open62541/src/pubsub/ua_pubsub.c

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright (c) 2017-2018 Fraunhofer IOSB (Author: Andreas Ebner)
 */

#include "ua_types_encoding_binary.h"
#include "ua_server_pubsub.h"
#include "server/ua_server_internal.h"
#include "ua_pubsub.h"
#include "ua_pubsub_manager.h"
#include "ua_pubsub_networkmessage.h"

#ifdef UA_ENABLE_PUBSUB /* conditional compilation */
#ifdef UA_ENABLE_PUBSUB_INFORMATIONMODEL
#include "ua_pubsub_ns0.h"
#endif

/**********************************************/
/*               Connection                   */
/**********************************************/

UA_StatusCode
UA_PubSubConnectionConfig_copy(const UA_PubSubConnectionConfig *src,
                               UA_PubSubConnectionConfig *dst) {
    UA_StatusCode retVal = UA_STATUSCODE_GOOD;
    memcpy(dst, src, sizeof(UA_PubSubConnectionConfig));
    retVal |= UA_String_copy(&src->name, &dst->name);
    retVal |= UA_Variant_copy(&src->address, &dst->address);
    retVal |= UA_String_copy(&src->transportProfileUri, &dst->transportProfileUri);
    retVal |= UA_Variant_copy(&src->connectionTransportSettings, &dst->connectionTransportSettings);
    if(src->connectionPropertiesSize > 0){
        dst->connectionProperties = (UA_KeyValuePair *)
            UA_calloc(src->connectionPropertiesSize, sizeof(UA_KeyValuePair));
        if(!dst->connectionProperties){
            return UA_STATUSCODE_BADOUTOFMEMORY;
        }
        for(size_t i = 0; i < src->connectionPropertiesSize; i++){
            retVal |= UA_QualifiedName_copy(&src->connectionProperties[i].key,
                                            &dst->connectionProperties[i].key);
            retVal |= UA_Variant_copy(&src->connectionProperties[i].value,
                                      &dst->connectionProperties[i].value);
        }
    }
    return retVal;
}

UA_StatusCode
UA_Server_getPubSubConnectionConfig(UA_Server *server, const UA_NodeId connection,
                                    UA_PubSubConnectionConfig *config) {
    if(!config)
        return UA_STATUSCODE_BADINVALIDARGUMENT;

    UA_PubSubConnection *currentPubSubConnection =
        UA_PubSubConnection_findConnectionbyId(server, connection);
    if(!currentPubSubConnection)
        return UA_STATUSCODE_BADNOTFOUND;

    UA_PubSubConnectionConfig tmpPubSubConnectionConfig;
    //deep copy of the actual config
    UA_PubSubConnectionConfig_copy(currentPubSubConnection->config, &tmpPubSubConnectionConfig);
    *config = tmpPubSubConnectionConfig;
    return UA_STATUSCODE_GOOD;
}

UA_PubSubConnection *
UA_PubSubConnection_findConnectionbyId(UA_Server *server, UA_NodeId connectionIdentifier) {
    for(size_t i = 0; i < server->pubSubManager.connectionsSize; i++){
        if(UA_NodeId_equal(&connectionIdentifier, &server->pubSubManager.connections[i].identifier)){
            return &server->pubSubManager.connections[i];
        }
    }
    return NULL;
}

void
UA_PubSubConnectionConfig_deleteMembers(UA_PubSubConnectionConfig *connectionConfig) {
    UA_String_deleteMembers(&connectionConfig->name);
    UA_String_deleteMembers(&connectionConfig->transportProfileUri);
    UA_Variant_deleteMembers(&connectionConfig->connectionTransportSettings);
    UA_Variant_deleteMembers(&connectionConfig->address);
    for(size_t i = 0; i < connectionConfig->connectionPropertiesSize; i++){
        UA_QualifiedName_deleteMembers(&connectionConfig->connectionProperties[i].key);
        UA_Variant_deleteMembers(&connectionConfig->connectionProperties[i].value);
    }
    UA_free(connectionConfig->connectionProperties);
}

void
UA_PubSubConnection_deleteMembers(UA_Server *server, UA_PubSubConnection *connection) {
    //delete connection config
    UA_PubSubConnectionConfig_deleteMembers(connection->config);
    //remove contained WriterGroups
    UA_WriterGroup *writerGroup, *tmpWriterGroup;
    LIST_FOREACH_SAFE(writerGroup, &connection->writerGroups, listEntry, tmpWriterGroup){
        UA_Server_removeWriterGroup(server, writerGroup->identifier);
    }
    UA_NodeId_deleteMembers(&connection->identifier);
    if(connection->channel){
        connection->channel->close(connection->channel);
    }
    UA_free(connection->config);
}

UA_StatusCode
UA_Server_addWriterGroup(UA_Server *server, const UA_NodeId connection,
                         const UA_WriterGroupConfig *writerGroupConfig,
                         UA_NodeId *writerGroupIdentifier) {
    UA_StatusCode retVal = UA_STATUSCODE_GOOD;
    if(!writerGroupConfig)
        return UA_STATUSCODE_BADINVALIDARGUMENT;
    //search the connection by the given connectionIdentifier
    UA_PubSubConnection *currentConnectionContext =
        UA_PubSubConnection_findConnectionbyId(server, connection);
    if(!currentConnectionContext)
        return UA_STATUSCODE_BADNOTFOUND;

    //allocate memory for new WriterGroup
    UA_WriterGroup *newWriterGroup = (UA_WriterGroup *) UA_calloc(1, sizeof(UA_WriterGroup));
    if (!newWriterGroup)
        return UA_STATUSCODE_BADOUTOFMEMORY;

    newWriterGroup->linkedConnection = currentConnectionContext->identifier;
    UA_PubSubManager_generateUniqueNodeId(server, &newWriterGroup->identifier);
    if(writerGroupIdentifier){
        UA_NodeId_copy(&newWriterGroup->identifier, writerGroupIdentifier);
    }
    UA_WriterGroupConfig tmpWriterGroupConfig;
    //deep copy of the config
    retVal |= UA_WriterGroupConfig_copy(writerGroupConfig, &tmpWriterGroupConfig);
    newWriterGroup->config = tmpWriterGroupConfig;
    retVal |= UA_WriterGroup_addPublishCallback(server, newWriterGroup);
    LIST_INSERT_HEAD(&currentConnectionContext->writerGroups, newWriterGroup, listEntry);
#ifdef UA_ENABLE_PUBSUB_INFORMATIONMODEL
    addWriterGroupRepresentation(server, newWriterGroup);
#endif
    return retVal;
}

UA_StatusCode
UA_Server_removeWriterGroup(UA_Server *server, const UA_NodeId writerGroup){
    UA_WriterGroup *wg = UA_WriterGroup_findWGbyId(server, writerGroup);
    if(!wg)
        return UA_STATUSCODE_BADNOTFOUND;

    UA_PubSubConnection *connection =
        UA_PubSubConnection_findConnectionbyId(server, wg->linkedConnection);
    if(!connection)
        return UA_STATUSCODE_BADNOTFOUND;

