serverless: Add initial implementation of OpenDC Serverless (#100)

This change adds the initial implementation of OpenDC Serverless to the
main repository, which is based on Soufiane Jounaid's work. This commit
introduces the main interfaces into the repository. Later commits will
introduce the other features that Soufiane has implemented previously in
OpenDC.

20 files changed, 1435 insertions, 0 deletions

diff --git a/simulator/opendc-serverless/build.gradle.kts b/simulator/opendc-serverless/build.gradle.kts
new file mode 100644
index 00000000..a458c809
--- /dev/null
+++ b/simulator/opendc-serverless/build.gradle.kts
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2021 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 = "Serverless platform for OpenDC"
diff --git a/simulator/opendc-serverless/opendc-serverless-api/build.gradle.kts b/simulator/opendc-serverless/opendc-serverless-api/build.gradle.kts
new file mode 100644
index 00000000..ec33ccce
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-api/build.gradle.kts
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2021 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 = "Serverless API for OpenDC"
+
+/* Build configuration */
+plugins {
+    `kotlin-library-conventions`
+}
+
+dependencies {
+    api(platform(project(":opendc-platform")))
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-api/src/main/kotlin/org/opendc/serverless/api/ServerlessClient.kt b/simulator/opendc-serverless/opendc-serverless-api/src/main/kotlin/org/opendc/serverless/api/ServerlessClient.kt
new file mode 100644
index 00000000..f14f4977
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-api/src/main/kotlin/org/opendc/serverless/api/ServerlessClient.kt
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2021 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.serverless.api
+
+import java.util.*
+
+/**
+ * Client interface to the OpenDC Serverless service.
+ */
+public interface ServerlessClient : AutoCloseable {
+    /**
+     * Obtain the list of [ServerlessFunction]s accessible by the requesting user.
+     */
+    public suspend fun queryFunctions(): List<ServerlessFunction>
+
+    /**
+     * Obtain a [ServerlessFunction] by its unique identifier.
+     *
+     * @param id The identifier of the flavor.
+     */
+    public suspend fun findFunction(id: UUID): ServerlessFunction?
+
+    /**
+     * Obtain a [ServerlessFunction] by its name.
+     *
+     * @param name The name of the function.
+     */
+    public suspend fun findFunction(name: String): ServerlessFunction?
+
+    /**
+     * Create a new serverless function.
+     *
+     * @param name The name of the function.
+     * @param labels The labels associated with the function.
+     * @param meta The metadata associated with the function.
+     */
+    public suspend fun newFunction(
+        name: String,
+        labels: Map<String, String> = emptyMap(),
+        meta: Map<String, Any> = emptyMap()
+    ): ServerlessFunction
+
+    /**
+     * Invoke the function with the specified [name].
+     */
+    public suspend fun invoke(name: String)
+
+    /**
+     * Release the resources associated with this client, preventing any further API calls.
+     */
+    public override fun close()
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-api/src/main/kotlin/org/opendc/serverless/api/ServerlessFunction.kt b/simulator/opendc-serverless/opendc-serverless-api/src/main/kotlin/org/opendc/serverless/api/ServerlessFunction.kt
new file mode 100644
index 00000000..ec0fad71
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-api/src/main/kotlin/org/opendc/serverless/api/ServerlessFunction.kt
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2021 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.serverless.api
+
+import java.util.UUID
+
+/**
+ * A serverless function instance.
+ */
+public interface ServerlessFunction {
+    /**
+     * The unique identifier of the function.
+     */
+    public val uid: UUID
+
+    /**
+     * The name of the function.
+     */
+    public val name: String
+
+    /**
+     * The identifying labels attached to the resource.
+     */
+    public val labels: Map<String, String>
+
+    /**
+     * The non-identifying metadata attached to the resource.
+     */
+    public val meta: Map<String, Any>
+
+    /**
+     * Invoke the serverless function.
+     */
+    public suspend operator fun invoke()
+
+    /**
+     * Request the function to be deleted.
+     */
+    public suspend fun delete()
+
+    /**
+     * Refresh the local state of this object.
