Add Step classes for usecases controller

Add usecases-specific classes for managing preprocessor steps.

Issue-ID: POLICY-2748
Change-Id: I62a2bf8fbeb656a5017531a3f3de6a6dbad5a004
Signed-off-by: Jim Hahn <jrh3@att.com>

7 files changed, 909 insertions, 0 deletions

diff --git a/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/AaiCqStep2.java b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/AaiCqStep2.java
new file mode 100644
index 000000000..9ae1d7fb0
--- /dev/null
+++ b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/AaiCqStep2.java
@@ -0,0 +1,66 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.drools.apps.controller.usecases.step;
+
+import org.onap.policy.aai.AaiCqResponse;
+import org.onap.policy.controlloop.actor.aai.AaiActor;
+import org.onap.policy.controlloop.actor.aai.AaiCustomQueryOperation;
+import org.onap.policy.controlloop.actorserviceprovider.OperationOutcome;
+
+/**
+ * Wrapper for {@link AaiCustomQueryOperation}. The {@link #success(OperationOutcome)}
+ * method stores the resultant "tenant" object in the step's context.
+ */
+public class AaiCqStep2 extends Step2 {
+
+    /**
+     * Constructs the object using information from another step.
+     *
+     * @param otherStep step whose information should be used
+     */
+    public AaiCqStep2(Step2 otherStep) {
+        super(otherStep, AaiActor.NAME, AaiCustomQueryOperation.NAME);
+    }
+
+    /**
+     * Skips the operation if we already have the data.
+     */
+    @Override
+    public boolean start(long remainingMs) {
+        if (stepContext.contains(AaiCqResponse.CONTEXT_KEY)) {
+            // already have the data
+            return false;
+        }
+
+        return super.start(remainingMs);
+    }
+
+    /**
+     * Saves the response for later use.
+     */
+    @Override
+    public void success(OperationOutcome outcome) {
+        AaiCqResponse resp = outcome.getResponse();
+        stepContext.setProperty(AaiCqResponse.CONTEXT_KEY, resp);
+
+        super.success(outcome);
+    }
+}
diff --git a/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/AaiGetPnfStep2.java b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/AaiGetPnfStep2.java
new file mode 100644
index 000000000..131daef9d
--- /dev/null
+++ b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/AaiGetPnfStep2.java
@@ -0,0 +1,70 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.drools.apps.controller.usecases.step;
+
+import org.onap.policy.common.utils.coder.StandardCoderObject;
+import org.onap.policy.controlloop.actor.aai.AaiActor;
+import org.onap.policy.controlloop.actor.aai.AaiGetPnfOperation;
+import org.onap.policy.controlloop.actorserviceprovider.OperationOutcome;
+
+/**
+ * Wrapper for {@link AaiGetPnfOperation}. The {@link #success(OperationOutcome)} method
+ * stores the resultant PNF object in the step's context.
+ * <p/>
+ * Note: this assumes that the target entity is one of the properties returned by
+ * {@link AaiGetPnfOperation#getPropertyNames()}.
+ */
+public class AaiGetPnfStep2 extends Step2 {
+
+
+    /**
+     * Constructs the object using information from another step.
+     *
+     * @param otherStep step whose information should be used
+     */
+    public AaiGetPnfStep2(Step2 otherStep) {
+        super(otherStep, AaiActor.NAME, AaiGetPnfOperation.NAME);
+    }
+
+    /**
+     * Skips the operation if we already have the data.
+     */
+    @Override
+    public boolean start(long remainingMs) {
+        if (stepContext.contains(AaiGetPnfOperation.getKey(getTargetEntity()))) {
+            // already have the data
+            return false;
+        }
+
+        return super.start(remainingMs);
+    }
+
+    /**
+     * Saves the response for later use.