    //unregister the publish callback
    if(UA_PubSubManager_removeRepeatedPubSubCallback(server, wg->publishCallbackId) != UA_STATUSCODE_GOOD)
        return UA_STATUSCODE_BADINTERNALERROR;
#ifdef UA_ENABLE_PUBSUB_INFORMATIONMODEL
    removeWriterGroupRepresentation(server, wg);
#endif
    UA_WriterGroup_deleteMembers(server, wg);
    UA_free(wg);
    return UA_STATUSCODE_GOOD;
}

/**********************************************/
/*               PublishedDataSet             */
/**********************************************/

UA_StatusCode
UA_PublishedDataSetConfig_copy(const UA_PublishedDataSetConfig *src,
                               UA_PublishedDataSetConfig *dst) {
    UA_StatusCode retVal = UA_STATUSCODE_GOOD;
    memcpy(dst, src, sizeof(UA_PublishedDataSetConfig));
    retVal |= UA_String_copy(&src->name, &dst->name);
    switch(src->publishedDataSetType){
        case UA_PUBSUB_DATASET_PUBLISHEDITEMS:
            //no additional items
            break;
        case UA_PUBSUB_DATASET_PUBLISHEDITEMS_TEMPLATE:
            if (src->config.itemsTemplate.variablesToAddSize > 0){
                dst->config.itemsTemplate.variablesToAdd = (UA_PublishedVariableDataType *) UA_calloc(
                        src->config.itemsTemplate.variablesToAddSize, sizeof(UA_PublishedVariableDataType));
            }
            for(size_t i = 0; i < src->config.itemsTemplate.variablesToAddSize; i++){
                retVal |= UA_PublishedVariableDataType_copy(&src->config.itemsTemplate.variablesToAdd[i],
                                                            &dst->config.itemsTemplate.variablesToAdd[i]);
            }
            retVal |= UA_DataSetMetaDataType_copy(&src->config.itemsTemplate.metaData,
                                                  &dst->config.itemsTemplate.metaData);
            break;
        default:
            return UA_STATUSCODE_BADINVALIDARGUMENT;
    }
    return retVal;
}

UA_StatusCode
UA_Server_getPublishedDataSetConfig(UA_Server *server, const UA_NodeId pds,
                                    UA_PublishedDataSetConfig *config){
    if(!config)
        return UA_STATUSCODE_BADINVALIDARGUMENT;

    UA_PublishedDataSet *currentPublishedDataSet = UA_PublishedDataSet_findPDSbyId(server, pds);
    if(!currentPublishedDataSet)
        return UA_STATUSCODE_BADNOTFOUND;

    UA_PublishedDataSetConfig tmpPublishedDataSetConfig;
    //deep copy of the actual config
    UA_PublishedDataSetConfig_copy(&currentPublishedDataSet->config, &tmpPublishedDataSetConfig);
    *config = tmpPublishedDataSetConfig;
    return UA_STATUSCODE_GOOD;
}

UA_PublishedDataSet *
UA_PublishedDataSet_findPDSbyId(UA_Server *server, UA_NodeId identifier){
    for(size_t i = 0; i < server->pubSubManager.publishedDataSetsSize; i++){
        if(UA_NodeId_equal(&server->pubSubManager.publishedDataSets[i].identifier, &identifier)){
            return &server->pubSubManager.publishedDataSets[i];
        }
    }
    return NULL;
}

void
UA_PublishedDataSetConfig_deleteMembers(UA_PublishedDataSetConfig *pdsConfig){
    //delete pds config
    UA_String_deleteMembers(&pdsConfig->name);
    switch (pdsConfig->publishedDataSetType){
        case UA_PUBSUB_DATASET_PUBLISHEDITEMS:
            //no additional items
            break;
        case UA_PUBSUB_DATASET_PUBLISHEDITEMS_TEMPLATE:
            if (pdsConfig->config.itemsTemplate.variablesToAddSize > 0){
                for(size_t i = 0; i < pdsConfig->config.itemsTemplate.variablesToAddSize; i++){
                    UA_PublishedVariableDataType_deleteMembers(&pdsConfig->config.itemsTemplate.variablesToAdd[i]);
                }
                UA_free(pdsConfig->config.itemsTemplate.variablesToAdd);
            }
            UA_DataSetMetaDataType_deleteMembers(&pdsConfig->config.itemsTemplate.metaData);
            break;
        default:
            break;
    }
}

void
UA_PublishedDataSet_deleteMembers(UA_Server *server, UA_PublishedDataSet *publishedDataSet){
    UA_PublishedDataSetConfig_deleteMembers(&publishedDataSet->config);
    //delete PDS
    UA_DataSetMetaDataType_deleteMembers(&publishedDataSet->dataSetMetaData);
    UA_DataSetField *field, *tmpField;
    LIST_FOREACH_SAFE(field, &publishedDataSet->fields, listEntry, tmpField) {
        UA_Server_removeDataSetField(server, field->identifier);
    }
    UA_NodeId_deleteMembers(&publishedDataSet->identifier);
}

UA_DataSetFieldResult
UA_Server_addDataSetField(UA_Server *server, const UA_NodeId publishedDataSet,
                          const UA_DataSetFieldConfig *fieldConfig,
                          UA_NodeId *fieldIdentifier) {
    UA_StatusCode retVal = UA_STATUSCODE_GOOD;
    if(!fieldConfig)
        return (UA_DataSetFieldResult) {UA_STATUSCODE_BADINVALIDARGUMENT, {0, 0}};

    UA_PublishedDataSet *currentDataSet = UA_PublishedDataSet_findPDSbyId(server, publishedDataSet);
    if(currentDataSet == NULL)
        return (UA_DataSetFieldResult) {UA_STATUSCODE_BADNOTFOUND, {0, 0}};

    if(currentDataSet->config.publishedDataSetType != UA_PUBSUB_DATASET_PUBLISHEDITEMS)
        return (UA_DataSetFieldResult) {UA_STATUSCODE_BADNOTIMPLEMENTED, {0, 0}};

    UA_DataSetField *newField = (UA_DataSetField *) UA_calloc(1, sizeof(UA_DataSetField));
    if(!newField)
        return (UA_DataSetFieldResult) {UA_STATUSCODE_BADINTERNALERROR, {0, 0}};

    UA_DataSetFieldConfig tmpFieldConfig;
    retVal |= UA_DataSetFieldConfig_copy(fieldConfig, &tmpFieldConfig);
    newField->config = tmpFieldConfig;
    UA_PubSubManager_generateUniqueNodeId(server, &newField->identifier);
    if(fieldIdentifier != NULL){
        UA_NodeId_copy(&newField->identifier, fieldIdentifier);
    }
    newField->publishedDataSet = currentDataSet->identifier;
    //update major version of parent published data set
    currentDataSet->dataSetMetaData.configurationVersion.majorVersion = UA_PubSubConfigurationVersionTimeDifference();
    LIST_INSERT_HEAD(&currentDataSet->fields, newField, listEntry);
    if(newField->config.field.variable.promotedField)
        currentDataSet->promotedFieldsCount++;
    currentDataSet->fieldSize++;
    UA_DataSetFieldResult result =
        {retVal, {currentDataSet->dataSetMetaData.configurationVersion.majorVersion,
                  currentDataSet->dataSetMetaData.configurationVersion.minorVersion}};
    return result;
}

