merge: Add provisioning tool for experiments (#104)

This pull request implements a new tool to help provision and manage the 
experimental environment.

## Implementation Notes :hammer_and_pick:

* Add service registry for cloud services 
* Add provisioning tool for experiments
* Add provisioning step for workflow service 
* Add provisioners for FaaS service 
* Use experiment base for Capelin experiments
* Use experiment base for web runner
* Integrate compute workload classes
* Remove Topology interface 

## Breaking API Changes :warning:

* Removal of the `opendc-compute-workload`, `opendc-faas-workload`, 
   and `opendc-workflow-workload` modules. These are now located 
   inside `opendc-experiments`
* Removal of `ComputeServiceHelper`. Use `Provisioner` to provision 
   a `ComputeService`.

8 files changed, 535 insertions, 0 deletions

diff --git a/opendc-experiments/opendc-experiments-base/build.gradle.kts b/opendc-experiments/opendc-experiments-base/build.gradle.kts
new file mode 100644
index 00000000..2cce8c1c
--- /dev/null
+++ b/opendc-experiments/opendc-experiments-base/build.gradle.kts
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2022 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+description = "Experiment base for OpenDC"
+
+/* Build configuration */
+plugins {
+    `kotlin-library-conventions`
+    `testing-conventions`
+    `jacoco-conventions`
+}
+
+dependencies {
+    api(libs.microprofile.config)
+
+    implementation(projects.opendcSimulator.opendcSimulatorCore)
+}
diff --git a/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/MutableServiceRegistry.kt b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/MutableServiceRegistry.kt
new file mode 100644
index 00000000..160dd393
--- /dev/null
+++ b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/MutableServiceRegistry.kt
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2022 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.experiments
+
+/**
+ * A mutable [ServiceRegistry].
+ */
+public interface MutableServiceRegistry : ServiceRegistry {
+    /**
+     * Register [service] for the specified [name] in this registry.
+     *
+     * @param name The name of the service to register, which should follow the rules for domain names as defined by
+     *             DNS.
+     * @param type The interface provided by the service.
+     * @param service A reference to the actual implementation of the service.
+     */
+    public fun <T : Any> register(name: String, type: Class<T>, service: T)
+
+    /**
+     * Remove the service with [name] and [type] from this registry.
+     *
+     * @param name The name of the service to remove, which should follow the rules for domain names as defined by DNS.
+     * @param type The type of the service to remove.
+     */
+    public fun remove(name: String, type: Class<*>)
+
+    /**
+     * Remove all services registered with [name].
+     *
+     * @param name The name of the services to remove, which should follow the rules for domain names as defined by DNS.
+     */
+    public fun remove(name: String)
+
+    /**
+     * Create a copy of the registry.
+     */
+    public override fun clone(): MutableServiceRegistry
+}
diff --git a/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/ServiceRegistry.kt b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/ServiceRegistry.kt
new file mode 100644
index 00000000..e9d5b50e
--- /dev/null
+++ b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/ServiceRegistry.kt
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2022 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.experiments
+
+/**
+ * A read-only registry of services used during experiments to resolve services.
+ *
+ * The service registry is similar conceptually to the Domain Name System (DNS), which is a naming system used to
+ * identify computers reachable via the Internet. The service registry should be used in a similar fashion.
+ */
+public interface ServiceRegistry {
+    /**
+     * Lookup the service with the specified [name] and [type].
+     *
+     * @param name The name of the service to resolve, which should follow the rules for domain names as defined by DNS.
+     * @param type The type of the service to resolve, identified by the interface that is implemented by the service.
+     * @return The service with specified [name] and implementing [type] or `null` if it does not exist.
+     */
+    public fun <T : Any> resolve(name: String, type: Class<T>): T?
+
+    /**
+     * Create a copy of the registry.
+     */
+    public fun clone(): ServiceRegistry
+}
diff --git a/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/internal/ServiceRegistryImpl.kt b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/internal/ServiceRegistryImpl.kt
new file mode 100644
index 00000000..c2e91730
--- /dev/null
+++ b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/internal/ServiceRegistryImpl.kt
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2022 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.experiments.internal
+
+import org.opendc.experiments.MutableServiceRegistry
+
+/**
+ * Implementation of the [MutableServiceRegistry] interface.
+ */
+internal class ServiceRegistryImpl(private val registry: MutableMap<String, MutableMap<Class<*>, Any>> = mutableMapOf()) :
+    MutableServiceRegistry {
+    override fun <T : Any> resolve(name: String, type: Class<T>): T? {