+     */
+    @Override
+    public void success(OperationOutcome outcome) {
+        StandardCoderObject resp = outcome.getResponse();
+        stepContext.setProperty(AaiGetPnfOperation.getKey(getTargetEntity()), resp);
+
+        super.success(outcome);
+    }
+}
diff --git a/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/AaiGetTenantStep2.java b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/AaiGetTenantStep2.java
new file mode 100644
index 000000000..d1851dd42
--- /dev/null
+++ b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/AaiGetTenantStep2.java
@@ -0,0 +1,94 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.drools.apps.controller.usecases.step;
+
+import java.util.Collections;
+import java.util.List;
+import org.apache.commons.lang3.StringUtils;
+import org.onap.policy.common.utils.coder.StandardCoderObject;
+import org.onap.policy.controlloop.actor.aai.AaiActor;
+import org.onap.policy.controlloop.actor.aai.AaiGetTenantOperation;
+import org.onap.policy.controlloop.actorserviceprovider.OperationOutcome;
+import org.onap.policy.controlloop.actorserviceprovider.OperationProperties;
+
+/**
+ * Wrapper for {@link AaiGetTenantOperation}. The vserver name is extracted from the
+ * enrichment data and passed as the target entity for the operation. The
+ * {@link #success(OperationOutcome)} method stores the resultant "tenant" object in the
+ * step's context.
+ */
+public class AaiGetTenantStep2 extends Step2 {
+
+    private final String vserver;
+
+
+    /**
+     * Constructs the object using information from another step.
+     *
+     * @param otherStep step whose information should be used
+     */
+    public AaiGetTenantStep2(Step2 otherStep) {
+        super(otherStep, AaiActor.NAME, AaiGetTenantOperation.NAME);
+
+        vserver = event.getAai().get(VSERVER_VSERVER_NAME);
+        if (StringUtils.isBlank(vserver)) {
+            throw new IllegalArgumentException("missing " + VSERVER_VSERVER_NAME + " in enrichment data");
+        }
+    }
+
+    /**
+     * The vserver is passed as the target entity, thus we don't need to include the
+     * target entity in the property list.
+     */
+    @Override
+    public List<String> getPropertyNames() {
+        return Collections.emptyList();
+    }
+
+    @Override
+    public void setProperties() {
+        getOperation().setProperty(OperationProperties.AAI_TARGET_ENTITY, vserver);
+    }
+
+    /**
+     * Skips the operation if we already have the data.
+     */
+    @Override
+    public boolean start(long remainingMs) {
+        if (stepContext.contains(AaiGetTenantOperation.getKey(vserver))) {
+            // already have the data
+            return false;
+        }
+
+        return super.start(remainingMs);
+    }
+
+    /**
+     * Saves the response for later use.
+     */
+    @Override
+    public void success(OperationOutcome outcome) {
+        StandardCoderObject resp = outcome.getResponse();
+        stepContext.setProperty(AaiGetTenantOperation.getKey(vserver), resp);
+
+        super.success(outcome);
+    }
+}
diff --git a/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/GetTargetEntityStep2.java b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/GetTargetEntityStep2.java
new file mode 100644
index 000000000..06201b13c
--- /dev/null
+++ b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/GetTargetEntityStep2.java
@@ -0,0 +1,60 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.drools.apps.controller.usecases.step;
+
+import org.onap.policy.controlloop.actorserviceprovider.Operation;
+import org.onap.policy.drools.apps.controller.usecases.GetTargetEntityOperation2;
+import org.onap.policy.drools.apps.controller.usecases.UsecasesConstants;
+
+/**
+ * Wrapper for {@link GetTargetEntityOperation2}. The {@link #start(long)} method always
+ * returns {@code false}, as the Operation should never actually be started.
+ */
+public class GetTargetEntityStep2 extends Step2 {
+
+
+    /**
+     * Constructs the object using information from another step.
+     *
+     * @param otherStep step whose information should be used
+     */
+    public GetTargetEntityStep2(Step2 otherStep) {
+        super(otherStep, UsecasesConstants.GET_TARGET_ENTITY_ACTOR, UsecasesConstants.GET_TARGET_ENTITY_OPERATION);
+    }
+
+    @Override
+    protected Operation buildOperation() {
+        return new GetTargetEntityOperation2(stepContext, event, params);
+    }
+
+    /**
+     * The operation does not actually have to be executed, as it populates the target
+     * entity as soon as {@link Operation#setProperty(String, Object)} is invoked.