+     */
+    public suspend fun refresh()
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/build.gradle.kts b/simulator/opendc-serverless/opendc-serverless-service/build.gradle.kts
new file mode 100644
index 00000000..bcb08be7
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/build.gradle.kts
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2021 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 = "Serverless service for OpenDC"
+
+/* Build configuration */
+plugins {
+    `kotlin-library-conventions`
+    `testing-conventions`
+    `jacoco-conventions`
+}
+
+dependencies {
+    api(platform(project(":opendc-platform")))
+    api(project(":opendc-serverless:opendc-serverless-api"))
+    api(project(":opendc-trace:opendc-trace-core"))
+    implementation(project(":opendc-utils"))
+    implementation("io.github.microutils:kotlin-logging")
+
+    testImplementation(project(":opendc-simulator:opendc-simulator-core"))
+    testRuntimeOnly("org.apache.logging.log4j:log4j-slf4j-impl")
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/ServerlessService.kt b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/ServerlessService.kt
new file mode 100644
index 00000000..18717ef5
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/ServerlessService.kt
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2021 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.serverless.service
+
+import org.opendc.serverless.api.ServerlessClient
+import org.opendc.serverless.service.deployer.FunctionDeployer
+import org.opendc.serverless.service.internal.ServerlessServiceImpl
+import org.opendc.serverless.service.router.RoutingPolicy
+import java.time.Clock
+import kotlin.coroutines.CoroutineContext
+
+/**
+ * The [ServerlessService] hosts the API implementation of the OpenDC Serverless service.
+ */
+public interface ServerlessService : AutoCloseable {
+    /**
+     * Create a new [ServerlessClient] to control the compute service.
+     */
+    public fun newClient(): ServerlessClient
+
+    /**
+     * Terminate the lifecycle of the serverless service, stopping all running function instances.
+     */
+    public override fun close()
+
+    public companion object {
+        /**
+         * Construct a new [ServerlessService] implementation.
+         *
+         * @param context The [CoroutineContext] to use in the service.
+         * @param clock The clock instance to use.
+         */
+        public operator fun invoke(
+            context: CoroutineContext,
+            clock: Clock,
+            deployer: FunctionDeployer,
+            routingPolicy: RoutingPolicy,
+        ): ServerlessService {
+            return ServerlessServiceImpl(context, clock, deployer, routingPolicy)
+        }
+    }
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/deployer/FunctionDeployer.kt b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/deployer/FunctionDeployer.kt
new file mode 100644
index 00000000..e0a37009
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/deployer/FunctionDeployer.kt
@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2021 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.serverless.service.deployer
+
+import org.opendc.serverless.api.ServerlessFunction
+
+/**
+ * A [FunctionDeployer] is responsible for ensuring that an instance of an arbitrary function, a [FunctionInstance],
+ * is deployed.
+ *
+ * The function deployer should combines the configuration stored in the function registry, the parameters supplied by
+ * the requester, and other factors into a decision of how the function should be deployed, including how many and
+ * what kind of resources it should receive.
+ *
+ * Though it decides how the function instance should be deployed, the deployment of the function instance itself is
+ * delegated to the Resource Orchestration Layer.
+ */
+public interface FunctionDeployer {
+    /**
+     * Deploy the specified [function].
+     */
+    public fun deploy(function: ServerlessFunction): FunctionInstance
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/deployer/FunctionInstance.kt b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/deployer/FunctionInstance.kt
new file mode 100644
index 00000000..410df5d4
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/deployer/FunctionInstance.kt
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2021 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.serverless.service.deployer
+
+import org.opendc.serverless.api.ServerlessFunction
+
+/**
+ * A [FunctionInstance] is a a self-contained worker—typically a container—capable of handling function executions.
+ *
+ * Multiple, concurrent function instances can exists for a single function, for scalability purposes.
+ */
+public interface FunctionInstance : AutoCloseable {
+    /**
+     * The state of the instance.
+     */
+    public val state: FunctionInstanceState
+
+    /**
+     * The [ServerlessFunction] that is represented by this instance.
+     */
+    public val function: ServerlessFunction
+
+    /**
+     * Invoke the function instance.
+     *
+     * This method will suspend execution util the function instance has returned.
+     */
+    public suspend fun invoke()
+
+    /**
+     * Indicate to the resource manager that the instance is not needed anymore and may be cleaned up by the resource
+     * manager.
+     */
+    public override fun close()
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/deployer/FunctionInstanceState.kt b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/deployer/FunctionInstanceState.kt
new file mode 100644
index 00000000..44ad80ee
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/deployer/FunctionInstanceState.kt
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2021 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.serverless.service.deployer
+
+/**
+ * This enumeration describes the states of a [FunctionInstance].
+ */
+public enum class FunctionInstanceState {
+    /**
+     * The function instance is currently being provisioned.