UA_DataSetFieldResult
UA_Server_removeDataSetField(UA_Server *server, const UA_NodeId dsf) {
    UA_DataSetField *currentField = UA_DataSetField_findDSFbyId(server, dsf);
    if(!currentField)
        return (UA_DataSetFieldResult) {UA_STATUSCODE_BADNOTFOUND, {0, 0}};

    UA_PublishedDataSet *parentPublishedDataSet =
        UA_PublishedDataSet_findPDSbyId(server, currentField->publishedDataSet);
    if(!parentPublishedDataSet)
        return (UA_DataSetFieldResult) {UA_STATUSCODE_BADNOTFOUND, {0, 0}};

    parentPublishedDataSet->fieldSize--;
    if(currentField->config.field.variable.promotedField)
        parentPublishedDataSet->promotedFieldsCount--;
    
    /* update major version of PublishedDataSet */
    parentPublishedDataSet->dataSetMetaData.configurationVersion.majorVersion =
        UA_PubSubConfigurationVersionTimeDifference();
    UA_DataSetField_deleteMembers(currentField);
    UA_free(currentField);
    UA_DataSetFieldResult result =
        {UA_STATUSCODE_GOOD, {parentPublishedDataSet->dataSetMetaData.configurationVersion.majorVersion,
                              parentPublishedDataSet->dataSetMetaData.configurationVersion.minorVersion}};
    return result;
}

/**********************************************/
/*               DataSetWriter                */
/**********************************************/

UA_StatusCode
UA_DataSetWriterConfig_copy(const UA_DataSetWriterConfig *src,
                            UA_DataSetWriterConfig *dst){
    UA_StatusCode retVal = UA_STATUSCODE_GOOD;
    memcpy(dst, src, sizeof(UA_DataSetWriterConfig));
    retVal |= UA_String_copy(&src->name, &dst->name);
    retVal |= UA_String_copy(&src->dataSetName, &dst->dataSetName);
    retVal |= UA_ExtensionObject_copy(&src->messageSettings, &dst->messageSettings);
    dst->dataSetWriterProperties = (UA_KeyValuePair *)
        UA_calloc(src->dataSetWriterPropertiesSize, sizeof(UA_KeyValuePair));
    if(!dst->dataSetWriterProperties)
        return UA_STATUSCODE_BADOUTOFMEMORY;
    for(size_t i = 0; i < src->dataSetWriterPropertiesSize; i++){
        retVal |= UA_KeyValuePair_copy(&src->dataSetWriterProperties[i], &dst->dataSetWriterProperties[i]);
    }
    return retVal;
}

UA_StatusCode
UA_Server_getDataSetWriterConfig(UA_Server *server, const UA_NodeId dsw,
                                 UA_DataSetWriterConfig *config){
    UA_StatusCode retVal = UA_STATUSCODE_GOOD;
    if(!config)
        return UA_STATUSCODE_BADINVALIDARGUMENT;

    UA_DataSetWriter *currentDataSetWriter = UA_DataSetWriter_findDSWbyId(server, dsw);
    if(!currentDataSetWriter)
        return UA_STATUSCODE_BADNOTFOUND;

    UA_DataSetWriterConfig tmpWriterConfig;
    //deep copy of the actual config
    retVal |= UA_DataSetWriterConfig_copy(&currentDataSetWriter->config, &tmpWriterConfig);
    *config = tmpWriterConfig;
    return retVal;
}

UA_DataSetWriter *
UA_DataSetWriter_findDSWbyId(UA_Server *server, UA_NodeId identifier) {
    for(size_t i = 0; i < server->pubSubManager.connectionsSize; i++){
        UA_WriterGroup *tmpWriterGroup;
        LIST_FOREACH(tmpWriterGroup, &server->pubSubManager.connections[i].writerGroups, listEntry){
            UA_DataSetWriter *tmpWriter;
            LIST_FOREACH(tmpWriter, &tmpWriterGroup->writers, listEntry){
                if(UA_NodeId_equal(&tmpWriter->identifier, &identifier)){
                    return tmpWriter;
                }
            }
        }
    }
    return NULL;
}

void
UA_DataSetWriterConfig_deleteMembers(UA_DataSetWriterConfig *pdsConfig) {
    UA_String_deleteMembers(&pdsConfig->name);
    UA_String_deleteMembers(&pdsConfig->dataSetName);
    for(size_t i = 0; i < pdsConfig->dataSetWriterPropertiesSize; i++){
        UA_KeyValuePair_deleteMembers(&pdsConfig->dataSetWriterProperties[i]);
    }
    UA_free(pdsConfig->dataSetWriterProperties);
    UA_ExtensionObject_deleteMembers(&pdsConfig->messageSettings);
}

void
UA_DataSetWriter_deleteMembers(UA_Server *server, UA_DataSetWriter *dataSetWriter){
    UA_DataSetWriterConfig_deleteMembers(&dataSetWriter->config);
    //delete DataSetWriter
    UA_NodeId_deleteMembers(&dataSetWriter->identifier);
    UA_NodeId_deleteMembers(&dataSetWriter->linkedWriterGroup);
    UA_NodeId_deleteMembers(&dataSetWriter->connectedDataSet);
    LIST_REMOVE(dataSetWriter, listEntry);
    //delete lastSamples store
    for(size_t i = 0; i < dataSetWriter->lastSamplesCount; i++){
        UA_DataValue_delete(dataSetWriter->lastSamples[i].value);
    }
    LIST_REMOVE(dataSetWriter, listEntry);
    UA_free(dataSetWriter->lastSamples);
}

/**********************************************/
/*               WriterGroup                  */
/**********************************************/

UA_StatusCode
UA_WriterGroupConfig_copy(const UA_WriterGroupConfig *src,
                          UA_WriterGroupConfig *dst){
    UA_StatusCode retVal = UA_STATUSCODE_GOOD;
    memcpy(dst, src, sizeof(UA_WriterGroupConfig));
    retVal |= UA_String_copy(&src->name, &dst->name);
    retVal |= UA_ExtensionObject_copy(&src->transportSettings, &dst->transportSettings);
    retVal |= UA_ExtensionObject_copy(&src->messageSettings, &dst->messageSettings);
    dst->groupProperties = (UA_KeyValuePair *) UA_calloc(src->groupPropertiesSize, sizeof(UA_KeyValuePair));
    if(!dst->groupProperties)
        return UA_STATUSCODE_BADOUTOFMEMORY;
    for(size_t i = 0; i < src->groupPropertiesSize; i++){
        retVal |= UA_KeyValuePair_copy(&src->groupProperties[i], &dst->groupProperties[i]);
    }
    return retVal;
}