+        val servicesForName = registry[name] ?: return null
+
+        @Suppress("UNCHECKED_CAST")
+        return servicesForName[type] as T?
+    }
+
+    override fun <T : Any> register(name: String, type: Class<T>, service: T) {
+        val services = registry.computeIfAbsent(name) { mutableMapOf() }
+
+        if (type in services) {
+            throw IllegalStateException("Duplicate service $type registered for name $name")
+        }
+
+        services[type] = service
+    }
+
+    override fun remove(name: String, type: Class<*>) {
+        val services = registry[name] ?: return
+        services.remove(type)
+    }
+
+    override fun remove(name: String) {
+        registry.remove(name)
+    }
+
+    override fun clone(): MutableServiceRegistry {
+        val res = mutableMapOf<String, MutableMap<Class<*>, Any>>()
+        registry.mapValuesTo(res) { (_, v) -> v.toMutableMap() }
+        return ServiceRegistryImpl(res)
+    }
+
+    override fun toString(): String {
+        val entries = registry.map { "${it.key}=${it.value}" }.joinToString()
+        return "ServiceRegistry{$entries}"
+    }
+}
diff --git a/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/provisioner/Provisioner.kt b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/provisioner/Provisioner.kt
new file mode 100644
index 00000000..3a1c3144
--- /dev/null
+++ b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/provisioner/Provisioner.kt
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2022 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.experiments.provisioner
+
+import org.opendc.experiments.MutableServiceRegistry
+import org.opendc.experiments.ServiceRegistry
+import org.opendc.experiments.internal.ServiceRegistryImpl
+import java.time.Clock
+import java.util.*
+import java.util.ArrayDeque
+import kotlin.coroutines.CoroutineContext
+
+/**
+ * A helper class to set up the experimental environment in a reproducible manner.
+ *
+ * With this class, users describe the environment using multiple [ProvisioningStep]s. These re-usable
+ * [ProvisioningStep]s are executed sequentially and ensure that the necessary infrastructure is configured and teared
+ * down after the simulation completes.
+ *
+ * @param coroutineContext The [CoroutineContext] in which the environment is set up.
+ * @param clock The simulation [Clock].
+ * @param seed A seed for initializing the randomness of the environment.
+ */
+public class Provisioner(coroutineContext: CoroutineContext, clock: Clock, seed: Long) : AutoCloseable {
+    /**
+     * Implementation of [ProvisioningContext].
+     */
+    private val context = object : ProvisioningContext {
+        override val clock: Clock = clock
+        override val coroutineContext: CoroutineContext = coroutineContext
+        override val seeder: SplittableRandom = SplittableRandom(seed)
+        override val registry: MutableServiceRegistry = ServiceRegistryImpl()
+
+        override fun toString(): String = "Provisioner.ProvisioningContext"
+    }
+
+    /**
+     * The stack of handles to run during the clean-up process.
+     */
+    private val stack = ArrayDeque<AutoCloseable>()
+
+    /**
+     * The [ServiceRegistry] containing the services registered in this environment.
+     */
+    public val registry: ServiceRegistry
+        get() = context.registry
+
+    /**
+     * Run a single [ProvisioningStep] for this environment.
+     *
+     * @param step The step to apply to the environment.
+     */
+    public fun runStep(step: ProvisioningStep) {
+        val handle = step.apply(context)
+        stack.push(handle)
+    }
+
+    /**
+     * Run multiple [ProvisioningStep]s for this environment.
+     *
+     * @param steps The steps to apply to the environment.
+     */
+    public fun runSteps(vararg steps: ProvisioningStep) {
+        val ctx = context
+        val stack = stack
+        for (step in steps) {
+            val handle = step.apply(ctx)
+            stack.push(handle)
+        }
+    }
+
+    /**
+     * Clean-up the environment.
+     */
+    override fun close() {
+        val stack = stack
+        while (stack.isNotEmpty()) {
+            stack.pop().close()
+        }
+    }
+}
diff --git a/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/provisioner/ProvisioningContext.kt b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/provisioner/ProvisioningContext.kt
new file mode 100644
index 00000000..58f6844d
--- /dev/null
+++ b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/provisioner/ProvisioningContext.kt
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2022 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.experiments.provisioner
+
+import org.opendc.experiments.MutableServiceRegistry
+import java.time.Clock
+import java.util.*
+import kotlin.coroutines.CoroutineContext
+
+/**
+ * The [ProvisioningContext] class provides access to shared state between subsequent [ProvisioningStep]s, as well as
+ * access to the simulation dispatcher (via [CoroutineContext]), the virtual clock, and a randomness seeder to allow
+ * the provisioning steps to initialize the (simulated) resources.
+ */
+public interface ProvisioningContext {
+    /**
+     * The [CoroutineContext] in which the provisioner runs.
+     */
+    public val coroutineContext: CoroutineContext
+
+    /**
+     * The [Clock] tracking the virtual simulation time.
+     */