+     */
+    Provisioning,
+
+    /**
+     * The function instance is idle and ready to execute.
+     */
+    Idle,
+
+    /**
+     * The function instance is executing.
+     */
+    Active,
+
+    /**
+     * The function instance is stopped but can be started.
+     */
+    Terminated,
+
+    /**
+     * The function instance is released and cannot be used anymore.
+     */
+    Deleted
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/internal/ClientFunction.kt b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/internal/ClientFunction.kt
new file mode 100644
index 00000000..1258a037
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/internal/ClientFunction.kt
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2021 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.serverless.service.internal
+
+import org.opendc.serverless.api.ServerlessFunction
+import java.util.*
+
+/**
+ * A [ServerlessFunction] implementation that is passed to clients but delegates its implementation to another class.
+ */
+internal class ClientFunction(private val delegate: ServerlessFunction) : ServerlessFunction {
+    override val uid: UUID = delegate.uid
+
+    override var name: String = delegate.name
+        private set
+
+    override var labels: Map<String, String> = delegate.labels.toMap()
+        private set
+
+    override var meta: Map<String, Any> = delegate.meta.toMap()
+        private set
+
+    override suspend fun delete() {
+        delegate.delete()
+    }
+
+    override suspend fun invoke() {
+        delegate.invoke()
+    }
+
+    override suspend fun refresh() {
+        delegate.refresh()
+
+        name = delegate.name
+        labels = delegate.labels
+        meta = delegate.meta
+    }
+
+    override fun equals(other: Any?): Boolean = other is ClientFunction && uid == other.uid
+
+    override fun hashCode(): Int = uid.hashCode()
+
+    override fun toString(): String = "ServerlessFunction[uid=$uid,name=$name]"
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/internal/InternalFunction.kt b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/internal/InternalFunction.kt
new file mode 100644
index 00000000..a6e22912
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/internal/InternalFunction.kt
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2021 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.serverless.service.internal
+
+import org.opendc.serverless.api.ServerlessFunction
+import java.util.*
+
+/**
+ * Internal stateful representation of a [ServerlessFunction].
+ */
+internal class InternalFunction(
+    private val service: ServerlessServiceImpl,
+    override val uid: UUID,
+    name: String,
+    labels: Map<String, String>,
+    meta: Map<String, Any>
+) : ServerlessFunction {
+    override var name: String = name
+        private set
+
+    override val labels: MutableMap<String, String> = labels.toMutableMap()
+
+    override val meta: MutableMap<String, Any> = meta.toMutableMap()
+
+    override suspend fun refresh() {
+        // No-op: this object is the source-of-truth
+    }
+
+    override suspend fun invoke() {
+        service.invoke(this)
+    }
+
+    override suspend fun delete() {
+        service.delete(this)
+    }
+
+    override fun equals(other: Any?): Boolean = other is ServerlessFunction && uid == other.uid
+
+    override fun hashCode(): Int = uid.hashCode()
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/internal/ServerlessServiceImpl.kt b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/internal/ServerlessServiceImpl.kt
new file mode 100644
index 00000000..b3f395c3
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/internal/ServerlessServiceImpl.kt
@@ -0,0 +1,240 @@
+/*
+ * Copyright (c) 2021 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.serverless.service.internal
+
+import kotlinx.coroutines.*
+import kotlinx.coroutines.intrinsics.startCoroutineCancellable
+import mu.KotlinLogging
+import org.opendc.serverless.api.ServerlessClient
+import org.opendc.serverless.api.ServerlessFunction
+import org.opendc.serverless.service.ServerlessService
+import org.opendc.serverless.service.deployer.FunctionDeployer
+import org.opendc.serverless.service.deployer.FunctionInstance
+import org.opendc.serverless.service.router.RoutingPolicy
+import org.opendc.utils.TimerScheduler
+import java.lang.IllegalStateException
+import java.time.Clock
+import java.util.*
+import kotlin.coroutines.Continuation
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.resumeWithException
+
+/**
+ * Implementation of the [ServerlessService] interface.
+ *
+ * This component acts as the function router from the SPEC RG Reference Architecture for FaaS and is responsible
+ * for routing incoming requests or events to the correct [FunctionInstance]. If no [FunctionInstance] is available,
+ * this component queues the events to await the deployment of new instances.
+ */
+internal class ServerlessServiceImpl(
+    context: CoroutineContext,
+    private val clock: Clock,
+    private val deployer: FunctionDeployer,
+    private val routingPolicy: RoutingPolicy
+) : ServerlessService {
+    /**
+     * The [CoroutineScope] of the service bounded by the lifecycle of the service.
