Adding policy-model, model-api & engine-model

Change-Id: I56702b8f0953457d493f894d155b2a6ddc87b10c
Issue-ID: POLICY-856
Signed-off-by: waqas.ikram <waqas.ikram@ericsson.com>

4 files changed, 1020 insertions, 0 deletions

diff --git a/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/AxEngineModel.java b/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/AxEngineModel.java
new file mode 100644
index 000000000..b7733c6a3
--- /dev/null
+++ b/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/AxEngineModel.java
@@ -0,0 +1,395 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. 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.
+ * 
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.apex.model.enginemodel.concepts;
+
+import java.text.SimpleDateFormat;
+import java.util.List;
+
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.Enumerated;
+import javax.persistence.JoinColumn;
+import javax.persistence.JoinColumns;
+import javax.persistence.Table;
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlElement;
+import javax.xml.bind.annotation.XmlRootElement;
+import javax.xml.bind.annotation.XmlType;
+
+import org.onap.policy.apex.model.basicmodel.concepts.AxArtifactKey;
+import org.onap.policy.apex.model.basicmodel.concepts.AxConcept;
+import org.onap.policy.apex.model.basicmodel.concepts.AxKey;
+import org.onap.policy.apex.model.basicmodel.concepts.AxKeyInformation;
+import org.onap.policy.apex.model.basicmodel.concepts.AxReferenceKey;
+import org.onap.policy.apex.model.basicmodel.concepts.AxValidationMessage;
+import org.onap.policy.apex.model.basicmodel.concepts.AxValidationResult;
+import org.onap.policy.apex.model.basicmodel.concepts.AxValidationResult.ValidationResult;
+import org.onap.policy.apex.model.contextmodel.concepts.AxContextAlbums;
+import org.onap.policy.apex.model.contextmodel.concepts.AxContextModel;
+import org.onap.policy.apex.model.contextmodel.concepts.AxContextSchemas;
+import org.onap.policy.apex.model.utilities.Assertions;
+
+/**
+ * A container class for an Apex engine model. This class is a container class that allows an Apex
+ * model to be constructed that contains the current context {@link AxContextModel}, current state
+ * {@link AxEngineState} and current statistics {@link AxEngineStats} of an Apex engine. This model
+ * is used by an Apex engine to pass its current execution state to any system that wishes to query
+ * that information. The time stamp of the engine model is the time at which the state and
+ * statistics of the engine were read.
+ * <p>
+ * Validation checks that the current state {@link AxEngineState} is defined and that the time stamp
+ * is set on the engine model.
+ */
+@Entity
+@Table(name = "AxEngineModel")
+@XmlRootElement(name = "apexEngineModel", namespace = "http://www.onap.org/policy/apex-pdp")
+@XmlAccessorType(XmlAccessType.FIELD)
+@XmlType(name = "AxEngineModel", namespace = "http://www.onap.org/policy/apex-pdp",
+        propOrder = {"timestamp", "state", "stats"})
+
+public class AxEngineModel extends AxContextModel {
+    private static final long serialVersionUID = 6381235864606564046L;
+    private static final int HASH_CODE_PRIME = 32;
+
+    @Column(name = "timestamp")
+    private long timestamp;
+
+    @Enumerated
+    @Column(name = "state")
+    @XmlElement(required = true)
+    private AxEngineState state;
+
+    // @formatter:off
+    @JoinColumns({
+            @JoinColumn(name = "statsParentKeyName", referencedColumnName = "parentKeyName", updatable = false,
+                    insertable = false),
+            @JoinColumn(name = "statsParentKeyVersion", referencedColumnName = "parentKeyVersion", updatable = false,
+                    insertable = false),
+            @JoinColumn(name = "statsParentLocalName ", referencedColumnName = "parentLocalName", updatable = false,
+                    insertable = false),
+            @JoinColumn(name = "statsLocalName", referencedColumnName = "localName", updatable = false,
+                    insertable = false)})
+    private AxEngineStats stats;
+    // @formatter:on
+
+    /**
+     * The Default Constructor creates an engine model with a null key and all its fields undefined.
+     */
+    public AxEngineModel() {
+        this(new AxArtifactKey());
+        timestamp = -1;
+    }
+
+    /**
+     * Copy constructor
+     * 
+     * @param copyConcept the concept to copy from
+     */
+    public AxEngineModel(final AxEngineModel copyConcept) {
+        super(copyConcept);
+    }
+
+    /**
+     * The Keyed Constructor creates an engine model with the given key and all its fields
+     * undefined.