+     */
+    @Override
+    public boolean start(long remainingMs) {
+        if (!isInitialized()) {
+            throw new IllegalStateException("step has not been initialized");
+        }
+
+        return false;
+    }
+}
diff --git a/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/GuardStep2.java b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/GuardStep2.java
new file mode 100644
index 000000000..b7247ce69
--- /dev/null
+++ b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/GuardStep2.java
@@ -0,0 +1,115 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.drools.apps.controller.usecases.step;
+
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import org.onap.policy.controlloop.actor.guard.DecisionOperation;
+import org.onap.policy.controlloop.actor.guard.GuardActor;
+import org.onap.policy.controlloop.actor.so.VfModuleCreate;
+import org.onap.policy.controlloop.actorserviceprovider.Operation;
+import org.onap.policy.controlloop.actorserviceprovider.OperationProperties;
+
+/**
+ * Wrapper for a Guard operation. Note: this makes a clone of the operation parameters,
+ * replacing the payload. It overrides the operation's property names with that are
+ * relevant for guards. In addition, it overrides the relevant loadXxx() methods to load
+ * the data into the payload instead of into the operation's properties. It also
+ * increments or decrements the VF Count, depending whether the operation is a "VF Module
+ * Create" or not.
+ */
+public class GuardStep2 extends Step2 {
+    public static final String PAYLOAD_KEY_TARGET_ENTITY = "target";
+    public static final String PAYLOAD_KEY_VF_COUNT = "vfCount";
+
+    private final Operation policyOper;
+
+
+    /**
+     * Constructs the object using information from another step.
+     *
+     * @param otherStep step whose information should be used
+     */
+    public GuardStep2(Step2 otherStep, String closedLoopControlName) {
+        super(otherStep, GuardActor.NAME, DecisionOperation.NAME);
+
+        if (!otherStep.isInitialized()) {
+            throw new IllegalStateException("policy operation must be initialized before the guard operation");
+        }
+
+        this.policyOper = otherStep.getOperation();
+
+        Map<String, Object> payload = new LinkedHashMap<>();
+        payload.put("actor", otherStep.getActorName());
+        payload.put("operation", otherStep.getOperationName());
+        payload.put("requestId", params.getRequestId());
+        payload.put("clname", closedLoopControlName);
+
+        params = params.toBuilder().payload(payload).build();
+    }
+
+    @Override
+    public boolean acceptsEvent() {
+        return true;
+    }
+
+    /**
+     * Builds the list of properties on the policy's actual operation.
+     */
+    @Override
+    public List<String> getPropertyNames() {
+        List<String> names = new ArrayList<>(1);
+
+        // include VF Count if the policy's operation needs it
+        if (policyOper.getPropertyNames().contains(OperationProperties.DATA_VF_COUNT)) {
+            names.add(OperationProperties.DATA_VF_COUNT);
+        }
+
+        return names;
+    }
+
+    /**
+     * Load the target entity into the payload instead of the operation's properties.
+     */
+    @Override
+    protected void loadTargetEntity(String propName) {
+        params.getPayload().put(PAYLOAD_KEY_TARGET_ENTITY, getTargetEntity());
+    }
+
+    /**
+     * Load the VF Count into the payload instead of the operation's properties.
+     * Increments the count for "VF Module Create". Decrements it otherwise.
+     */
+    @Override
+    protected void loadVfCount(String propName) {
+        // run guard with the proposed VF count
+        int count = getVfCount();
+        if (VfModuleCreate.NAME.equals(policyOper.getName())) {
+            ++count;
+        } else {
+            --count;
+        }
+
+        params.getPayload().put(PAYLOAD_KEY_VF_COUNT, count);
+    }
+}
diff --git a/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/LockStep2.java b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/LockStep2.java
new file mode 100644
index 000000000..507a08116
--- /dev/null
+++ b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/LockStep2.java
@@ -0,0 +1,71 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.drools.apps.controller.usecases.step;
+
+import org.onap.policy.controlloop.actorserviceprovider.Operation;
+import org.onap.policy.controlloop.eventmanager.ActorConstants;
+import org.onap.policy.drools.apps.controller.usecases.LockOperation2;
+
+/**
+ * Wrapper for the LOCK pseudo operation. Arranges for the lock's future to generate an
+ * outcome.
+ */
+public class LockStep2 extends Step2 {
+
+    /**
+     * Constructs the object using information from another step.