+     */
+    private val scope = CoroutineScope(context + Job())
+
+    /**
+     * The logger instance of this server.
+     */
+    private val logger = KotlinLogging.logger {}
+
+    /**
+     * The [TimerScheduler] to use for scheduling the scheduler cycles.
+     */
+    private val scheduler: TimerScheduler<Unit> = TimerScheduler(scope.coroutineContext, clock)
+
+    /**
+     * The [Random] instance used to generate unique identifiers for the objects.
+     */
+    private val random = Random(0)
+
+    /**
+     * The registered functions for this service.
+     */
+    private val functions = mutableMapOf<UUID, InternalFunction>()
+    private val functionsByName = mutableMapOf<String, InternalFunction>()
+
+    /**
+     * The queue of invocation requests.
+     */
+    private val queue = ArrayDeque<InvocationRequest>()
+
+    /**
+     * The active function instances.
+     */
+    private val instancesByFunction = mutableMapOf<InternalFunction, MutableList<FunctionInstance>>()
+
+    override fun newClient(): ServerlessClient {
+        return object : ServerlessClient {
+            private var isClosed: Boolean = false
+
+            override suspend fun queryFunctions(): List<ServerlessFunction> {
+                check(!isClosed) { "Client is already closed" }
+
+                return functions.values.map { ClientFunction(it) }
+            }
+
+            override suspend fun findFunction(id: UUID): ServerlessFunction? {
+                check(!isClosed) { "Client is already closed" }
+
+                return functions[id]?.let { ClientFunction(it) }
+            }
+
+            override suspend fun findFunction(name: String): ServerlessFunction? {
+                check(!isClosed) { "Client is already closed" }
+
+                return functionsByName[name]?.let { ClientFunction(it) }
+            }
+
+            override suspend fun newFunction(
+                name: String,
+                labels: Map<String, String>,
+                meta: Map<String, Any>
+            ): ServerlessFunction {
+                check(!isClosed) { "Client is already closed" }
+                require(name !in functionsByName) { "Function with same name exists" }
+
+                val uid = UUID(clock.millis(), random.nextLong())
+                val function = InternalFunction(
+                    this@ServerlessServiceImpl,
+                    uid,
+                    name,
+                    labels,
+                    meta
+                )
+
+                functionsByName[name] = function
+                functions[uid] = function
+
+                return ClientFunction(function)
+            }
+
+            override suspend fun invoke(name: String) {
+                check(!isClosed) { "Client is already closed" }
+
+                requireNotNull(functionsByName[name]) { "Unknown function" }.invoke()
+            }
+
+            override fun close() {
+                isClosed = true
+            }
+        }
+    }
+
+    /**
+     * Indicate that a new scheduling cycle is needed due to a change to the service's state.
+     */
+    private fun schedule() {
+        // Bail out in case we have already requested a new cycle or the queue is empty.
+        if (scheduler.isTimerActive(Unit) || queue.isEmpty()) {
+            return
+        }
+
+        val quantum = 1000
+
+        // We assume that the provisioner runs at a fixed slot every time quantum (e.g t=0, t=60, t=120).
+        // This is important because the slices of the VMs need to be aligned.
+        // We calculate here the delay until the next scheduling slot.
+        val delay = quantum - (clock.millis() % quantum)
+
+        scheduler.startSingleTimer(Unit, delay, ::doSchedule)
+    }
+
+    /**
+     * Run a single scheduling iteration.
