Prepare codebase for dynamic DMaaP configuration

From now on, there is only one single place
where we can create whole app core concerning sending events
and it has a single entry point, based on DMaaP configuration.
It can be used to rebuild part of app that is responsible
for sending events dynamically.
Changes are in scope for the dynamic DMaaP config feature.
+ bumped up code coverage a bit

Change-Id: Iecc8c4e534ae9b781f47e3616409271ba83169c8
Signed-off-by: PawelSzalapski <pawel.szalapski@nokia.com>
Issue-ID: DCAEGEN2-517

7 files changed, 580 insertions, 0 deletions

diff --git a/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPConfigurationParser.java b/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPConfigurationParser.java
new file mode 100644
index 00000000..bef14448
--- /dev/null
+++ b/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPConfigurationParser.java
@@ -0,0 +1,108 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * org.onap.dcaegen2.collectors.ves
+ * ================================================================================
+ * Copyright (C) 2018 Nokia. 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.dcae.commonFunction.event.publishing;
+
+import static io.vavr.API.List;
+import static io.vavr.API.Try;
+import static io.vavr.API.Tuple;
+import static io.vavr.API.unchecked;
+import static org.onap.dcae.commonFunction.event.publishing.VavrUtils.enhanceError;
+import static org.onap.dcae.commonFunction.event.publishing.VavrUtils.f;
+
+import io.vavr.collection.List;
+import io.vavr.collection.Map;
+import io.vavr.control.Option;
+import io.vavr.control.Try;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.onap.dcae.commonFunction.AnyNode;
+
+/**
+ * @author Pawel Szalapski (pawel.szalapski@nokia.com)
+ */
+@SuppressWarnings("mapFailure takes a generic varargs, unchecked because of Javas type system limitation, actually safe to do")
+public final class DMaaPConfigurationParser {
+
+    public static Try<Map<String, PublisherConfig>> parseToDomainMapping(Path configLocation) {
+        return readFromFile(configLocation)
+            .flatMap(DMaaPConfigurationParser::toJSON)
+            .flatMap(DMaaPConfigurationParser::toConfigMap);
+    }
+
+    private static Try<String> readFromFile(Path configLocation) {
+        return Try(() -> new String(Files.readAllBytes(configLocation)))
+            .mapFailure(enhanceError(f("Could not read DMaaP configuration from location: '%s'", configLocation)));
+    }
+
+    private static Try<AnyNode> toJSON(String config) {
+        return Try(() -> AnyNode.fromString(config))
+            .mapFailure(enhanceError(f("DMaaP configuration '%s' is not a valid JSON document", config)));
+    }
+
+    private static Try<Map<String, PublisherConfig>> toConfigMap(AnyNode config) {
+        return Try(() -> usesLegacyFormat(config) ? parseLegacyFormat(config) : parseNewFormat(config))
+            .mapFailure(enhanceError(
+                f("Parsing DMaaP configuration: '%s' failed, probably it is in unexpected format", config)));
+    }
+
+    private static boolean usesLegacyFormat(AnyNode dMaaPConfig) {
+        return dMaaPConfig.has("channels");
+    }
+
+    private static Map<String, PublisherConfig> parseLegacyFormat(AnyNode root) {
+        return root.get("channels").toList().toMap(
+            channel -> channel.get("name").toString(),
+            channel -> {
+                String destinationsStr = channel.getAsOption("cambria.url")
+                    .getOrElse(channel.getAsOption("cambria.hosts").get())
+                    .toString();
+                String topic = channel.get("cambria.topic").toString();
+                Option<String> maybeUser = channel.getAsOption("basicAuthUsername").map(AnyNode::toString);
+                Option<String> maybePassword = channel.getAsOption("basicAuthPassword").map(AnyNode::toString);
+                List<String> destinations = List(destinationsStr.split(","));
+                return buildBasedOnAuth(maybeUser, maybePassword, topic, destinations);
+            });
+    }
+
+    private static Map<String, PublisherConfig> parseNewFormat(AnyNode root) {