+     *
+     * @param otherStep step whose information should be used
+     */
+    public LockStep2(Step2 otherStep) {
+        super(otherStep, ActorConstants.LOCK_ACTOR, ActorConstants.LOCK_OPERATION);
+    }
+
+    @Override
+    public boolean acceptsEvent() {
+        return true;
+    }
+
+    @Override
+    public boolean start(long remainingMs) {
+        super.start(remainingMs);
+
+        if (future != null) {
+            future.whenComplete((outcome, thrown) -> {
+                outcome.setFinalOutcome(true);
+                params.getCompleteCallback().accept(outcome);
+            });
+        }
+
+        /*
+         * ELSE: The operation must have thrown an exception. Nothing more to do as
+         * super.start() will have already propagated the exception to the completion
+         * handler.
+         */
+
+        return true;
+    }
+
+    @Override
+    protected Operation buildOperation() {
+        return new LockOperation2(stepContext, params);
+    }
+}
diff --git a/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/Step2.java b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/Step2.java
new file mode 100644
index 000000000..9275f791d
--- /dev/null
+++ b/controlloop/common/controller-usecases/src/main/java/org/onap/policy/drools/apps/controller/usecases/step/Step2.java
@@ -0,0 +1,433 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.drools.apps.controller.usecases.step;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+import lombok.Getter;
+import lombok.Setter;
+import org.apache.commons.lang3.StringUtils;
+import org.onap.aai.domain.yang.CloudRegion;
+import org.onap.aai.domain.yang.GenericVnf;
+import org.onap.aai.domain.yang.ModelVer;
+import org.onap.aai.domain.yang.ServiceInstance;
+import org.onap.aai.domain.yang.Tenant;
+import org.onap.policy.aai.AaiCqResponse;
+import org.onap.policy.common.utils.coder.StandardCoderObject;
+import org.onap.policy.controlloop.VirtualControlLoopEvent;
+import org.onap.policy.controlloop.actor.aai.AaiGetPnfOperation;
+import org.onap.policy.controlloop.actor.aai.AaiGetTenantOperation;
+import org.onap.policy.controlloop.actorserviceprovider.OperationOutcome;
+import org.onap.policy.controlloop.actorserviceprovider.OperationProperties;
+import org.onap.policy.controlloop.actorserviceprovider.parameters.ControlLoopOperationParams;
+import org.onap.policy.controlloop.eventmanager.Step;
+import org.onap.policy.controlloop.eventmanager.StepContext;
+import org.onap.policy.drools.apps.controller.usecases.UsecasesConstants;
+
+/**
+ * Steps specific to the usecases controller. The {@link #setProperties()} method is used
+ * to load the various properties into the operation, extracting enrichment data where
+ * appropriate, and extracting other data from the step's context. For each property,
+ * there is a getXxx() method for extracting the value and a loadXxx() method for loading
+ * the extracted value into the operation. In addition, the
+ * {@link #success(OperationOutcome)} method is responsible for extracting responses from
+ * an operation outcome and recording the data in the step's context for use by subsequent
+ * steps.
+ */
+public class Step2 extends Step {
+    public static final String TARGET_INFO_MSG = "Target information";
+    public static final String ENRICHMENT_PREFIX = "enrichment/";
+    public static final String VSERVER_VSERVER_NAME = "vserver.vserver-name";
+    public static final String RESOURCE_LINK = "resource-link";
+    public static final String RESULT_DATA = "result-data";
+
+    private static final Map<String, BiConsumer<Step2, String>> PROPERTY_LOADER;
+    private static final Map<String, Consumer<Step2>> PROPERTY_SAVER;
+
+    static {
+        /*
+         * Populate map for PROPERTY_LOADER.