+     *
+     * @param key the engine model key
+     */
+    public AxEngineModel(final AxArtifactKey key) {
+        this(key, new AxContextSchemas(new AxArtifactKey(key.getName() + "_DataTypes", key.getVersion())),
+                new AxKeyInformation(new AxArtifactKey(key.getName() + "_KeyInfo", key.getVersion())),
+                new AxContextAlbums(new AxArtifactKey(key.getName() + "_Context", key.getVersion())));
+    }
+
+    /**
+     * This Constructor creates an engine model with its context model data types all defined, the
+     * state of the engine model is undefined.
+     *
+     * @param key the engine model key
+     * @param contextSchemas the context schemas used by the engine model
+     * @param keyInformation the key information used by the engine model
+     * @param contextAlbums the context albums used by the engine model
+     */
+    public AxEngineModel(final AxArtifactKey key, final AxContextSchemas contextSchemas,
+            final AxKeyInformation keyInformation, final AxContextAlbums contextAlbums) {
+        this(key, contextSchemas, keyInformation, contextAlbums, AxEngineState.UNDEFINED,
+                new AxEngineStats(new AxReferenceKey(key, "_EngineStats", key.getVersion())));
+    }
+
+    /**
+     * This Constructor creates an engine model with all its fields defined.
+     *
+     * @param key the engine model key
+     * @param contextSchemas the context schemas used by the engine model
+     * @param keyInformation the key information used by the engine model
+     * @param contextAlbums the context albums used by the engine model
+     * @param state the state of the engine in the engine model
+     * @param stats the statistics of the engine in the engine model
+     */
+    public AxEngineModel(final AxArtifactKey key, final AxContextSchemas contextSchemas,
+            final AxKeyInformation keyInformation, final AxContextAlbums contextAlbums, final AxEngineState state,
+            final AxEngineStats stats) {
+        super(key, contextSchemas, contextAlbums, keyInformation);
+        Assertions.argumentNotNull(state, "state may not be null");
+        Assertions.argumentNotNull(stats, "stats may not be null");
+
+        this.state = state;
+        this.stats = stats;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.contextmodel.concepts.AxContextModel#getKeys()
+     */
+    @Override
+    public List<AxKey> getKeys() {
+        final List<AxKey> keyList = super.getKeys();
+        keyList.addAll(stats.getKeys());
+        return keyList;
+    }
+
+    /**
+     * Gets the time stamp at which the engine model measurements were taken.
+     *
+     * @return the time stamp at which the engine model measurements were taken
+     */
+    public long getTimestamp() {
+        return timestamp;
+    }
+
+    /**
+     * Gets the time stamp at which the engine model measurements were taken as a string.
+     *
+     * @return the time stamp string
+     */
+    public String getTimeStampString() {
+        return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").format(timestamp);
+    }
+
+    /**
+     * Sets the time stamp at which the engine model measurements were taken.
+     *
+     * @param timestamp the time stamp at which the engine model measurements were taken
+     */
+    public void setTimestamp(final long timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    /**
+     * Gets the state of the engine at the time the measurements were taken.
+     *
+     * @return the state of the engine at the time the measurements were taken
+     */
+    public AxEngineState getState() {
+        return state;
+    }
+
+    /**
+     * Sets the state of the engine.
+     *
+     * @param state the state of the engine
+     */
+    public void setState(final AxEngineState state) {
+        Assertions.argumentNotNull(state, "state may not be null");
+        this.state = state;
+    }
+
+    /**
+     * Gets the statistics of the engine at the time the measurements were taken.
+     *
+     * @return the statistics of the engine at the time the measurements were taken
+     */
+    public AxEngineStats getStats() {
+        return stats;
+    }
+
+    /**
+     * Sets the the statistics of the engine.