+        return root.keys().toMap(
+            channelName -> channelName,
+            channelName -> {
+                AnyNode channelConfig = root.get(channelName);
+                Option<String> maybeUser = channelConfig.getAsOption("aaf_username").map(AnyNode::toString);
+                Option<String> maybePassword = channelConfig.getAsOption("aaf_password").map(AnyNode::toString);
+                URL topicURL = unchecked(
+                    () -> new URL(channelConfig.get("dmaap_info").get("topic_url").toString())).apply();
+                String[] pathSegments = topicURL.getPath().substring(1).split("/");
+                String topic = pathSegments[1];
+                String destination = "events".equals(pathSegments[0]) ? topicURL.getAuthority() : topicURL.getHost();
+                List<String> destinations = List(destination);
+                return buildBasedOnAuth(maybeUser, maybePassword, topic, destinations);
+            });
+    }
+
+    private static PublisherConfig buildBasedOnAuth(Option<String> maybeUser, Option<String> maybePassword,
+                                                    String topic, List<String> destinations) {
+        return maybeUser.flatMap(user -> maybePassword.map(password -> Tuple(user, password)))
+            .map(credentials -> new PublisherConfig(destinations, topic, credentials._1, credentials._2))
+            .getOrElse(new PublisherConfig(destinations, topic));
+    }
+}
diff --git a/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPEventPublisher.java b/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPEventPublisher.java
new file mode 100644
index 00000000..fd9b3ae1
--- /dev/null
+++ b/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPEventPublisher.java
@@ -0,0 +1,99 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * org.onap.dcaegen2.collectors.ves
+ * ================================================================================
+ * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
+ * Copyright (C) 2018 Nokia. 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.dcae.commonFunction.event.publishing;
+
+import static org.onap.dcae.commonFunction.event.publishing.VavrUtils.f;
+
+import com.att.nsa.cambria.client.CambriaBatchingPublisher;
+import com.att.nsa.clock.SaClock;
+import com.att.nsa.logging.LoggingContext;
+import com.att.nsa.logging.log4j.EcompFields;
+import io.vavr.collection.Map;
+import io.vavr.control.Try;
+import java.io.IOException;
+import org.json.JSONObject;
+import org.onap.dcae.commonFunction.VESLogger;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * @author Pawel Szalapski (pawel.szalapski@nokia.com)
+ */
+class DMaaPEventPublisher implements EventPublisher {
+    private static final int PENDING_MESSAGE_LOG_THRESHOLD = 100;
+    private static final String VES_UNIQUE_ID = "VESuniqueId";
+    private static final Logger log = LoggerFactory.getLogger(DMaaPEventPublisher.class);
+    private final DMaaPPublishersCache publishersCache;
+    private final Logger outputLogger;
+
+    DMaaPEventPublisher(DMaaPPublishersCache DMaaPPublishersCache,
+                        Logger outputLogger) {
+        this.publishersCache = DMaaPPublishersCache;
+        this.outputLogger = outputLogger;
+    }
+
+    @Override
+    public void sendEvent(JSONObject event, String domain) {
+        clearVesUniqueIdFromEvent(event);
+        publishersCache.getPublisher(domain)
+            .onEmpty(() ->
+                log.warn(f("Could not find event publisher for domain: '%s', dropping message: '%s'", domain, event)))
+            .forEach(publisher -> sendEvent(event, domain, publisher));
+    }
+
+    @Override
+    public void reconfigure(Map<String, PublisherConfig> dMaaPConfig) {
+        publishersCache.reconfigure(dMaaPConfig);
+    }
+
+    private void sendEvent(JSONObject event, String domain, CambriaBatchingPublisher publisher) {
+        Try.run(() -> uncheckedSendEvent(event, domain, publisher))
+            .onFailure(exc -> closePublisher(event, domain, exc));
+    }
+
