CODESAMPLE

Blackboard - Kotlin

Blackboard Kotlin

The Blackboard pattern is a computational architecture for solving complex problems by allowing multiple knowledge sources (agents) to interact through a shared data repository (the blackboard). Agents independently examine the blackboard and contribute information when they detect relevant data. This promotes loose coupling and allows agents to be added or removed without impacting others.

This Kotlin example creates a simplified Blackboard system for recognizing “patterns” in strings. The Blackboard holds the data (input string) and knowledge (recognized patterns). Agents define condition (when to act) and action (what to contribute). The run function simulates the processing loop, where agents check and update the blackboard until a termination condition is met, or a maximum number of iterations is reached. Kotlin’s functional approach with lambda expressions cleanly defines the agent’s logic, and data classes promote immutability and clarity, fitting the language’s style.

data class Blackboard(var data: String, var knowledge: MutableList<String> = mutableListOf())

interface Agent {
    val condition: (Blackboard) -> Boolean
    val action: (Blackboard) -> Unit
}

fun runBlackboard(initialData: String, agents: List<Agent>, maxIterations: Int = 10): Blackboard {
    val blackboard = Blackboard(initialData)
    var iteration = 0

    while (iteration < maxIterations && blackboard.knowledge.isEmpty()) {
        for (agent in agents) {
            if (agent.condition(blackboard)) {
                agent.action(blackboard)
            }
        }
        iteration++
    }

    return blackboard
}

fun main() {
    val blackboard = runBlackboard("hello world") {
        val agents = listOf(
            object : Agent {
                override val condition: (Blackboard) -> Boolean = { it.data.contains("hello") }
                override val action: (Blackboard) -> Unit = { it.knowledge.add("Greeting detected") }
            },
            object : Agent {
                override val condition: (Blackboard) -> Boolean = { it.data.contains("world") }
                override val action: (Blackboard) -> Unit = { it.knowledge.add("World detected") }
            }
        )
        runBlackboard("hello world", agents)
    }

    println("Data: ${blackboard.data}")
    println("Knowledge: ${blackboard.knowledge}")
}