+     *
+     * @param stats the the statistics of the engine
+     */
+    public void setStats(final AxEngineStats stats) {
+        Assertions.argumentNotNull(stats, "stats may not be null");
+        this.stats = stats;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see
+     * org.onap.policy.apex.model.contextmodel.concepts.AxContextModel#validate(org.onap.policy.apex
+     * .model .basicmodel.concepts.AxValidationResult)
+     */
+    @Override
+    public AxValidationResult validate(final AxValidationResult resultIn) {
+        AxValidationResult result = resultIn;
+
+        result = stats.validate(result);
+
+        if (timestamp == -1) {
+            result.addValidationMessage(new AxValidationMessage(getKey(), this.getClass(), ValidationResult.INVALID,
+                    this.getClass().getSimpleName() + " - timestamp is not set"));
+        }
+
+        if (state == AxEngineState.UNDEFINED) {
+            result.addValidationMessage(new AxValidationMessage(getKey(), this.getClass(), ValidationResult.INVALID,
+                    this.getClass().getSimpleName() + " - state is UNDEFINED"));
+        }
+
+        return result;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.contextmodel.concepts.AxContextModel#clean()
+     */
+    @Override
+    public void clean() {
+        super.clean();
+        stats.clean();
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.contextmodel.concepts.AxContextModel#toString()
+     */
+    @Override
+    public String toString() {
+        final StringBuilder builder = new StringBuilder();
+        builder.append(this.getClass().getSimpleName());
+        builder.append(":(");
+        builder.append(super.toString());
+        builder.append(",timestamp=");
+        builder.append(timestamp);
+        builder.append(",state=");
+        builder.append(state);
+        builder.append(",stats=");
+        builder.append(stats);
+        builder.append(")");
+        return builder.toString();
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see
+     * org.onap.policy.apex.model.basicmodel.concepts.AxConcept#copyTo(org.onap.policy.apex.model.
+     * basicmodel.concepts.AxConcept)
+     */
+    @Override
+    public AxConcept copyTo(final AxConcept targetObject) {
+        Assertions.argumentNotNull(targetObject, "target may not be null");
+
+        final Object copyObject = targetObject;
+        Assertions.instanceOf(copyObject, AxEngineModel.class);
+
+        final AxEngineModel copy = ((AxEngineModel) copyObject);
+        super.copyTo(targetObject);
+        copy.timestamp = timestamp;
+        copy.setState(state);
+        copy.setStats(new AxEngineStats(stats));
+
+        return copy;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.contextmodel.concepts.AxContextModel#hashCode()
+     */
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + super.hashCode();
+        result = prime * result + (int) (timestamp ^ (timestamp >>> HASH_CODE_PRIME));
+        result = prime * result + state.hashCode();
+        result = prime * result + stats.hashCode();
+        return result;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.contextmodel.concepts.AxContextModel#equals(java.lang.Object)
+     */
+    @Override
+    public boolean equals(final Object obj) {
+        if (obj == null) {
+            throw new IllegalArgumentException("comparison object may not be null");
+        }
+
+        if (this == obj) {
+            return true;
+        }
+
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+
+        final AxEngineModel other = (AxEngineModel) obj;
+        if (!super.equals(other)) {
+            return false;
+        }
+        if (timestamp != other.timestamp) {
+            return false;
+        }
+        if (!state.equals(other.state)) {
+            return false;
+        }
+        return stats.equals(other.stats);
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see
+     * org.onap.policy.apex.model.contextmodel.concepts.AxContextModel#compareTo(org.onap.policy.
+     * apex.model.basicmodel.concepts.AxConcept)
+     */
+    @Override
+    public int compareTo(final AxConcept otherObj) {
+        Assertions.argumentNotNull(otherObj, "comparison object may not be null");
+
+        if (this == otherObj) {
+            return 0;
+        }
+        if (getClass() != otherObj.getClass()) {
+            return this.hashCode() - otherObj.hashCode();
+        }
+
+        final AxEngineModel other = (AxEngineModel) otherObj;
+        if (!super.equals(other)) {
+            return super.compareTo(other);
+        }
+        if (timestamp != other.timestamp) {
+            return (int) (timestamp - other.timestamp);
+        }
+        if (!state.equals(other.state)) {
+            return state.compareTo(other.state);
+        }
+        return stats.compareTo(other.stats);
+    }
+}
diff --git a/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/AxEngineState.java b/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/AxEngineState.java
new file mode 100644
index 000000000..f77fe1910
--- /dev/null
+++ b/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/AxEngineState.java
@@ -0,0 +1,46 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. 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.
+ * 
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.apex.model.enginemodel.concepts;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlType;
+
+/**
+ * This enumeration indicates the execution state of an Apex engine.