+    private void uncheckedSendEvent(JSONObject event, String domain, CambriaBatchingPublisher publisher)
+        throws IOException {
+        int pendingMsgs = publisher.send("MyPartitionKey", event.toString());
+        if (pendingMsgs > PENDING_MESSAGE_LOG_THRESHOLD) {
+            log.info("Pending messages count: " + pendingMsgs);
+        }
+        String infoMsg = f("Event: '%s' scheduled to be send asynchronously on domain: '%s'", event, domain);
+        log.info(infoMsg);
+        outputLogger.info(infoMsg);
+    }
+
+    private void closePublisher(JSONObject event, String domain, Throwable e) {
+        log.error(f("Unable to schedule event: '%s' on domain: '%s'. Closing publisher and dropping message.",
+            event, domain), e);
+        publishersCache.closePublisherFor(domain);
+    }
+
+    private void clearVesUniqueIdFromEvent(JSONObject event) {
+        if (event.has(VES_UNIQUE_ID)) {
+            String uuid = event.get(VES_UNIQUE_ID).toString();
+            LoggingContext localLC = VESLogger.getLoggingContextForThread(uuid);
+            localLC.put(EcompFields.kBeginTimestampMs, SaClock.now());
+            log.debug("Removing VESuniqueid object from event");
+            event.remove(VES_UNIQUE_ID);
+        }
+    }
+}
diff --git a/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPPublishersBuilder.java b/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPPublishersBuilder.java
new file mode 100644
index 00000000..a7865a45
--- /dev/null
+++ b/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPPublishersBuilder.java
@@ -0,0 +1,62 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * org.onap.dcaegen2.collectors.ves
+ * ================================================================================
+ * Copyright (C) 2018 Nokia. 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.dcae.commonFunction.event.publishing;
+
+import static io.vavr.API.Try;
+import static org.onap.dcae.commonFunction.event.publishing.VavrUtils.enhanceError;
+import static org.onap.dcae.commonFunction.event.publishing.VavrUtils.f;
+
+import com.att.nsa.cambria.client.CambriaBatchingPublisher;
+import com.att.nsa.cambria.client.CambriaClientBuilders;
+import com.att.nsa.cambria.client.CambriaClientBuilders.PublisherBuilder;
+import io.vavr.control.Try;
+
+/**
+ * @author Pawel Szalapski (pawel.szalapski@nokia.com)
+ */
+final class DMaaPPublishersBuilder {
+
+    @SuppressWarnings("mapFailure takes a generic varargs, unchecked because of Javas type system limitation, actually safe to do")
+    static Try<CambriaBatchingPublisher> buildPublisher(PublisherConfig config) {
+        return Try(() -> builder(config).build())
+            .mapFailure(enhanceError(f("DMaaP client builder throws exception for this configuration: '%s'", config)));
+    }
+
+    private static PublisherBuilder builder(PublisherConfig config) {
+        if (config.isSecured()) {
+            return authenticatedBuilder(config);
+        } else {
+            return unAuthenticatedBuilder(config);
+        }
+    }
+
+    private static PublisherBuilder authenticatedBuilder(PublisherConfig config) {
+        return unAuthenticatedBuilder(config)
+            .usingHttps()
+            .authenticatedByHttp(config.userName().get(), config.password().get());
+    }
+
+    private static PublisherBuilder unAuthenticatedBuilder(PublisherConfig config) {
+        return new CambriaClientBuilders.PublisherBuilder()
+            .usingHosts(config.destinations().mkString(","))
+            .onTopic(config.topic())
+            .logSendFailuresAfter(5);
+    }
+}
diff --git a/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPPublishersCache.java b/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPPublishersCache.java
new file mode 100644
index 00000000..102d2774
--- /dev/null
+++ b/src/main/java/org/onap/dcae/commonFunction/event/publishing/DMaaPPublishersCache.java
@@ -0,0 +1,124 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * org.onap.dcaegen2.collectors.ves
+ * ================================================================================
+ * Copyright (C) 2017-2018 AT&T Intellectual Property. All rights reserved.