UA_StatusCode
UA_Server_getWriterGroupConfig(UA_Server *server, const UA_NodeId writerGroup,
                               UA_WriterGroupConfig *config){
    UA_StatusCode retVal = UA_STATUSCODE_GOOD;
    if(!config)
        return UA_STATUSCODE_BADINVALIDARGUMENT;

    UA_WriterGroup *currentWriterGroup = UA_WriterGroup_findWGbyId(server, writerGroup);
    if(!currentWriterGroup){
        return UA_STATUSCODE_BADNOTFOUND;
    }
    UA_WriterGroupConfig tmpWriterGroupConfig;
    //deep copy of the actual config
    retVal |= UA_WriterGroupConfig_copy(&currentWriterGroup->config, &tmpWriterGroupConfig);
    *config = tmpWriterGroupConfig;
    return retVal;
}

UA_StatusCode
UA_Server_updateWriterGroupConfig(UA_Server *server, UA_NodeId writerGroupIdentifier,
                                  const UA_WriterGroupConfig *config){
    if(!config)
        return UA_STATUSCODE_BADINVALIDARGUMENT;

    UA_WriterGroup *currentWriterGroup = UA_WriterGroup_findWGbyId(server, writerGroupIdentifier);
    if(!currentWriterGroup)
        return UA_STATUSCODE_BADNOTFOUND;
    //The update functionality will be extended during the next PubSub batches.
    //Currently is only a change of the publishing interval possible.
    if(currentWriterGroup->config.publishingInterval != config->publishingInterval) {
        UA_PubSubManager_removeRepeatedPubSubCallback(server, currentWriterGroup->publishCallbackId);
        currentWriterGroup->config.publishingInterval = config->publishingInterval;
        UA_WriterGroup_addPublishCallback(server, currentWriterGroup);
    } else if (currentWriterGroup->config.priority != config->priority) {
        UA_LOG_WARNING(server->config.logger, UA_LOGCATEGORY_SERVER, "No or unsupported WriterGroup update.");
    }
    return UA_STATUSCODE_GOOD;
}

UA_WriterGroup *
UA_WriterGroup_findWGbyId(UA_Server *server, UA_NodeId identifier){
    for(size_t i = 0; i < server->pubSubManager.connectionsSize; i++){
        UA_WriterGroup *tmpWriterGroup;
        LIST_FOREACH(tmpWriterGroup, &server->pubSubManager.connections[i].writerGroups, listEntry) {
            if(UA_NodeId_equal(&identifier, &tmpWriterGroup->identifier)){
                return tmpWriterGroup;
            }
        }
    }
    return NULL;
}

void
UA_WriterGroupConfig_deleteMembers(UA_WriterGroupConfig *writerGroupConfig){
    //delete writerGroup config
    UA_String_deleteMembers(&writerGroupConfig->name);
    UA_ExtensionObject_deleteMembers(&writerGroupConfig->transportSettings);
    UA_ExtensionObject_deleteMembers(&writerGroupConfig->messageSettings);
    for(size_t i = 0; i < writerGroupConfig->groupPropertiesSize; i++){
        UA_KeyValuePair_deleteMembers(&writerGroupConfig->groupProperties[i]);
    }
    UA_free(writerGroupConfig->groupProperties);
}

void
UA_WriterGroup_deleteMembers(UA_Server *server, UA_WriterGroup *writerGroup) {
    UA_WriterGroupConfig_deleteMembers(&writerGroup->config);
    //delete WriterGroup
    //delete all writers. Therefore removeDataSetWriter is called from PublishedDataSet
    UA_DataSetWriter *dataSetWriter, *tmpDataSetWriter;
    LIST_FOREACH_SAFE(dataSetWriter, &writerGroup->writers, listEntry, tmpDataSetWriter){
        UA_Server_removeDataSetWriter(server, dataSetWriter->identifier);
    }
    LIST_REMOVE(writerGroup, listEntry);
    UA_NodeId_deleteMembers(&writerGroup->linkedConnection);
    UA_NodeId_deleteMembers(&writerGroup->identifier);
}

UA_StatusCode
UA_Server_addDataSetWriter(UA_Server *server,
                           const UA_NodeId writerGroup, const UA_NodeId dataSet,
                           const UA_DataSetWriterConfig *dataSetWriterConfig,
                           UA_NodeId *writerIdentifier) {
    UA_StatusCode retVal = UA_STATUSCODE_GOOD;
    if(!dataSetWriterConfig)
        return UA_STATUSCODE_BADINVALIDARGUMENT;

    UA_PublishedDataSet *currentDataSetContext = UA_PublishedDataSet_findPDSbyId(server, dataSet);
    if(!currentDataSetContext)
        return UA_STATUSCODE_BADNOTFOUND;

    UA_WriterGroup *wg = UA_WriterGroup_findWGbyId(server, writerGroup);
    if(!wg)
        return UA_STATUSCODE_BADNOTFOUND;

    UA_DataSetWriter *newDataSetWriter = (UA_DataSetWriter *) UA_calloc(1, sizeof(UA_DataSetWriter));
    if(!newDataSetWriter)
        return UA_STATUSCODE_BADOUTOFMEMORY;

    //copy the config into the new dataSetWriter
    UA_DataSetWriterConfig tmpDataSetWriterConfig;
    retVal |= UA_DataSetWriterConfig_copy(dataSetWriterConfig, &tmpDataSetWriterConfig);
    newDataSetWriter->config = tmpDataSetWriterConfig;
    //save the current version of the connected PublishedDataSet
    newDataSetWriter->connectedDataSetVersion = currentDataSetContext->dataSetMetaData.configurationVersion;
    //initialize the queue for the last values
    newDataSetWriter->lastSamplesCount = currentDataSetContext->fieldSize;
    newDataSetWriter->lastSamples = (UA_DataSetWriterSample * )
        UA_calloc(newDataSetWriter->lastSamplesCount, sizeof(UA_DataSetWriterSample));
    if(!newDataSetWriter->lastSamples) {
        UA_DataSetWriterConfig_deleteMembers(&newDataSetWriter->config);
        UA_free(newDataSetWriter);
        return UA_STATUSCODE_BADOUTOFMEMORY;
    }
    for(size_t i = 0; i < newDataSetWriter->lastSamplesCount; i++) {
        newDataSetWriter->lastSamples[i].value = (UA_DataValue *) UA_calloc(1, sizeof(UA_DataValue));
        if(!newDataSetWriter->lastSamples[i].value) {
            for(size_t j = 0; j < i; j++)
                UA_free(newDataSetWriter->lastSamples[j].value);
            UA_DataSetWriterConfig_deleteMembers(&newDataSetWriter->config);
            UA_free(newDataSetWriter);
            return UA_STATUSCODE_BADOUTOFMEMORY;
        }
    }
    //connect PublishedDataSet with DataSetWriter
    newDataSetWriter->connectedDataSet = currentDataSetContext->identifier;
    newDataSetWriter->linkedWriterGroup = wg->identifier;
    UA_PubSubManager_generateUniqueNodeId(server, &newDataSetWriter->identifier);
    if(writerIdentifier != NULL)
        UA_NodeId_copy(&newDataSetWriter->identifier, writerIdentifier);
    //add the new writer to the group
    LIST_INSERT_HEAD(&wg->writers, newDataSetWriter, listEntry);
    wg->writersCount++;
#ifdef UA_ENABLE_PUBSUB_INFORMATIONMODEL
    addDataSetWriterRepresentation(server, newDataSetWriter);
#endif
    return retVal;
}