+ *
+ * @author Liam Fallon (liam.fallon@ericsson.com)
+ */
+
+@XmlAccessorType(XmlAccessType.FIELD)
+@XmlType(name = "AxEngineState", namespace = "http://www.onap.org/policy/apex-pdp")
+public enum AxEngineState {
+    /** The state of the engine is not known. */
+    UNDEFINED,
+    /** The engine is stopped. */
+    STOPPED,
+    /** The engine is running and is waiting to execute a policy. */
+    READY,
+    /** The engine is running and is executing a policy. */
+    EXECUTING,
+    /** The engine has been ordered to stop and is stoping. */
+    STOPPING;
+}
diff --git a/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/AxEngineStats.java b/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/AxEngineStats.java
new file mode 100644
index 000000000..b7593e751
--- /dev/null
+++ b/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/AxEngineStats.java
@@ -0,0 +1,545 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. 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.
+ * 
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.apex.model.enginemodel.concepts;
+
+import java.text.SimpleDateFormat;
+import java.util.List;
+
+import javax.persistence.Column;
+import javax.persistence.EmbeddedId;
+import javax.persistence.Entity;
+import javax.persistence.Table;
+import javax.persistence.Transient;
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlElement;
+import javax.xml.bind.annotation.XmlRootElement;
+import javax.xml.bind.annotation.XmlType;
+
+import org.onap.policy.apex.model.basicmodel.concepts.AxArtifactKey;
+import org.onap.policy.apex.model.basicmodel.concepts.AxConcept;
+import org.onap.policy.apex.model.basicmodel.concepts.AxKey;
+import org.onap.policy.apex.model.basicmodel.concepts.AxReferenceKey;
+import org.onap.policy.apex.model.basicmodel.concepts.AxValidationMessage;
+import org.onap.policy.apex.model.basicmodel.concepts.AxValidationResult;
+import org.onap.policy.apex.model.basicmodel.concepts.AxValidationResult.ValidationResult;
+import org.onap.policy.apex.model.utilities.Assertions;
+
+/**
+ * This class is a java bean that is used to record statistics on Apex engines as they execute.
+ * Statistics on the number of events, the amount of time taken to execute the last policy, the
+ * average policy execution time, the up time of the engine, and the time stamp of the last engine
+ * start are recorded.
+ */
+
+@Entity
+@Table(name = "AxEngineStats")
+
+@XmlAccessorType(XmlAccessType.FIELD)
+@XmlRootElement(name = "apexEngineStats", namespace = "http://www.onap.org/policy/apex-pdp")
+@XmlType(name = "AxEngineStats", namespace = "http://www.onap.org/policy/apex-pdp", propOrder = {"key", "timeStamp",
+        "eventCount", "lastExecutionTime", "averageExecutionTime", "upTime", "lastStart"})
+public class AxEngineStats extends AxConcept {
+    private static final long serialVersionUID = -6981129081962785368L;
+    private static final int HASH_CODE_PRIME = 32;
+
+    @EmbeddedId
+    @XmlElement(name = "key", required = true)
+    private AxReferenceKey key;
+
+    @Column
+    @XmlElement(required = true)
+    private long timeStamp;
+
+    @Column
+    @XmlElement(required = true)
+    private long eventCount;
+
+    @Column
+    @XmlElement(required = true)
+    private long lastExecutionTime;
+
+    @Column
+    @XmlElement(required = true)
+    private double averageExecutionTime;
+
+    @Column
+    @XmlElement(required = true)
+    private long upTime;
+
+    @Transient
+    private transient long lastEnterTime;
+
+    @Column
+    @XmlElement(required = true)
+    private long lastStart;
+
+    /**
+     * The Default Constructor creates an engine statistics instance with a null key and with all
+     * values cleared.
+     */
+    public AxEngineStats() {
+        this(new AxReferenceKey());
+        timeStamp = 0;
+        eventCount = 0;
+        lastExecutionTime = 0;
+        averageExecutionTime = 0;
+        upTime = 0;
+        lastEnterTime = 0;
+        lastStart = 0;
+    }
+
+    /**
+     * Copy constructor
+     * 
+     * @param copyConcept the concept to copy from
+     */
+    public AxEngineStats(final AxEngineStats copyConcept) {
+        super(copyConcept);
+    }
+
+    /**
+     * The Keyed Constructor creates an engine statistics instance with the given key and all values
+     * cleared.