+     */
+    @OptIn(InternalCoroutinesApi::class)
+    private fun doSchedule() {
+        try {
+            while (queue.isNotEmpty()) {
+                val (function, cont) = queue.poll()
+
+                val instances = instancesByFunction[function]
+
+                // Check if there exists an instance of the function
+                val activeInstance = if (instances != null && instances.isNotEmpty()) {
+                    routingPolicy.select(instances, function)
+                } else {
+                    null
+                }
+
+                val instance = if (activeInstance != null) {
+                    activeInstance
+                } else {
+                    val instance = deployer.deploy(function)
+                    instancesByFunction.compute(function) { _, v ->
+                        if (v != null) {
+                            v.add(instance)
+                            v
+                        } else {
+                            mutableListOf(instance)
+                        }
+                    }
+
+                    instance
+                }
+
+                // Invoke the function instance
+                suspend { instance.invoke() }.startCoroutineCancellable(cont)
+            }
+        } catch (cause: Throwable) {
+            logger.error(cause) { "Exception occurred during scheduling cycle" }
+        }
+    }
+
+    internal suspend fun invoke(function: InternalFunction) {
+        check(function.uid in functions) { "Function does not exist (anymore)" }
+
+        return suspendCancellableCoroutine { cont ->
+            if (!queue.add(InvocationRequest(function, cont))) {
+                cont.resumeWithException(IllegalStateException("Failed to enqueue request"))
+            } else {
+                schedule()
+            }
+        }
+    }
+
+    internal fun delete(function: InternalFunction) {
+        functions.remove(function.uid)
+        functionsByName.remove(function.name)
+    }
+
+    override fun close() {
+        scope.cancel()
+
+        // Stop all function instances
+        for ((_, instances) in instancesByFunction) {
+            instances.forEach(FunctionInstance::close)
+        }
+        instancesByFunction.clear()
+    }
+
+    /**
+     * A request to invoke a function.
+     */
+    private data class InvocationRequest(val function: InternalFunction, val cont: Continuation<Unit>)
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/router/RandomRoutingPolicy.kt b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/router/RandomRoutingPolicy.kt
new file mode 100644
index 00000000..015704ca
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/router/RandomRoutingPolicy.kt
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021 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.serverless.service.router
+
+import org.opendc.serverless.api.ServerlessFunction
+import org.opendc.serverless.service.deployer.FunctionInstance
+import kotlin.random.Random
+
+/**
+ * A [RoutingPolicy] that selects a random function instance.
+ */
+public class RandomRoutingPolicy(private val random: Random = Random(0)) : RoutingPolicy {
+    override fun select(instances: List<FunctionInstance>, function: ServerlessFunction): FunctionInstance {
+        return instances.random(random)
+    }
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/router/RoutingPolicy.kt b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/router/RoutingPolicy.kt
new file mode 100644
index 00000000..77f43059
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/src/main/kotlin/org/opendc/serverless/service/router/RoutingPolicy.kt
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021 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.serverless.service.router
+
+import org.opendc.serverless.api.ServerlessFunction
+import org.opendc.serverless.service.deployer.FunctionInstance
+
+/**
+ * A [RoutingPolicy] decides to which [FunctionInstance] a function invocation should be routed.
+ */
+public interface RoutingPolicy {
+    /**
+     * Select the instance to which the request should be routed to.
+     */
+    public fun select(instances: List<FunctionInstance>, function: ServerlessFunction): FunctionInstance?
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-service/src/test/kotlin/org/opendc/serverless/service/ServerlessServiceTest.kt b/simulator/opendc-serverless/opendc-serverless-service/src/test/kotlin/org/opendc/serverless/service/ServerlessServiceTest.kt
new file mode 100644
index 00000000..d9c2bcd2
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-service/src/test/kotlin/org/opendc/serverless/service/ServerlessServiceTest.kt
@@ -0,0 +1,186 @@
+/*
+ * Copyright (c) 2021 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.serverless.service
+
+import io.mockk.*
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.runBlockingTest
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertDoesNotThrow
+import org.junit.jupiter.api.assertThrows
+import org.opendc.serverless.api.ServerlessFunction
+import org.opendc.serverless.service.deployer.FunctionDeployer
+import org.opendc.serverless.service.deployer.FunctionInstance
+import org.opendc.serverless.service.deployer.FunctionInstanceState
+import org.opendc.simulator.utils.DelayControllerClockAdapter
+import java.util.*
+
+/**
+ * Test suite for the [ServerlessService] implementation.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+internal class ServerlessServiceTest {
+
+    @Test
+    fun testClientState() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val service = ServerlessService(coroutineContext, clock, mockk(), mockk())
+
+        val client = assertDoesNotThrow { service.newClient() }
+        assertDoesNotThrow { client.close() }
+
+        assertThrows<IllegalStateException> { client.queryFunctions() }
+        assertThrows<IllegalStateException> { client.newFunction("test") }
+        assertThrows<IllegalStateException> { client.invoke("test") }
+        assertThrows<IllegalStateException> { client.findFunction(UUID.randomUUID()) }
+        assertThrows<IllegalStateException> { client.findFunction("name") }
+    }
+
+    @Test
