Blackboard (design pattern)

Short description: Type of design pattern

In software engineering, the blackboard pattern is a behavioral design pattern^[1] that provides a computational framework for the design and implementation of systems that integrate large and diverse specialized modules, and implement complex, non-deterministic control strategies.^[2]^[1]

This pattern was identified by the members of the Hearsay-II project and first applied to speech recognition.^[2]

Structure

The blackboard model defines three main components:

blackboard—a structured global memory containing objects from the solution space
knowledge sources—specialized modules with their own representation
control component—selects, configures and executes modules.^[2]

Implementation

The first step is to design the solution space (i.e. potential solutions) that leads to the blackboard structure. Then, knowledge sources are identified. These two activities are closely related.^[2]

The next step is to specify the control component; it generally takes the form of a complex scheduler that makes use of a set of domain-specific heuristics to rate the relevance of executable knowledge sources.^[2]

System Structure^[2]

Applications

Usage-domains include:

speech recognition
vehicle identification and tracking
protein structure identification
sonar signals interpretation.^[2]

Consequences

The blackboard pattern provides effective solutions for designing and implementing complex systems where heterogeneous modules have to be dynamically combined to solve a problem. This provides non-functional properties such as:

reusability
changeability
robustness.^[2]

The blackboard pattern allows multiple processes to work closer together on separate threads, polling and reacting when necessary.^[1]

References

↑ ^1.0 ^1.1 ^1.2 "Blackboard Design Pattern". Microsoft. http://social.technet.microsoft.com/wiki/contents/articles/13215.blackboard-design-pattern.aspx.
↑ ^2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 ^2.6 ^2.7 Lalanda, P., Two complementary patterns to build multi-expert systems, Orsay, France: Thomson CSF Corporate Research Laboratory

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Original source: https://en.wikipedia.org/wiki/Blackboard (design pattern). Read more

[:m_bdp-1] 1.0 ^1.1 ^1.2 "Blackboard Design Pattern". Microsoft. http://social.technet.microsoft.com/wiki/contents/articles/13215.blackboard-design-pattern.aspx.

[:tcpbms-2] 2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 ^2.6 ^2.7 Lalanda, P., Two complementary patterns to build multi-expert systems, Orsay, France: Thomson CSF Corporate Research Laboratory

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[2]

v t e Software design patterns
Creational	Abstract factory Builder Dependency injection Factory method Lazy initialization Multiton Object pool Prototype RAII Singleton
Structural	Adapter Bridge Composite Decorator Delegation Facade Flyweight Front controller Marker interface Module Proxy Twin
Behavioral	Blackboard Chain of responsibility Command Interpreter Iterator Mediator Memento Null object Observer Servant Specification State Strategy Template method Visitor
Functional	Closure Currying Function composition Functor Monad Generator
Concurrency	Active object Actor Balking Barrier Binding properties Coroutine Compute kernel Double-checked locking Event-based asynchronous Fiber Futex Futures and promises Guarded suspension Immutable object Join Lock Messaging Monitor Nuclear Proactor Reactor Read write lock Scheduler Thread pool Thread-local storage
Architectural	ADR Active record Broker Client–server CBD DAO DTO DDD ECB ECS EDA Front controller Identity map Interceptor Implicit invocation Inversion of control Model 2 MOM Microservices MVA MVC MVP MVVM Monolithic Multitier Naked objects ORB P2P Publish–subscribe PAC REST SOA Service locator SN SBA Specification
Cloud Distributed	Ambassador Anti-Corruption Layer Bulkhead Cache-Aside Circuit Breaker CQRS Compensating Transaction Competing Consumers Compute Resource Consolidation Event Sourcing External Configuration Store Federated Identity Gatekeeper Index Table Leader Election MapReduce Materialized View Pipes Filters Priority Queue Publisher-Subscriber Queue-Based Load Leveling Retry Scheduler Agent Supervisor Sharding Sidecar Strangler Throttling Valet Key
Other	Business delegate Composite entity Intercepting filter Lazy loading Mangler Mock object Type tunnel Method chaining
Books	Design Patterns Enterprise Integration Patterns
People	Christopher Alexander Erich Gamma Ralph Johnson John Vlissides Grady Booch Kent Beck Ward Cunningham Martin Fowler Robert Martin Jim Coplien Douglas Schmidt Linda Rising
Communities	The Hillside Group The Portland Pattern Repository