)
All data are distributed over all sites linked by network
Data are replicated in order to
Improve reliability and local accessibility
Other issues - concerns
Synchronization of duplicated data
Cost of data transmission
Vertical or horizontal partitions
Collaboration (two-phase transaction commitment)