+         */
+        Map<String, BiConsumer<Step2, String>> map = new HashMap<>();
+
+        map.put(OperationProperties.AAI_DEFAULT_CLOUD_REGION, Step2::loadCloudRegion);
+        map.put(OperationProperties.AAI_DEFAULT_TENANT, Step2::loadTenant);
+        map.put(OperationProperties.AAI_PNF, Step2::loadPnf);
+        map.put(OperationProperties.AAI_RESOURCE_VNF, Step2::loadResourceVnf);
+        map.put(OperationProperties.AAI_SERVICE, Step2::loadService);
+        map.put(OperationProperties.AAI_SERVICE_MODEL, Step2::loadServiceModel);
+        map.put(OperationProperties.AAI_TARGET_ENTITY, Step2::loadTargetEntity);
+        map.put(OperationProperties.AAI_VNF, Step2::loadVnf);
+        map.put(OperationProperties.AAI_VNF_MODEL, Step2::loadVnfModel);
+        map.put(OperationProperties.AAI_VSERVER_LINK, Step2::loadVserverLink);
+        map.put(OperationProperties.DATA_VF_COUNT, Step2::loadVfCount);
+        map.put(OperationProperties.EVENT_ADDITIONAL_PARAMS, Step2::loadAdditionalEventParams);
+        map.put(OperationProperties.EVENT_PAYLOAD, Step2::loadEventPayload);
+        map.put(OperationProperties.OPT_CDS_GRPC_AAI_PROPERTIES, Step2::loadOptCdsGrpcAaiProperties);
+
+        map.put(UsecasesConstants.AAI_DEFAULT_GENERIC_VNF, Step2::loadDefaultGenericVnf);
+
+        PROPERTY_LOADER = Collections.unmodifiableMap(map);
+
+
+        /*
+         * Populate map for PROPERTY_SAVER.
+         */
+        Map<String, Consumer<Step2>> map2 = new HashMap<>();
+
+        map2.put(OperationProperties.DATA_VF_COUNT, Step2::storeVfCount);
+
+        PROPERTY_SAVER = Collections.unmodifiableMap(map2);
+    }
+
+
+    protected final StepContext stepContext;
+    protected final VirtualControlLoopEvent event;
+
+    /**
+     * {@code True} if the associated preprocessing steps have been loaded, {@code false}
+     * otherwise.
+     */
+    @Getter
+    @Setter
+    private boolean preprocessed;
+
+    /**
+     * Actions to take to store the Operation's properties back into the context.
+     */
+    private List<Consumer<Step2>> postProcessors = new LinkedList<>();
+
+
+    /**
+     * Constructs the object. This is used when constructing the step for the policy's
+     * actual operation.
+     *
+     * @param stepContext the step's context
+     * @param params operation parameters
+     * @param event the event being processed
+     */
+    public Step2(StepContext stepContext, ControlLoopOperationParams params, VirtualControlLoopEvent event) {
+        super(params, new AtomicReference<>());
+        this.stepContext = stepContext;
+        this.event = event;
+    }
+
+    /**
+     * Constructs the object using information from another step. This is used when
+     * constructing a preprocessing step.
+     *
+     * @param otherStep step whose information should be used
+     * @param actor actor name
+     * @param operation operation name
+     */
+    public Step2(Step2 otherStep, String actor, String operation) {
+        super(otherStep, actor, operation);
+        this.stepContext = otherStep.stepContext;
+        this.event = otherStep.event;
+    }
+
+    /**
+     * Determines if starting this step indicates acceptance of the event. The default
+     * method simply invokes {@link #isPolicyStep()}.
+     *
+     * @return {@code true} if this step accepts the event, {@code false} if it is still
+     *         indeterminate
+     */
+    public boolean acceptsEvent() {
+        return isPolicyStep();
+    }
+
+    /**
+     * Indicates that the step succeeded with the given outcome. Invoked by the rules. The
+     * default method invokes the post processors.
+     *
+     * @param outcome operation's outcome
+     */
+    public void success(OperationOutcome outcome) {
+        for (Consumer<Step2> proc : postProcessors) {
+            proc.accept(this);
+        }
+    }
+
+    /**
+     * Gets the names of the properties required by the operation. The default method just
+     * delegates to the operation to identify the properties.
+     *
+     * @return the names of the properties required by the operation
+     */
+    public List<String> getPropertyNames() {
+        return getOperation().getPropertyNames();
+    }
+
+    /**
+     * Sets the operation's properties. This is invoked <i>after</i> any preprocessor
+     * steps have been performed. It also adds items to {@link #postProcessors}.