UA_StatusCode
UA_Server_removeDataSetWriter(UA_Server *server, const UA_NodeId dsw){
    UA_DataSetWriter *dataSetWriter = UA_DataSetWriter_findDSWbyId(server, dsw);
    if(!dataSetWriter)
        return UA_STATUSCODE_BADNOTFOUND;

    UA_WriterGroup *linkedWriterGroup = UA_WriterGroup_findWGbyId(server, dataSetWriter->linkedWriterGroup);
    if(!linkedWriterGroup)
        return UA_STATUSCODE_BADNOTFOUND;

    linkedWriterGroup->writersCount--;
#ifdef UA_ENABLE_PUBSUB_INFORMATIONMODEL
    removeDataSetWriterRepresentation(server, dataSetWriter);
#endif
    //remove DataSetWriter from group
    UA_DataSetWriter_deleteMembers(server, dataSetWriter);
    UA_free(dataSetWriter);
    return UA_STATUSCODE_GOOD;
}

/**********************************************/
/*                DataSetField                */
/**********************************************/

UA_StatusCode
UA_DataSetFieldConfig_copy(const UA_DataSetFieldConfig *src, UA_DataSetFieldConfig *dst){
    memcpy(dst, src, sizeof(UA_DataSetFieldConfig));
    if(src->dataSetFieldType == UA_PUBSUB_DATASETFIELD_VARIABLE) {
        UA_String_copy(&src->field.variable.fieldNameAlias, &dst->field.variable.fieldNameAlias);
        UA_PublishedVariableDataType_copy(&src->field.variable.publishParameters,
                                          &dst->field.variable.publishParameters);
    } else {
        return UA_STATUSCODE_BADNOTSUPPORTED;
    }

    return UA_STATUSCODE_GOOD;
}

UA_StatusCode
UA_Server_getDataSetFieldConfig(UA_Server *server, const UA_NodeId dsf,
                                UA_DataSetFieldConfig *config) {
    UA_StatusCode retVal = UA_STATUSCODE_GOOD;
    if(!config)
        return UA_STATUSCODE_BADINVALIDARGUMENT;
    UA_DataSetField *currentDataSetField = UA_DataSetField_findDSFbyId(server, dsf);
    if(!currentDataSetField)
        return UA_STATUSCODE_BADNOTFOUND;
    UA_DataSetFieldConfig tmpFieldConfig;
    //deep copy of the actual config
    retVal |= UA_DataSetFieldConfig_copy(&currentDataSetField->config, &tmpFieldConfig);
    *config = tmpFieldConfig;
    return retVal;
}

UA_DataSetField *
UA_DataSetField_findDSFbyId(UA_Server *server, UA_NodeId identifier) {
    for(size_t i = 0; i < server->pubSubManager.publishedDataSetsSize; i++){
        UA_DataSetField *tmpField;
        LIST_FOREACH(tmpField, &server->pubSubManager.publishedDataSets[i].fields, listEntry){
            if(UA_NodeId_equal(&tmpField->identifier, &identifier)){
                return tmpField;
            }
        }
    }
    return NULL;
}

void
UA_DataSetFieldConfig_deleteMembers(UA_DataSetFieldConfig *dataSetFieldConfig){
    if(dataSetFieldConfig->dataSetFieldType == UA_PUBSUB_DATASETFIELD_VARIABLE){
        UA_String_deleteMembers(&dataSetFieldConfig->field.variable.fieldNameAlias);
        UA_PublishedVariableDataType_deleteMembers(&dataSetFieldConfig->field.variable.publishParameters);
    }
}

void UA_DataSetField_deleteMembers(UA_DataSetField *field) {
    UA_DataSetFieldConfig_deleteMembers(&field->config);
    //delete DataSetField
    UA_NodeId_deleteMembers(&field->identifier);
    UA_NodeId_deleteMembers(&field->publishedDataSet);
    UA_FieldMetaData_deleteMembers(&field->fieldMetaData);
    UA_DataValue_deleteMembers(&field->lastValue);
    LIST_REMOVE(field, listEntry);
}

/*********************************************************/
/*               PublishValues handling                  */
/*********************************************************/

/**
 * Compare two variants. Internally used for value change detection.
 *
 * @return UA_TRUE if the value has changed
 */
static UA_Boolean
valueChangedVariant(UA_Variant *oldValue, UA_Variant *newValue){
    if(! (oldValue && newValue))
        return UA_FALSE;

    UA_ByteString *oldValueEncoding = UA_ByteString_new(), *newValueEncoding = UA_ByteString_new();
    size_t oldValueEncodingSize, newValueEncodingSize;
    oldValueEncodingSize = UA_calcSizeBinary(oldValue, &UA_TYPES[UA_TYPES_VARIANT]);
    newValueEncodingSize = UA_calcSizeBinary(newValue, &UA_TYPES[UA_TYPES_VARIANT]);
    if((oldValueEncodingSize == 0) || (newValueEncodingSize == 0))
        return UA_FALSE;

    if(oldValueEncodingSize != newValueEncodingSize)
        return UA_TRUE;

    if(UA_ByteString_allocBuffer(oldValueEncoding, oldValueEncodingSize) != UA_STATUSCODE_GOOD)
        return UA_FALSE;

    if(UA_ByteString_allocBuffer(newValueEncoding, newValueEncodingSize) != UA_STATUSCODE_GOOD)
        return UA_FALSE;

    UA_Byte *bufPosOldValue = oldValueEncoding->data;
    const UA_Byte *bufEndOldValue = &oldValueEncoding->data[oldValueEncoding->length];
    UA_Byte *bufPosNewValue = newValueEncoding->data;
    const UA_Byte *bufEndNewValue = &newValueEncoding->data[newValueEncoding->length];
    if(UA_encodeBinary(oldValue, &UA_TYPES[UA_TYPES_VARIANT],
                       &bufPosOldValue, &bufEndOldValue, NULL, NULL) != UA_STATUSCODE_GOOD){
        return UA_FALSE;
    }
    if(UA_encodeBinary(newValue, &UA_TYPES[UA_TYPES_VARIANT],
                       &bufPosNewValue, &bufEndNewValue, NULL, NULL) != UA_STATUSCODE_GOOD){
        return UA_FALSE;
    }
    oldValueEncoding->length = (uintptr_t)bufPosOldValue - (uintptr_t)oldValueEncoding->data;
    newValueEncoding->length = (uintptr_t)bufPosNewValue - (uintptr_t)newValueEncoding->data;
    UA_Boolean compareResult = !UA_ByteString_equal(oldValueEncoding, newValueEncoding);
    UA_ByteString_delete(oldValueEncoding);
    UA_ByteString_delete(newValueEncoding);
    return compareResult;
}