+    public val clock: Clock
+
+    /**
+     * A [SplittableRandom] instance used to seed the provisioners.
+     */
+    public val seeder: SplittableRandom
+
+    /**
+     * A [MutableServiceRegistry] where the provisioned services are registered.
+     */
+    public val registry: MutableServiceRegistry
+}
diff --git a/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/provisioner/ProvisioningStep.kt b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/provisioner/ProvisioningStep.kt
new file mode 100644
index 00000000..e78f8d4f
--- /dev/null
+++ b/opendc-experiments/opendc-experiments-base/src/main/kotlin/org/opendc/experiments/provisioner/ProvisioningStep.kt
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2022 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.experiments.provisioner
+
+import org.eclipse.microprofile.config.Config
+
+/**
+ * A provisioning step is responsible for provisioning (acquiring or configuring) infrastructure necessary for a
+ * simulation experiment.
+ */
+public fun interface ProvisioningStep {
+    /**
+     * Apply the step by provisioning the required resources for the experiment using the specified
+     * [ProvisioningContext][ctx].
+     *
+     * @param ctx The environment in which the resources should be provisioned.
+     * @return A handle that is invoked once the simulation completes, so that the resources can be cleaned up.
+     */
+    public fun apply(ctx: ProvisioningContext): AutoCloseable
+
+    /**
+     * A factory interface for [ProvisioningStep] instances.
+     *
+     * @param S The type that describes the input for constructing a [ProvisioningStep].
+     */
+    public abstract class Provider<S>(public val type: Class<S>) {
+        /**
+         * The name that identifies the provisioning step.
+         */
+        public abstract val name: String
+
+        /**
+         * Construct a [ProvisioningStep] with the specified [spec].
+         *
+         * @param spec The specification that describes the provisioner to be created.
+         * @param config The external configuration of the experiment runner.
+         * @return The [ProvisioningStep] constructed according to [spec].
+         */
+        public abstract fun create(spec: S, config: Config): ProvisioningStep
+    }
+}
diff --git a/opendc-experiments/opendc-experiments-base/src/test/kotlin/org/opendc/experiments/ServiceRegistryTest.kt b/opendc-experiments/opendc-experiments-base/src/test/kotlin/org/opendc/experiments/ServiceRegistryTest.kt
new file mode 100644
index 00000000..f69c07c1
--- /dev/null
+++ b/opendc-experiments/opendc-experiments-base/src/test/kotlin/org/opendc/experiments/ServiceRegistryTest.kt
@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2022 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.experiments
+
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import org.opendc.experiments.internal.ServiceRegistryImpl
+
+/**
+ * Test suite for the [ServiceRegistry] implementation.
+ */
+class ServiceRegistryTest {
+    @Test
+    fun testRetrievalSuccess() {
+        val registry = ServiceRegistryImpl()
+
+        registry.register("opendc.org", String::class.java, "Comment")
+
+        assertEquals("Comment", registry.resolve("opendc.org", String::class.java))
+    }
+
+    @Test
+    fun testRetrievalFailure() {
+        val registry = ServiceRegistryImpl()
+        assertNull(registry.resolve("opendc.org", String::class.java))
+    }
+
+    @Test
+    fun testDuplicate() {
+        val registry = ServiceRegistryImpl()
+
+        registry.register("opendc.org", String::class.java, "Comment")
+
+        assertThrows<IllegalStateException> { registry.register("opendc.org", String::class.java, "Comment2") }
+    }
+
+    @Test
+    fun testRemove() {
+        val registry = ServiceRegistryImpl()
+
+        registry.register("opendc.org", String::class.java, "Comment")
+        registry.remove("opendc.org", String::class.java)
+
+        assertAll(
+            { assertDoesNotThrow { registry.remove("opendc.org", String::class.java) } },
+            { assertNull(registry.resolve("opendc.org", String::class.java)) }
+        )
+    }
+
+    @Test
+    fun testRemoveNonExistent() {
+        val registry = ServiceRegistryImpl()
+
+        assertAll(
+            { assertNull(registry.resolve("opendc.org", String::class.java)) },
+            { assertDoesNotThrow { registry.remove("opendc.org", String::class.java) } }
+        )
+    }
+
+    @Test
+    fun testRemoveAll() {
+        val registry = ServiceRegistryImpl()
+
+        registry.register("opendc.org", String::class.java, "Comment")
+        registry.register("opendc.org", Int::class.java, 1)
+
+        println(registry)
+
+        registry.remove("opendc.org")
+
+        assertAll(
+            { assertNull(registry.resolve("opendc.org", String::class.java)) },
+            { assertNull(registry.resolve("opendc.org", Int::class.java)) },
+        )
+    }
+
+    @Test
+    fun testClone() {
+        val registry = ServiceRegistryImpl()
+        registry.register("opendc.org", String::class.java, "Comment")
+
+        val clone = registry.clone()
+        clone.remove("opendc.org")
+
+        assertAll(
+            { assertEquals("Comment", registry.resolve("opendc.org", String::class.java)) },
+            { assertNull(clone.resolve("opendc.org", String::class.java)) }
+        )
+    }
+}