+     */
+    public void setProperties() {
+        postProcessors.clear();
+
+        for (String propName : getPropertyNames()) {
+            // identify the saver, if any
+            Consumer<Step2> saver = PROPERTY_SAVER.get(propName);
+            if (saver != null) {
+                postProcessors.add(saver);
+            }
+
+
+            // load data
+            if (propName.startsWith(ENRICHMENT_PREFIX)) {
+                loadEnrichment(propName);
+                continue;
+            }
+
+            BiConsumer<Step2, String> loader = PROPERTY_LOADER.get(propName);
+            if (loader == null) {
+                throw new IllegalArgumentException("unknown property " + propName + " needed by " + getActorName() + "."
+                                + getOperationName());
+            }
+
+            loader.accept(this, propName);
+        }
+    }
+
+    protected void loadCloudRegion(String propName) {
+        getOperation().setProperty(propName, getCloudRegion());
+    }
+
+    protected void loadTenant(String propName) {
+        getOperation().setProperty(propName, getTenant());
+    }
+
+    protected void loadPnf(String propName) {
+        getOperation().setProperty(propName, getPnf());
+    }
+
+    protected void loadResourceVnf(String propName) {
+        getOperation().setProperty(propName, getResourceVnf());
+    }
+
+    protected void loadService(String propName) {
+        getOperation().setProperty(propName, getService());
+    }
+
+    protected void loadServiceModel(String propName) {
+        getOperation().setProperty(propName, getServiceModel());
+    }
+
+    protected void loadTargetEntity(String propName) {
+        getOperation().setProperty(propName, getTargetEntity());
+    }
+
+    protected void loadVnf(String propName) {
+        getOperation().setProperty(propName, getVnf());
+    }
+
+    protected void loadVnfModel(String propName) {
+        getOperation().setProperty(propName, getVnfModel());
+    }
+
+    protected void loadVserverLink(String propName) {
+        getOperation().setProperty(propName, getVserverLink());
+    }
+
+    protected void loadVfCount(String propName) {
+        getOperation().setProperty(propName, getVfCount());
+    }
+
+    protected void loadEnrichment(String propName) {
+        getOperation().setProperty(propName, getEnrichment(propName));
+    }
+
+    protected void loadAdditionalEventParams(String propName) {
+        getOperation().setProperty(propName, getAdditionalEventParams());
+    }
+
+    protected void loadEventPayload(String propName) {
+        getOperation().setProperty(propName, getEventPayload());
+    }
+
+    protected void loadOptCdsGrpcAaiProperties(String propName) {
+        // do nothing
+    }
+
+    protected void loadDefaultGenericVnf(String propName) {
+        getOperation().setProperty(propName, getDefaultGenericVnf());
+    }
+
+    protected CloudRegion getCloudRegion() {
+        AaiCqResponse aaicq = getCustomQueryData();
+        return aaicq.getDefaultCloudRegion();
+    }
+
+    protected Tenant getTenant() {
+        AaiCqResponse aaicq = getCustomQueryData();
+        return aaicq.getDefaultTenant();
+    }
+
+    protected StandardCoderObject getPnf() {
+        return stepContext.getProperty(AaiGetPnfOperation.getKey(getTargetEntity()));
+    }
+
+    protected GenericVnf getResourceVnf() {
+        verifyNotNull(TARGET_INFO_MSG, params.getTarget());
+
+        String resourceId = params.getTarget().getResourceID();
+
+        verifyNotNull("Target resource ID", resourceId);
+
+        AaiCqResponse aaicq = getCustomQueryData();
+        return aaicq.getGenericVnfByModelInvariantId(resourceId);
+    }
+
+    protected ServiceInstance getService() {
+        AaiCqResponse aaicq = getCustomQueryData();
+        return aaicq.getServiceInstance();
+    }
+
+    protected ModelVer getServiceModel() {
+        AaiCqResponse aaicq = getCustomQueryData();
+        ServiceInstance service = aaicq.getServiceInstance();
+        return aaicq.getModelVerByVersionId(service.getModelVersionId());
+    }
+
+    /**
+     * The default method assumes there is only one target entity and that it's stored
+     * within the step's context.