+    fun testClientInvokeUnknown() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val service = ServerlessService(coroutineContext, clock, mockk(), mockk())
+
+        val client = service.newClient()
+
+        assertThrows<IllegalArgumentException> { client.invoke("test") }
+    }
+
+    @Test
+    fun testClientFunctionCreation() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val service = ServerlessService(coroutineContext, clock, mockk(), mockk())
+
+        val client = service.newClient()
+
+        val function = client.newFunction("test")
+
+        assertEquals("test", function.name)
+    }
+
+    @Test
+    fun testClientFunctionQuery() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val service = ServerlessService(coroutineContext, clock, mockk(), mockk())
+
+        val client = service.newClient()
+
+        assertEquals(emptyList<ServerlessFunction>(), client.queryFunctions())
+
+        val function = client.newFunction("test")
+
+        assertEquals(listOf(function), client.queryFunctions())
+    }
+
+    @Test
+    fun testClientFunctionFindById() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val service = ServerlessService(coroutineContext, clock, mockk(), mockk())
+
+        val client = service.newClient()
+
+        assertEquals(emptyList<ServerlessFunction>(), client.queryFunctions())
+
+        val function = client.newFunction("test")
+
+        assertNotNull(client.findFunction(function.uid))
+    }
+
+    @Test
+    fun testClientFunctionFindByName() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val service = ServerlessService(coroutineContext, clock, mockk(), mockk())
+
+        val client = service.newClient()
+
+        assertEquals(emptyList<ServerlessFunction>(), client.queryFunctions())
+
+        val function = client.newFunction("test")
+
+        assertNotNull(client.findFunction(function.name))
+    }
+
+    @Test
+    fun testClientFunctionDuplicateName() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val service = ServerlessService(coroutineContext, clock, mockk(), mockk())
+
+        val client = service.newClient()
+
+        client.newFunction("test")
+
+        assertThrows<IllegalArgumentException> { client.newFunction("test") }
+    }
+
+    @Test
+    fun testClientFunctionDelete() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val service = ServerlessService(coroutineContext, clock, mockk(), mockk())
+
+        val client = service.newClient()
+        val function = client.newFunction("test")
+        assertNotNull(client.findFunction(function.uid))
+        function.delete()
+        assertNull(client.findFunction(function.uid))
+
+        // Delete should be idempotent
+        function.delete()
+    }
+
+    @Test
+    fun testClientFunctionCannotInvokeDeleted() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val service = ServerlessService(coroutineContext, clock, mockk(), mockk())
+
+        val client = service.newClient()
+        val function = client.newFunction("test")
+        assertNotNull(client.findFunction(function.uid))
+        function.delete()
+
+        assertThrows<IllegalStateException> { function.invoke() }
+    }
+
+    @Test
+    fun testClientFunctionInvoke() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val deployer = mockk<FunctionDeployer>()
+        val service = ServerlessService(coroutineContext, clock, deployer, mockk())
+
+        every { deployer.deploy(any()) } answers {
+            object : FunctionInstance {
+                override val state: FunctionInstanceState = FunctionInstanceState.Idle
+                override val function: ServerlessFunction = it.invocation.args[0] as ServerlessFunction
+
+                override suspend fun invoke() {}
+
+                override fun close() {}
+            }
+        }
+
+        val client = service.newClient()
+        val function = client.newFunction("test")
+
+        function.invoke()
+    }
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-simulator/build.gradle.kts b/simulator/opendc-serverless/opendc-serverless-simulator/build.gradle.kts
new file mode 100644
index 00000000..fe3dca41
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-simulator/build.gradle.kts
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2021 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 = "Simulator for OpenDC Serverles"
+
+/* Build configuration */
+plugins {
+    `kotlin-library-conventions`
+    `testing-conventions`
+    `jacoco-conventions`
+}
+
+dependencies {
+    api(platform(project(":opendc-platform")))
+    api(project(":opendc-serverless:opendc-serverless-service"))
+    api(project(":opendc-simulator:opendc-simulator-compute"))
+
+    testImplementation(project(":opendc-simulator:opendc-simulator-core"))
+    testRuntimeOnly("org.slf4j:slf4j-simple:${versions.slf4j}")
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-simulator/src/main/kotlin/org/opendc/serverless/simulator/SimFunctionDeployer.kt b/simulator/opendc-serverless/opendc-serverless-simulator/src/main/kotlin/org/opendc/serverless/simulator/SimFunctionDeployer.kt
new file mode 100644
index 00000000..7a48609c
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-simulator/src/main/kotlin/org/opendc/serverless/simulator/SimFunctionDeployer.kt
@@ -0,0 +1,159 @@
+/*
+ * Copyright (c) 2021 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.serverless.simulator
+
+import kotlinx.coroutines.*
+import kotlinx.coroutines.channels.Channel
+import org.opendc.serverless.api.ServerlessFunction
+import org.opendc.serverless.service.deployer.FunctionDeployer
+import org.opendc.serverless.service.deployer.FunctionInstance
+import org.opendc.serverless.service.deployer.FunctionInstanceState
+import org.opendc.serverless.simulator.workload.SimServerlessWorkloadMapper
+import org.opendc.simulator.compute.SimBareMetalMachine
+import org.opendc.simulator.compute.SimMachine
+import org.opendc.simulator.compute.SimMachineModel
+import java.time.Clock
+import java.util.ArrayDeque
+import kotlin.coroutines.Continuation
+import kotlin.coroutines.resume
+import kotlin.coroutines.resumeWithException
+
+/**
+ * A [FunctionDeployer] that uses that simulates the [FunctionInstance]s.