/**
 * Obtain the latest value for a specific DataSetField. This method is currently
 * called inside the DataSetMessage generation process.
 */
static UA_StatusCode
UA_PubSubDataSetField_sampleValue(UA_Server *server, UA_DataSetField *field) {
    /* Read the value */
    UA_ReadValueId rvid;
    UA_ReadValueId_init(&rvid);
    rvid.nodeId = field->config.field.variable.publishParameters.publishedVariable;
    rvid.attributeId = field->config.field.variable.publishParameters.attributeId;
    rvid.indexRange = field->config.field.variable.publishParameters.indexRange;
    UA_DataValue value = UA_Server_read(server, &rvid, UA_TIMESTAMPSTORETURN_BOTH);
    UA_DataValue_deleteMembers(&field->lastValue);
    field->lastValue = value;
    return UA_STATUSCODE_GOOD;
}

static UA_StatusCode
UA_PubSubDataSetWriter_generateKeyFrameMessage(UA_Server *server, UA_DataSetMessage *dataSetMessage,
                                               UA_DataSetWriter *dataSetWriter) {
    UA_PublishedDataSet *currentDataSet = UA_PublishedDataSet_findPDSbyId(server, dataSetWriter->connectedDataSet);
    if(!currentDataSet)
        return UA_STATUSCODE_BADNOTFOUND;
    //prepare DataSetMessageContent
    dataSetMessage->header.dataSetMessageValid = true;
    dataSetMessage->header.dataSetMessageType = UA_DATASETMESSAGE_DATAKEYFRAME;
    dataSetMessage->data.keyFrameData.fieldCount = currentDataSet->fieldSize;
    dataSetMessage->data.keyFrameData.dataSetFields = (UA_DataValue *)
            UA_Array_new(currentDataSet->fieldSize, &UA_TYPES[UA_TYPES_DATAVALUE]);
    if(!dataSetMessage->data.keyFrameData.dataSetFields)
        return UA_STATUSCODE_BADOUTOFMEMORY;

    UA_DataSetField *tmpDataSetField;
    size_t counter = 0;
    LIST_FOREACH(tmpDataSetField, &currentDataSet->fields, listEntry){
        if(UA_PubSubDataSetField_sampleValue(server, tmpDataSetField) == UA_STATUSCODE_GOOD){
            //include field into DSM
            UA_DataValue_init(&dataSetMessage->data.keyFrameData.dataSetFields[counter]);
            UA_DataValue_copy(&tmpDataSetField->lastValue, &dataSetMessage->data.keyFrameData.dataSetFields[counter]);
            if((dataSetWriter->config.dataSetFieldContentMask & (unsigned int) UA_DATASETFIELDCONTENTMASK_STATUSCODE) == 0){
                dataSetMessage->data.keyFrameData.dataSetFields[counter].hasStatus = UA_FALSE;
            }
            if((dataSetWriter->config.dataSetFieldContentMask & (unsigned int) UA_DATASETFIELDCONTENTMASK_SOURCETIMESTAMP) == 0){
                dataSetMessage->data.keyFrameData.dataSetFields[counter].hasSourceTimestamp = UA_FALSE;
                if((dataSetWriter->config.dataSetFieldContentMask & (unsigned int) UA_DATASETFIELDCONTENTMASK_SOURCEPICOSECONDS) == 0){
                    dataSetMessage->data.keyFrameData.dataSetFields[counter].hasServerPicoseconds = UA_FALSE;
                }
            }
            if((dataSetWriter->config.dataSetFieldContentMask & (unsigned int) UA_DATASETFIELDCONTENTMASK_SERVERTIMESTAMP) == 0){
                dataSetMessage->data.keyFrameData.dataSetFields[counter].hasServerTimestamp = UA_FALSE;
            }
            //Update lastValue store
            UA_DataValue_deleteMembers(dataSetWriter->lastSamples[counter].value);
            UA_DataValue_copy(&tmpDataSetField->lastValue, dataSetWriter->lastSamples[counter++].value);
        }
    }
    return UA_STATUSCODE_GOOD;
}

static UA_StatusCode
UA_PubSubDataSetWriter_generateDeltaFrameMessage(UA_Server *server, UA_DataSetMessage *dataSetMessage,
                                                 UA_DataSetWriter *dataSetWriter) {
    UA_PublishedDataSet *currentDataSet = UA_PublishedDataSet_findPDSbyId(server, dataSetWriter->connectedDataSet);
    if(!currentDataSet)
        return UA_STATUSCODE_BADNOTFOUND;
    //prepare DataSetMessageContent
    memset(dataSetMessage, 0, sizeof(UA_DataSetMessage));
    dataSetMessage->header.dataSetMessageValid = true;
    dataSetMessage->header.dataSetMessageType = UA_DATASETMESSAGE_DATADELTAFRAME;
    UA_DataSetField *tmpDataSetField;
    size_t counter = 0;
    LIST_FOREACH(tmpDataSetField, &currentDataSet->fields, listEntry) {
        if(UA_PubSubDataSetField_sampleValue(server, tmpDataSetField) == UA_STATUSCODE_GOOD) {
            //check if the value has changed
            if(valueChangedVariant(&dataSetWriter->lastSamples[counter].value->value, &tmpDataSetField->lastValue.value)){
                //increase fieldCount for current delta message
                dataSetMessage->data.deltaFrameData.fieldCount++;
                dataSetWriter->lastSamples[counter].valeChanged = UA_TRUE;
            } else {
                dataSetWriter->lastSamples[counter].valeChanged = UA_FALSE;
            }
            //update last stored sample
            UA_DataValue_init(dataSetWriter->lastSamples[counter].value);
            UA_DataValue_copy(&tmpDataSetField->lastValue, dataSetWriter->lastSamples[counter++].value);
        }
    }
    //allocate DeltaFrameFields
    UA_DataSetMessage_DeltaFrameField * deltaFields = (UA_DataSetMessage_DeltaFrameField *)
            UA_calloc(dataSetMessage->data.deltaFrameData.fieldCount, sizeof(UA_DataSetMessage_DeltaFrameField));
    if(!deltaFields)
        return UA_STATUSCODE_BADOUTOFMEMORY;