+ * Copyright (C) 2018 Nokia. 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.dcae.commonFunction.event.publishing;
+
+import static io.vavr.API.Option;
+import static org.onap.dcae.commonFunction.event.publishing.VavrUtils.f;
+
+import com.att.nsa.cambria.client.CambriaBatchingPublisher;
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.common.cache.RemovalListener;
+import com.google.common.cache.RemovalNotification;
+import io.vavr.collection.Map;
+import io.vavr.control.Option;
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import javax.annotation.Nonnull;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * @author Pawel Szalapski (pawel.szalapski@nokia.com)
+ */
+class DMaaPPublishersCache {
+
+    private static final Logger log = LoggerFactory.getLogger(DMaaPPublishersCache.class);
+    private final LoadingCache<String, CambriaBatchingPublisher> publishersCache;
+    private AtomicReference<Map<String, PublisherConfig>> dMaaPConfiguration;
+
+    DMaaPPublishersCache(Map<String, PublisherConfig> dMaaPConfiguration) {
+        this.dMaaPConfiguration = new AtomicReference<>(dMaaPConfiguration);
+        this.publishersCache = CacheBuilder.newBuilder()
+            .removalListener(new OnPublisherRemovalListener())
+            .build(new CambriaPublishersCacheLoader());
+    }
+
+    DMaaPPublishersCache(CambriaPublishersCacheLoader dMaaPPublishersCacheLoader,
+                         OnPublisherRemovalListener onPublisherRemovalListener,
+                         Map<String, PublisherConfig> dMaaPConfiguration) {
+        this.dMaaPConfiguration = new AtomicReference<>(dMaaPConfiguration);
+        this.publishersCache = CacheBuilder.newBuilder()
+            .removalListener(onPublisherRemovalListener)
+            .build(dMaaPPublishersCacheLoader);
+    }
+
+    Option<CambriaBatchingPublisher> getPublisher(String streamID) {
+        try {
+            return Option(publishersCache.getUnchecked(streamID));
+        } catch (Exception e) {
+            log.warn("Could not create / load Cambria Publisher for streamID", e);
+            return Option.none();
+        }
+    }
+
+    void closePublisherFor(String streamId) {
+        publishersCache.invalidate(streamId);
+    }
+
+    synchronized void reconfigure(Map<String, PublisherConfig> newConfig) {
+        Map<String, PublisherConfig> currentConfig = dMaaPConfiguration.get();
+        Map<String, PublisherConfig> removedConfigurations = currentConfig
+            .filterKeys(domain -> !newConfig.containsKey(domain));
+        Map<String, PublisherConfig> changedConfigurations = newConfig
+            .filterKeys(e -> currentConfig.containsKey(e) && !currentConfig.get(e).equals(newConfig.get(e)));
+        dMaaPConfiguration.set(newConfig);
+        removedConfigurations.merge(changedConfigurations).forEach(e -> publishersCache.invalidate(e._1));
+    }
+
+    static class OnPublisherRemovalListener implements RemovalListener<String, CambriaBatchingPublisher> {
+
+        @Override
+        public void onRemoval(@Nonnull RemovalNotification<String, CambriaBatchingPublisher> notification) {
+            CambriaBatchingPublisher publisher = notification.getValue();
+            if (publisher != null) { // The value might get Garbage Collected at this moment, regardless of @Nonnull
+                try {
+                    int timeout = 20;
+                    TimeUnit unit = TimeUnit.SECONDS;
+                    java.util.List<?> stuck = publisher.close(timeout, unit);
+                    if (!stuck.isEmpty()) {
+                        log.error(f("Publisher got stuck and did not manage to close in '%s' '%s', "
+                            + "%s messages were dropped", stuck.size(), timeout, unit));
+                    }
+                } catch (InterruptedException | IOException e) {
+                    log.error("Could not close Cambria publisher, some messages might have been dropped", e);
+                }
+            }
+        }
+    }
+
+    class CambriaPublishersCacheLoader extends CacheLoader<String, CambriaBatchingPublisher> {
+
+        @Override
+        public CambriaBatchingPublisher load(@Nonnull String domain) {
+            return dMaaPConfiguration.get()
+                .get(domain)
+                .toTry(() -> new RuntimeException(
+                    f("DMaaP configuration contains no configuration for domain: '%s'", domain)))
+                .flatMap(DMaaPPublishersBuilder::buildPublisher)
+                .get();
+        }
+    }
+
+}
diff --git a/src/main/java/org/onap/dcae/commonFunction/event/publishing/EventPublisher.java b/src/main/java/org/onap/dcae/commonFunction/event/publishing/EventPublisher.java
new file mode 100644
index 00000000..9cd718f8
--- /dev/null