+ */
+public class SimFunctionDeployer(
+    private val clock: Clock,
+    private val scope: CoroutineScope,
+    private val model: SimMachineModel,
+    private val mapper: SimServerlessWorkloadMapper
+) : FunctionDeployer {
+
+    override fun deploy(function: ServerlessFunction): Instance {
+        val instance = Instance(function)
+        instance.start()
+        return instance
+    }
+
+    /**
+     * A simulated [FunctionInstance].
+     */
+    public inner class Instance(override val function: ServerlessFunction) : FunctionInstance {
+        /**
+         * The workload associated with this instance.
+         */
+        private val workload = mapper.createWorkload(function)
+
+        /**
+         * The machine that will execute the workloads.
+         */
+        public val machine: SimMachine = SimBareMetalMachine(scope.coroutineContext, clock, model)
+
+        /**
+         * The job associated with the lifecycle of the instance.
+         */
+        private var job: Job? = null
+
+        /**
+         * The invocation request queue.
+         */
+        private val queue = ArrayDeque<InvocationRequest>()
+
+        /**
+         * A channel used to signal that new invocations have been enqueued.
+         */
+        private val chan = Channel<Unit>(Channel.RENDEZVOUS)
+
+        override var state: FunctionInstanceState = FunctionInstanceState.Provisioning
+
+        override suspend fun invoke() {
+            check(state != FunctionInstanceState.Deleted) { "Function instance has been released" }
+            return suspendCancellableCoroutine { cont ->
+                queue.add(InvocationRequest(cont))
+                chan.offer(Unit)
+            }
+        }
+
+        override fun close() {
+            state = FunctionInstanceState.Deleted
+            stop()
+            machine.close()
+        }
+
+        override fun toString(): String = "FunctionInstance[state=$state]"
+
+        /**
+         * Start the function instance.
+         */
+        @OptIn(InternalCoroutinesApi::class)
+        internal fun start() {
+            check(state == FunctionInstanceState.Provisioning) { "Invalid state of function instance" }
+            job = scope.launch {
+                workload.onStart()
+
+                try {
+                    while (isActive) {
+                        chan.receive()
+
+                        if (queue.isNotEmpty()) {
+                            state = FunctionInstanceState.Active
+                        }
+
+                        while (queue.isNotEmpty()) {
+                            val request = queue.poll()
+                            try {
+                                machine.run(workload.onInvoke())
+                                request.cont.resume(Unit)
+                            } catch (cause: CancellationException) {
+                                request.cont.resumeWithException(cause)
+                                throw cause
+                            } catch (cause: Throwable) {
+                                request.cont.resumeWithException(cause)
+                            }
+                        }
+                        state = FunctionInstanceState.Idle
+                    }
+                } finally {
+                    state = FunctionInstanceState.Terminated
+                    workload.onStop()
+                }
+            }
+        }
+
+        /**
+         * Stop the function instance.
+         */
+        private fun stop() {
+            val job = job
+
+            if (job != null) {
+                this.job = null
+                job.cancel()
+            }
+        }
+    }
+
+    /**
+     * A function invocation request.
+     */
+    private data class InvocationRequest(val cont: Continuation<Unit>)
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-simulator/src/main/kotlin/org/opendc/serverless/simulator/workload/SimServerlessWorkload.kt b/simulator/opendc-serverless/opendc-serverless-simulator/src/main/kotlin/org/opendc/serverless/simulator/workload/SimServerlessWorkload.kt
new file mode 100644
index 00000000..afdc05af
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-simulator/src/main/kotlin/org/opendc/serverless/simulator/workload/SimServerlessWorkload.kt
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2021 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.serverless.simulator.workload
+
+import org.opendc.simulator.compute.workload.SimWorkload
+
+/**
+ * A model for a serverless workload, which may be invoked multiple times.