    dataSetMessage->data.deltaFrameData.deltaFrameFields = deltaFields;
    size_t currentDeltaField = 0;
    for(size_t i = 0; i < currentDataSet->fieldSize; i++){
        if(dataSetWriter->lastSamples[i].valeChanged){
            deltaFields[currentDeltaField].fieldIndex = (UA_UInt16) i;
            UA_DataValue_copy(dataSetWriter->lastSamples[i].value, &deltaFields[currentDeltaField].fieldValue);
            dataSetWriter->lastSamples[i].valeChanged = false;
            if((dataSetWriter->config.dataSetFieldContentMask & (unsigned int) UA_DATASETFIELDCONTENTMASK_STATUSCODE) == 0){
                dataSetMessage->data.deltaFrameData.deltaFrameFields[currentDeltaField].fieldValue.hasStatus = UA_FALSE;
            }
            if((dataSetWriter->config.dataSetFieldContentMask & (unsigned int) UA_DATASETFIELDCONTENTMASK_SOURCETIMESTAMP) == 0){
                dataSetMessage->data.deltaFrameData.deltaFrameFields[currentDeltaField].fieldValue.hasSourceTimestamp = UA_FALSE;
                if((dataSetWriter->config.dataSetFieldContentMask & (unsigned int) UA_DATASETFIELDCONTENTMASK_SOURCEPICOSECONDS) == 0){
                    dataSetMessage->data.deltaFrameData.deltaFrameFields[currentDeltaField].fieldValue.hasServerPicoseconds = UA_FALSE;
                }
            }
            if((dataSetWriter->config.dataSetFieldContentMask & (unsigned int) UA_DATASETFIELDCONTENTMASK_SERVERTIMESTAMP) == 0){
                dataSetMessage->data.deltaFrameData.deltaFrameFields[currentDeltaField].fieldValue.hasServerTimestamp = UA_FALSE;
            }
            currentDeltaField++;
        }
    }
    return UA_STATUSCODE_GOOD;
}

/**
 * Generate a DataSetMessage for the given writer.
 *
 * @param dataSetWriter ptr to corresponding writer
 * @return ptr to generated DataSetMessage
 */
static UA_StatusCode
UA_DataSetWriter_generateDataSetMessage(UA_Server *server, UA_DataSetMessage *dataSetMessage,
                                        UA_DataSetWriter *dataSetWriter) {
    UA_PublishedDataSet *currentDataSet = UA_PublishedDataSet_findPDSbyId(server, dataSetWriter->connectedDataSet);
    if(!currentDataSet)
        return UA_STATUSCODE_BADNOTFOUND;
    memset(dataSetMessage, 0, sizeof(UA_DataSetMessage));
    //currently is only UADP supported. The configuration Flags are included inside the std. defined UA_UadpDataSetWriterMessageDataType
    UA_UadpDataSetWriterMessageDataType *dataSetWriterMessageDataType = NULL;
    if((dataSetWriter->config.messageSettings.encoding == UA_EXTENSIONOBJECT_DECODED ||
        dataSetWriter->config.messageSettings.encoding == UA_EXTENSIONOBJECT_DECODED_NODELETE) &&
       (dataSetWriter->config.messageSettings.content.decoded.type == &UA_TYPES[UA_TYPES_UADPDATASETWRITERMESSAGEDATATYPE])) {
        dataSetWriterMessageDataType = (UA_UadpDataSetWriterMessageDataType *) dataSetWriter->config.messageSettings.content.decoded.data;
    } else {
        //create default flag configuration if no UadpDataSetWriterMessageDataType was passed in
        UA_UadpDataSetWriterMessageDataType defaultUadpConfiguration;
        memset(&defaultUadpConfiguration, 0, sizeof(UA_UadpDataSetWriterMessageDataType));
        defaultUadpConfiguration.dataSetMessageContentMask = (UA_UadpDataSetMessageContentMask) ((unsigned int) UA_UADPDATASETMESSAGECONTENTMASK_TIMESTAMP |
                                                                                                 (unsigned int) UA_UADPDATASETMESSAGECONTENTMASK_MAJORVERSION |
                                                                                                 (unsigned int) UA_UADPDATASETMESSAGECONTENTMASK_MINORVERSION);
        dataSetWriterMessageDataType = &defaultUadpConfiguration;
    }
    if(dataSetWriterMessageDataType->networkMessageNumber != 0 || dataSetWriterMessageDataType->dataSetOffset != 0 ||
       dataSetWriterMessageDataType->configuredSize !=0 ){
        UA_LOG_WARNING(server->config.logger, UA_LOGCATEGORY_SERVER, "Static DSM configuration not supported. Using defaults");
        dataSetWriterMessageDataType->networkMessageNumber = 0;
        dataSetWriterMessageDataType->dataSetOffset = 0;
        dataSetWriterMessageDataType->configuredSize = 0;
    }
    //The encoding depends on the flags inside the writer config.
    if(dataSetWriter->config.dataSetFieldContentMask & (unsigned int) UA_DATASETFIELDCONTENTMASK_RAWDATAENCODING) {
        dataSetMessage->header.fieldEncoding = UA_FIELDENCODING_RAWDATA;
    } else if (dataSetWriter->config.dataSetFieldContentMask &
               ((unsigned  int) UA_DATASETFIELDCONTENTMASK_SOURCETIMESTAMP |
                (unsigned  int) UA_DATASETFIELDCONTENTMASK_SERVERPICOSECONDS |
                (unsigned  int) UA_DATASETFIELDCONTENTMASK_SOURCEPICOSECONDS |
                (unsigned  int) UA_DATASETFIELDCONTENTMASK_STATUSCODE)) {
        dataSetMessage->header.fieldEncoding = UA_FIELDENCODING_DATAVALUE;
    } else {
        dataSetMessage->header.fieldEncoding = UA_FIELDENCODING_VARIANT;
    }
    //Std: 'The DataSetMessageContentMask defines the flags for the content of the DataSetMessage header.'
    if(dataSetWriterMessageDataType->dataSetMessageContentMask & (unsigned int) UA_UADPDATASETMESSAGECONTENTMASK_MAJORVERSION){
        dataSetMessage->header.configVersionMajorVersionEnabled = UA_TRUE;
        dataSetMessage->header.configVersionMajorVersion = currentDataSet->dataSetMetaData.configurationVersion.majorVersion;
    }
    if(dataSetWriterMessageDataType->dataSetMessageContentMask & (unsigned int) UA_UADPDATASETMESSAGECONTENTMASK_MINORVERSION){
        dataSetMessage->header.configVersionMinorVersionEnabled = UA_TRUE;
        dataSetMessage->header.configVersionMinorVersion = currentDataSet->dataSetMetaData.configurationVersion.minorVersion;
    }
    if(dataSetWriterMessageDataType->dataSetMessageContentMask & (unsigned int) UA_UADPDATASETMESSAGECONTENTMASK_SEQUENCENUMBER) {
        dataSetMessage->header.dataSetMessageSequenceNrEnabled = UA_TRUE;
        dataSetMessage->header.dataSetMessageSequenceNr = dataSetWriter->actualDataSetMessageSequenceCount;
    }
    if(dataSetWriterMessageDataType->dataSetMessageContentMask & (unsigned int) UA_UADPDATASETMESSAGECONTENTMASK_TIMESTAMP) {
        dataSetMessage->header.timestampEnabled = UA_TRUE;
        dataSetMessage->header.timestamp = UA_DateTime_now();
        if(dataSetWriterMessageDataType->dataSetMessageContentMask & (unsigned int) UA_UADPDATASETMESSAGECONTENTMASK_PICOSECONDS) {
            dataSetMessage->header.picoSecondsIncluded = UA_FALSE;
            UA_LOG_WARNING(server->config.logger, UA_LOGCATEGORY_SERVER, "DSM picosecond field is currently not supported. Using defaults");
        }
    }
    if(dataSetWriterMessageDataType->dataSetMessageContentMask & (unsigned int) UA_UADPDATASETMESSAGECONTENTMASK_STATUS){
        dataSetMessage->header.statusEnabled = UA_FALSE;
        UA_LOG_WARNING(server->config.logger, UA_LOGCATEGORY_SERVER, "DSM status field is currently not supported. Using defaults");
    }
    if(dataSetWriter->actualDataSetMessageSequenceCount < UA_UINT16_MAX){
        dataSetWriter->actualDataSetMessageSequenceCount++;
    } else {
        dataSetWriter->actualDataSetMessageSequenceCount = 0;
    }
    //check if the PublishedDataSet version has changed -> if yes flush the lastValue store and send a KeyFrame.
    if(dataSetWriter->connectedDataSetVersion.majorVersion != currentDataSet->dataSetMetaData.configurationVersion.majorVersion ||
       dataSetWriter->connectedDataSetVersion.minorVersion != currentDataSet->dataSetMetaData.configurationVersion.minorVersion) {