+     */
+    protected String getTargetEntity() {
+        return stepContext.getProperty(OperationProperties.AAI_TARGET_ENTITY);
+    }
+
+    protected GenericVnf getVnf() {
+        verifyNotNull(TARGET_INFO_MSG, params.getTarget());
+
+        String modelInvariantId = params.getTarget().getModelInvariantId();
+
+        verifyNotNull("modelInvariantId", modelInvariantId);
+
+        AaiCqResponse aaicq = getCustomQueryData();
+        return aaicq.getGenericVnfByVfModuleModelInvariantId(modelInvariantId);
+    }
+
+    protected ModelVer getVnfModel() {
+        GenericVnf vnf = getVnf();
+        AaiCqResponse aaicq = getCustomQueryData();
+        return aaicq.getModelVerByVersionId(vnf.getModelVersionId());
+    }
+
+    protected String getVserverLink() {
+        String vserver = event.getAai().get(VSERVER_VSERVER_NAME);
+        if (StringUtils.isBlank(vserver)) {
+            throw new IllegalArgumentException("missing " + VSERVER_VSERVER_NAME + " in enrichment data");
+        }
+
+        StandardCoderObject tenant = stepContext.getProperty(AaiGetTenantOperation.getKey(vserver));
+        verifyNotNull("tenant data", tenant);
+
+        String resourceLink = tenant.getString(RESULT_DATA, 0, RESOURCE_LINK);
+        verifyNotNull("tenant data resource-link", resourceLink);
+
+        return stripPrefix(resourceLink, 3);
+    }
+
+    protected Integer getVfCount() {
+        if (stepContext.contains(OperationProperties.DATA_VF_COUNT)) {
+            return stepContext.getProperty(OperationProperties.DATA_VF_COUNT);
+        }
+
+        verifyNotNull(TARGET_INFO_MSG, params.getTarget());
+
+        String modelCustomizationId = params.getTarget().getModelCustomizationId();
+        String modelInvariantId = params.getTarget().getModelInvariantId();
+        String modelVersionId = params.getTarget().getModelVersionId();
+
+        verifyNotNull("target modelCustomizationId", modelCustomizationId);
+        verifyNotNull("target modelInvariantId", modelInvariantId);
+        verifyNotNull("target modelVersionId", modelVersionId);
+
+        AaiCqResponse aaicq = getCustomQueryData();
+        return aaicq.getVfModuleCount(modelCustomizationId, modelInvariantId, modelVersionId);
+    }
+
+    protected String getEnrichment(String propName) {
+        String enrichmentKey = propName.substring(ENRICHMENT_PREFIX.length());
+        String value = event.getAai().get(enrichmentKey);
+        verifyNotNull(propName, value);
+
+        return value;
+    }
+
+    protected Map<String, String> getAdditionalEventParams() {
+        return event.getAdditionalEventParams();
+    }
+
+    protected String getEventPayload() {
+        return event.getPayload();
+    }
+
+    protected GenericVnf getDefaultGenericVnf() {
+        AaiCqResponse aaicq = getCustomQueryData();
+        return aaicq.getDefaultGenericVnf();
+    }
+
+    protected AaiCqResponse getCustomQueryData() {
+        AaiCqResponse aaicq = stepContext.getProperty(AaiCqResponse.CONTEXT_KEY);
+        verifyNotNull("custom query data", aaicq);
+
+        return aaicq;
+    }
+
+    protected void storeVfCount() {
+        if (!getOperation().containsProperty(OperationProperties.DATA_VF_COUNT)) {
+            return;
+        }
+
+        int vfcount = getOperation().getProperty(OperationProperties.DATA_VF_COUNT);
+        stepContext.setProperty(OperationProperties.DATA_VF_COUNT, vfcount);
+    }
+
+    protected void verifyNotNull(String propName, Object value) {
+        if (value == null) {
+            throw new IllegalArgumentException(
+                            "missing " + propName + " for " + getActorName() + "." + getOperationName());
+        }
+    }
+
+    protected static String stripPrefix(String resourceLink, int ncomponents) {
+        int previdx = -1;
+        for (int nslashes = 0; nslashes < ncomponents; ++nslashes) {
+            int idx = resourceLink.indexOf('/', previdx + 1);
+            if (idx < 0) {
+                break;
+            }
+
+            previdx = idx;
+        }
+
+        return resourceLink.substring(Math.max(0, previdx));
+    }
+}