+ */
+public interface SimServerlessWorkload {
+    /**
+     * This method is invoked when a function instance is launched.
+     */
+    public fun onStart() {}
+
+    /**
+     * This method is invoked when an active function instance is invoked.
+     */
+    public fun onInvoke(): SimWorkload
+
+    /**
+     * This method is invoked when the function instance is stopped.
+     */
+    public fun onStop() {}
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-simulator/src/main/kotlin/org/opendc/serverless/simulator/workload/SimServerlessWorkloadMapper.kt b/simulator/opendc-serverless/opendc-serverless-simulator/src/main/kotlin/org/opendc/serverless/simulator/workload/SimServerlessWorkloadMapper.kt
new file mode 100644
index 00000000..670f978d
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-simulator/src/main/kotlin/org/opendc/serverless/simulator/workload/SimServerlessWorkloadMapper.kt
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021 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.serverless.simulator.workload
+
+import org.opendc.serverless.api.ServerlessFunction
+
+/**
+ * A [SimServerlessWorkloadMapper] is responsible for mapping a [ServerlessFunction] to a [SimServerlessWorkload] that
+ * can be simulated.
+ */
+public fun interface SimServerlessWorkloadMapper {
+    /**
+     * Map the specified [function] to a [SimServerlessWorkload] that can be simulated.
+     */
+    public fun createWorkload(function: ServerlessFunction): SimServerlessWorkload
+}
diff --git a/simulator/opendc-serverless/opendc-serverless-simulator/src/test/kotlin/org/opendc/serverless/simulator/SimServerlessServiceTest.kt b/simulator/opendc-serverless/opendc-serverless-simulator/src/test/kotlin/org/opendc/serverless/simulator/SimServerlessServiceTest.kt
new file mode 100644
index 00000000..a80365de
--- /dev/null
+++ b/simulator/opendc-serverless/opendc-serverless-simulator/src/test/kotlin/org/opendc/serverless/simulator/SimServerlessServiceTest.kt
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2021 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.serverless.simulator
+
+import io.mockk.spyk
+import io.mockk.verify
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.test.runBlockingTest
+import kotlinx.coroutines.yield
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertAll
+import org.opendc.serverless.service.ServerlessService
+import org.opendc.serverless.service.router.RandomRoutingPolicy
+import org.opendc.serverless.simulator.workload.SimServerlessWorkload
+import org.opendc.simulator.compute.SimMachineModel
+import org.opendc.simulator.compute.model.SimMemoryUnit
+import org.opendc.simulator.compute.model.SimProcessingNode
+import org.opendc.simulator.compute.model.SimProcessingUnit
+import org.opendc.simulator.compute.workload.SimFlopsWorkload
+import org.opendc.simulator.compute.workload.SimWorkload
+import org.opendc.simulator.utils.DelayControllerClockAdapter
+
+/**
+ * A test suite for the [ServerlessService] implementation under simulated conditions.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+internal class SimServerlessServiceTest {
+
+    private lateinit var machineModel: SimMachineModel
+
+    @BeforeEach
+    fun setUp() {
+        val cpuNode = SimProcessingNode("Intel", "Xeon", "amd64", 2)
+
+        machineModel = SimMachineModel(
+            cpus = List(cpuNode.coreCount) { SimProcessingUnit(cpuNode, it, 1000.0) },
+            memory = List(4) { SimMemoryUnit("Crucial", "MTA18ASF4G72AZ-3G2B1", 3200.0, 32_000) }
+        )
+    }
+
+    @Test
+    fun testSmoke() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+        val workload = spyk(object : SimServerlessWorkload {
+            override fun onInvoke(): SimWorkload = SimFlopsWorkload(1000)
+        })
+        val deployer = SimFunctionDeployer(clock, this, machineModel) { workload }
+        val service = ServerlessService(coroutineContext, clock, deployer, RandomRoutingPolicy())
+
+        val client = service.newClient()
+
+        val function = client.newFunction("test")
+        function.invoke()
+        delay(2000)
+
+        service.close()
+
+        yield()
+
+        assertAll(
+            { verify { workload.onStart() } },
+            { verify { workload.onInvoke() } },
+            { verify { workload.onStop() } }
+        )
+    }
+}