+++ b/src/main/java/org/onap/dcae/commonFunction/event/publishing/EventPublisher.java
@@ -0,0 +1,38 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * org.onap.dcaegen2.collectors.ves
+ * ================================================================================
+ * Copyright (C) 2018 Nokia. 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.dcae.commonFunction.event.publishing;
+
+import io.vavr.collection.Map;
+import org.json.JSONObject;
+import org.slf4j.Logger;
+
+/**
+ * @author Pawel Szalapski (pawel.szalapski@nokia.com)
+ */
+public interface EventPublisher {
+
+    static EventPublisher createPublisher(Logger outputLogger, Map<String, PublisherConfig> dMaaPConfig) {
+        return new DMaaPEventPublisher(new DMaaPPublishersCache(dMaaPConfig), outputLogger);
+    }
+
+    void sendEvent(JSONObject event, String domain);
+
+    void reconfigure(Map<String, PublisherConfig> dMaaPConfig);
+}
diff --git a/src/main/java/org/onap/dcae/commonFunction/event/publishing/PublisherConfig.java b/src/main/java/org/onap/dcae/commonFunction/event/publishing/PublisherConfig.java
new file mode 100644
index 00000000..4a056778
--- /dev/null
+++ b/src/main/java/org/onap/dcae/commonFunction/event/publishing/PublisherConfig.java
@@ -0,0 +1,98 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * org.onap.dcaegen2.collectors.ves
+ * ================================================================================
+ * Copyright (C) 2018 Nokia. 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.dcae.commonFunction.event.publishing;
+
+import io.vavr.collection.List;
+import io.vavr.control.Option;
+import java.util.Objects;
+
+/**
+ * @author Pawel Szalapski (pawel.szalapski@nokia.com)
+ */
+public final class PublisherConfig {
+
+    private final List<String> destinations;
+    private final String topic;
+    private String userName;
+    private String password;
+
+    PublisherConfig(List<String> destinations, String topic) {
+        this.destinations = destinations;
+        this.topic = topic;
+    }
+
+    PublisherConfig(List<String> destinations, String topic, String userName, String password) {
+        this.destinations = destinations;
+        this.topic = topic;
+        this.userName = userName;
+        this.password = password;
+    }
+
+    List<String> destinations() {
+        return destinations;
+    }
+
+    String topic() {
+        return topic;
+    }
+
+    Option<String> userName() {
+        return Option.of(userName);
+    }
+
+    Option<String> password() {
+        return Option.of(password);
+    }
+
+    boolean isSecured() {
+        return userName().isDefined() && password().isDefined();
+    }
+
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        PublisherConfig that = (PublisherConfig) o;
+        return Objects.equals(destinations, that.destinations) &&
+            Objects.equals(topic, that.topic) &&
+            Objects.equals(userName, that.userName) &&
+            Objects.equals(password, that.password);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(destinations, topic, userName, password);
+    }
+
+    @Override
+    public String toString() {
+        return "PublisherConfig{" +
+            "destinations=" + destinations +
+            ", topic='" + topic + '\'' +
+            ", userName='" + userName + '\'' +
+            ", password='" + password + '\'' +
+            '}';
+    }
+}
diff --git a/src/main/java/org/onap/dcae/commonFunction/event/publishing/VavrUtils.java b/src/main/java/org/onap/dcae/commonFunction/event/publishing/VavrUtils.java
new file mode 100644
index 00000000..9bf3ef8c
--- /dev/null
+++ b/src/main/java/org/onap/dcae/commonFunction/event/publishing/VavrUtils.java
@@ -0,0 +1,51 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * org.onap.dcaegen2.collectors.ves
+ * ================================================================================
+ * Copyright (C) 2018 Nokia. 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.dcae.commonFunction.event.publishing;
+
+import static io.vavr.API.$;
+
+import io.vavr.API;
+import io.vavr.API.Match.Case;
+
+/**
+ * @author Pawel Szalapski (pawel.szalapski@nokia.com)
+ */
+final class VavrUtils {
+
+    private VavrUtils() {
+        // utils aggregator
+    }
+
+    /**
+     * Shortcut for 'string interpolation'
+     */
+    static String f(String msg, Object... args) {
+        return String.format(msg, args);
+    }
+
+    /**
+     * Wrap failure with a more descriptive message of what has failed and chain original cause. Used to provide a
+     * context for errors instead of raw exception.
+     */
+    static Case<Throwable, Throwable> enhanceError(String msg) {
+        return API.Case($(), e -> new RuntimeException(msg, e));
+    }
+
+}