+     *
+     * @param key the key
+     */
+    public AxEngineStats(final AxReferenceKey key) {
+        this(key, 0, 0, 0, 0, 0, 0);
+    }
+
+    /**
+     * This Constructor creates an engine statistics instance with all its fields set.
+     *
+     * @param key the engine statistics key
+     * @param timeStamp the time stamp at which the statistics were recorded
+     * @param eventCount the number of events processed by the engine
+     * @param lastExecutionTime the amount of time taken to execute the last policy
+     * @param averageExecutionTime the average amount of time taken to execute a policy
+     * @param upTime the time that has elapsed since the policy engine was started
+     * @param lastStart the time at which the policy engine was last started
+     */
+    public AxEngineStats(final AxReferenceKey key, final long timeStamp, final long eventCount,
+            final long lastExecutionTime, final double averageExecutionTime, final long upTime, final long lastStart) {
+        super();
+        Assertions.argumentNotNull(key, "key may not be null");
+
+        this.key = key;
+        this.timeStamp = timeStamp;
+        this.eventCount = eventCount;
+        this.lastExecutionTime = lastExecutionTime;
+        this.averageExecutionTime = averageExecutionTime;
+        this.upTime = upTime;
+        this.lastStart = lastStart;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.basicmodel.concepts.AxConcept#getKey()
+     */
+    @Override
+    public AxReferenceKey getKey() {
+        return key;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.basicmodel.concepts.AxConcept#getKeys()
+     */
+    @Override
+    public List<AxKey> getKeys() {
+        return key.getKeys();
+    }
+
+    /**
+     * Sets the engine statistics key.
+     *
+     * @param key the engine statistics key
+     */
+    public void setKey(final AxReferenceKey key) {
+        Assertions.argumentNotNull(key, "key may not be null");
+        this.key = key;
+    }
+
+    /**
+     * Gets the time stamp at which the statistics were recorded.
+     *
+     * @return the time stamp at which the statistics were recorded
+     */
+    public long getTimeStamp() {
+        return timeStamp;
+    }
+
+    /**
+     * Gets the time stamp at which the statistics were recorded as a string.
+     *
+     * @return the time stamp at which the statistics were recorded as a string
+     */
+    public String getTimeStampString() {
+        return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").format(timeStamp);
+    }
+
+    /**
+     * Sets the time stamp at which the statistics were recorded.
+     *
+     * @param timeStamp the time stamp at which the statistics were recorded
+     */
+    public void setTimeStamp(final long timeStamp) {
+        this.timeStamp = timeStamp;
+    }
+
+    /**
+     * Gets the number of events processed by the engine.
+     *
+     * @return the number of events processed by the engine
+     */
+    public long getEventCount() {
+        return eventCount;
+    }
+
+    /**
+     * Sets the number of events processed by the engine.
+     *
+     * @param eventCount the number of events processed by the engine
+     */
+    public void setEventCount(final long eventCount) {
+        this.eventCount = eventCount;
+    }
+
+    /**
+     * Gets the amount of time taken to execute the last policy.
+     *
+     * @return the amount of time taken to execute the last policy
+     */
+    public long getLastExecutionTime() {
+        return lastExecutionTime;
+    }
+
+    /**
+     * Sets the amount of time taken to execute the last policy.
+     *
+     * @param lastExecutionTime the amount of time taken to execute the last policy
+     */
+    public void setLastExecutionTime(final long lastExecutionTime) {
+        this.lastExecutionTime = lastExecutionTime;
+    }
+
+    /**
+     * Gets the average amount of time taken to execute a policy.
+     *
+     * @return the average amount of time taken to execute a policy
+     */
+    public double getAverageExecutionTime() {
+        return averageExecutionTime;
+    }
+
+    /**
+     * Sets the average amount of time taken to execute a policy.
+     *
+     * @param averageExecutionTime the average amount of time taken to execute a policy
+     */
+    public void setAverageExecutionTime(final double averageExecutionTime) {
+        this.averageExecutionTime = averageExecutionTime;
+    }
+
+    /**
+     * Gets the time that has elapsed since the policy engine was started.
+     *
+     * @return the time that has elapsed since the policy engine was started
+     */
+    public long getUpTime() {
+        if (this.getLastStart() != 0) {
+            return upTime + (timeStamp - this.getLastStart());
+        }
+        return upTime;
+    }
+
+    /**
+     * Sets the time that has elapsed since the policy engine was started.
+     *
+     * @param upTime the time that has elapsed since the policy engine was started
+     */
+    public void setUpTime(final long upTime) {
+        this.upTime = upTime;
+    }
+
+    /**
+     * Sets the time at which the policy engine was last started.
+     *
+     * @param lastStart the time at which the policy engine was last started
+     */
+    private void setLastStart(final long lastStart) {
+        this.lastStart = lastStart;
+    }
+
+    /**
+     * Gets the time at which the policy engine was last started.
+     *
+     * @return the time at which the policy engine was last started
+     */
+    private long getLastStart() {
+        return lastStart;
+    }
+
+    /**
+     * Resets all the statistic values to zero.
+     */
+    public synchronized void reset() {
+        timeStamp = 0;
+        eventCount = 0;
+        lastExecutionTime = 0;
+        averageExecutionTime = 0;
+        upTime = 0;
+        lastEnterTime = 0;
+        lastStart = 0;
+    }
+
+    /**
+     * Updates the statistics when called, used by the Apex engine when it starts executing a
+     * policy.
+     *
+     * @param eventkey the key of the event that is being executed
+     */
+    public synchronized void executionEnter(final AxArtifactKey eventkey) {
+        final long now = System.currentTimeMillis();
+        eventCount++;
+        if (eventCount < 0) {
+            eventCount = 2;
+        }
+        lastEnterTime = now;
+        timeStamp = now;
+    }
+
+    /**
+     * Updates the statistics when called, used by the Apex engine when it completes executing a
+     * policy.
+     */
+    public synchronized void executionExit() {
+        final long now = System.currentTimeMillis();
+        lastExecutionTime = now - lastEnterTime;
+
+        averageExecutionTime = ((averageExecutionTime * (eventCount - 1.0)) + lastExecutionTime) / eventCount;
+        lastEnterTime = 0;
+        timeStamp = System.currentTimeMillis();
+    }
+
+    /**
+     * Updates the statistics when called, used by the Apex engine when it is started.
+     */
+    public synchronized void engineStart() {
+        final long now = System.currentTimeMillis();
+        timeStamp = now;
+        this.setLastStart(now);
+    }
+
+    /**
+     * Updates the statistics when called, used by the Apex engine when it is stopped.
+     */
+    public synchronized void engineStop() {
+        final long now = System.currentTimeMillis();
+        timeStamp = now;
+        upTime += (timeStamp - this.getLastStart());
+        this.setLastStart(0);
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see
+     * org.onap.policy.apex.model.basicmodel.concepts.AxConcept#validate(org.onap.policy.apex.model.
+     * basicmodel.concepts.AxValidationResult)
+     */
+    @Override
+    public AxValidationResult validate(final AxValidationResult result) {
+        if (key.equals(AxReferenceKey.getNullKey())) {
+            result.addValidationMessage(
+                    new AxValidationMessage(key, this.getClass(), ValidationResult.INVALID, "key is a null key"));
+        }
+
+        return key.validate(result);
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.basicmodel.concepts.AxConcept#clean()
+     */
+    @Override
+    public void clean() {
+        key.clean();
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.basicmodel.concepts.AxConcept#toString()
+     */
+    @Override
+    public String toString() {
+        final StringBuilder builder = new StringBuilder();
+        builder.append(this.getClass().getSimpleName());
+        builder.append(":(");
+        builder.append("engineKey=");
+        builder.append(key);
+        builder.append(",timeStamp=");
+        builder.append(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").format(timeStamp));
+        builder.append(",eventCount=");
+        builder.append(eventCount);
+        builder.append(",lastExecutionTime=");
+        builder.append(lastExecutionTime);
+        builder.append(",averageExecutionTime=");
+        builder.append(averageExecutionTime);
+        builder.append(",upTime=");
+        builder.append(getUpTime());
+        builder.append(")");
+        return builder.toString();
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see
+     * org.onap.policy.apex.model.basicmodel.concepts.AxConcept#copyTo(org.onap.policy.apex.model.
+     * basicmodel.concepts.AxConcept)
+     */
+    @Override
+    public AxConcept copyTo(final AxConcept targetObject) {
+        Assertions.argumentNotNull(targetObject, "target may not be null");
+
+        final Object copyObject = targetObject;
+        Assertions.instanceOf(copyObject, AxEngineStats.class);
+
+        final AxEngineStats copy = ((AxEngineStats) copyObject);
+        copy.setKey(new AxReferenceKey(key));
+        copy.setTimeStamp(timeStamp);
+        copy.setEventCount(eventCount);
+        copy.setLastExecutionTime(lastExecutionTime);
+        copy.setAverageExecutionTime(averageExecutionTime);
+        copy.setUpTime(upTime);
+        copy.setLastStart(lastStart);
+
+        return copy;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.basicmodel.concepts.AxConcept#hashCode()
+     */
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + key.hashCode();
+        result = prime * result + (int) (timeStamp ^ (timeStamp >>> HASH_CODE_PRIME));
+        result = prime * result + (int) (eventCount ^ (eventCount >>> HASH_CODE_PRIME));
+        result = prime * result + (int) (lastExecutionTime ^ (lastExecutionTime >>> HASH_CODE_PRIME));
+        result = prime * result + ((int) averageExecutionTime ^ ((int) averageExecutionTime >>> HASH_CODE_PRIME));
+        result = prime * result + (int) (upTime ^ (upTime >>> HASH_CODE_PRIME));
+        result = prime * result + (int) (getLastStart() ^ (getLastStart() >>> HASH_CODE_PRIME));
+        return result;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.policy.apex.model.basicmodel.concepts.AxConcept#equals(java.lang.Object)
+     */
+    @Override
+    public boolean equals(final Object obj) {
+        if (obj == null) {
+            return false;
+        }
+        if (this == obj) {
+            return true;
+        }
+
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+
+        final AxEngineStats other = (AxEngineStats) obj;
+        if (!key.equals(other.key)) {
+            return false;
+        }
+        if (timeStamp != other.timeStamp) {
+            return false;
+        }
+        if (eventCount != other.eventCount) {
+            return false;
+        }
+        if (lastExecutionTime != other.lastExecutionTime) {
+            return false;
+        }
+        if (averageExecutionTime != other.averageExecutionTime) {
+            return false;
+        }
+        if (upTime != other.upTime) {
+            return false;
+        }
+        return getLastStart() == other.getLastStart();
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see java.lang.Comparable#compareTo(java.lang.Object)
+     */
+    @Override
+    public int compareTo(final AxConcept otherObj) {
+        if (otherObj == null) {
+            return -1;
+        }
+        if (this == otherObj) {
+            return 0;
+        }
+        if (getClass() != otherObj.getClass()) {
+            return this.hashCode() - otherObj.hashCode();
+        }
+
+        final AxEngineStats other = (AxEngineStats) otherObj;
+        if (!key.equals(other.key)) {
+            return key.compareTo(other.key);
+        }
+        if (timeStamp != other.timeStamp) {
+            return (int) (timeStamp - other.timeStamp);
+        }
+        if (eventCount != other.eventCount) {
+            return (int) (eventCount - other.eventCount);
+        }
+        if (lastExecutionTime != other.lastExecutionTime) {
+            return (int) (lastExecutionTime - other.lastExecutionTime);
+        }
+        if (averageExecutionTime != other.averageExecutionTime) {
+            return (int) (averageExecutionTime - other.averageExecutionTime);
+        }
+        if (upTime != other.upTime) {
+            return (int) (upTime - other.upTime);
+        }
+        if (getLastStart() != other.getLastStart()) {
+            return (int) (getLastStart() - other.getLastStart());
+        }
+
+        return 0;
+    }
+}
diff --git a/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/package-info.java b/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/package-info.java
new file mode 100644
index 000000000..ea47c6993
--- /dev/null
+++ b/model/engine-model/src/main/java/org/onap/policy/apex/model/enginemodel/concepts/package-info.java
@@ -0,0 +1,34 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. 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.
+ * 
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+/**
+ * Contains the concepts required to receive state information and statistcs from running APEX
+ * engines.
+ * 
+ * @author Liam Fallon (liam.fallon@ericsson.com)
+ */
+@XmlSchema(namespace = "http://www.onap.org/policy/apex-pdp", elementFormDefault = XmlNsForm.QUALIFIED,
+        xmlns = {@XmlNs(namespaceURI = "http://www.onap.org/policy/apex-pdp", prefix = "")})
+
+package org.onap.policy.apex.model.enginemodel.concepts;
+
+import javax.xml.bind.annotation.XmlNs;
+import javax.xml.bind.annotation.XmlNsForm;
+import javax.xml.bind.annotation.XmlSchema;