        //realloc pds dependent memory
        dataSetWriter->lastSamplesCount = currentDataSet->fieldSize;
        dataSetWriter->lastSamples = (UA_DataSetWriterSample * ) UA_realloc(dataSetWriter->lastSamples,
                                                                            sizeof(UA_DataSetWriterSample) * dataSetWriter->lastSamplesCount);
        if(!dataSetWriter->lastSamples)
            return UA_STATUSCODE_BADOUTOFMEMORY;

        for (size_t i = 0; i < dataSetWriter->lastSamplesCount; i++) {
            dataSetWriter->lastSamples[i].value = (UA_DataValue *) UA_calloc(1, sizeof(UA_DataValue));
            if(!dataSetWriter->lastSamples[i].value)
                return UA_STATUSCODE_BADOUTOFMEMORY;
        }
        dataSetWriter->connectedDataSetVersion = currentDataSet->dataSetMetaData.configurationVersion;
        UA_PubSubDataSetWriter_generateKeyFrameMessage(server, dataSetMessage, dataSetWriter);
        dataSetWriter->deltaFrameCounter = 0;
    } else if (currentDataSet->fieldSize == 1 || dataSetWriter->deltaFrameCounter == 0 || dataSetWriter->deltaFrameCounter > dataSetWriter->config.keyFrameCount){
        //@info the standard defines: if a PDS contains only one fields no delta messages should be generated
        //because they need more memory than a keyframe with 1 field.
        UA_PubSubDataSetWriter_generateKeyFrameMessage(server, dataSetMessage, dataSetWriter);
        dataSetWriter->deltaFrameCounter = 1;
    } else {
        UA_PubSubDataSetWriter_generateDeltaFrameMessage(server, dataSetMessage, dataSetWriter);
        dataSetWriter->deltaFrameCounter++;
    }
    return UA_STATUSCODE_GOOD;
}

/*
 * This callback triggers the collection and publish of NetworkMessages and the contained DataSetMessages.
 */
void
UA_WriterGroup_publishCallback(UA_Server *server, UA_WriterGroup *writerGroup) {
    if(!writerGroup){
        UA_LOG_ERROR(server->config.logger, UA_LOGCATEGORY_SERVER, "Publish failed. WriterGroup not found");
        return;
    }
    if(writerGroup->writersCount <= 0)
        return;

    if(writerGroup->config.encodingMimeType != UA_PUBSUB_ENCODING_UADP) {
        UA_LOG_ERROR(server->config.logger, UA_LOGCATEGORY_SERVER, "Unknown encoding type.");
        return;
    }
    //prevent error if the maxEncapsulatedDataSetMessageCount is set to 0->1
    writerGroup->config.maxEncapsulatedDataSetMessageCount = (UA_UInt16) (writerGroup->config.maxEncapsulatedDataSetMessageCount == 0 ||
                                                                          writerGroup->config.maxEncapsulatedDataSetMessageCount > UA_BYTE_MAX
                                                                          ? 1 : writerGroup->config.maxEncapsulatedDataSetMessageCount);

    UA_DataSetMessage *dsmStore = (UA_DataSetMessage *) UA_calloc(writerGroup->writersCount, sizeof(UA_DataSetMessage));
    if(!dsmStore) {
        UA_LOG_ERROR(server->config.logger, UA_LOGCATEGORY_SERVER, "DataSetMessage allocation failed");
        return;
    }
    memset(dsmStore, 0, sizeof(UA_DataSetMessage) * writerGroup->writersCount);
    //The binary DataSetMessage sizes are part of the payload. Memory is allocated on the stack.
    UA_STACKARRAY(UA_UInt16, dsmSizes, writerGroup->writersCount);
    memset(dsmSizes, 0, writerGroup->writersCount * sizeof(UA_UInt16));
    /*
     * Calculate the number of needed NetworkMessages. The previous allocated DataSetMessage array is
     * filled from left for combined DSM messages and from the right for single DSM.
     *     Allocated DSM Array
     *    +----------------------------+
     *    |DSM1||DSM2||DSM3||DSM4||DSM5|
     *    +--+----+-----+-----+-----+--+
     *       |    |     |     |     |
     *       |    |     |     |     |
     *    +--v----v-----v-----v--+--v--+
     *    |    NM1        || NM2 | NM3 |
     *    +----------------------+-----+
     *    NetworkMessages
     */
    UA_UInt16 combinedNetworkMessageCount = 0, singleNetworkMessagesCount = 0;
    UA_DataSetWriter *tmpDataSetWriter;
    LIST_FOREACH(tmpDataSetWriter, &writerGroup->writers, listEntry){
        //if promoted fields are contained in the PublishedDataSet, then this DSM must encapsulated in one NM
        UA_PublishedDataSet *tmpPublishedDataSet = UA_PublishedDataSet_findPDSbyId(server, tmpDataSetWriter->connectedDataSet);
        if(!tmpPublishedDataSet) {
            UA_LOG_ERROR(server->config.logger, UA_LOGCATEGORY_SERVER, "Publish failed. PublishedDataSet not found");
            return;
        }
        if(tmpPublishedDataSet->promotedFieldsCount > 0) {
            if(UA_DataSetWriter_generateDataSetMessage(server, &dsmStore[(writerGroup->writersCount - 1) - singleNetworkMessagesCount],
                                                       tmpDataSetWriter) != UA_STATUSCODE_GOOD){
                UA_LOG_ERROR(server->config.logger, UA_LOGCATEGORY_SERVER, "Publish failed. DataSetMessage creation failed");
                return;
            };
            dsmSizes[(writerGroup->writersCount-1) - singleNetworkMessagesCount] = (UA_UInt16) UA_DataSetMessage_calcSizeBinary(&dsmStore[(writerGroup->writersCount-1)
                                                                                                                                          - singleNetworkMessagesCount]);
            singleNetworkMessagesCount++;
        } else {
            if(UA_DataSetWriter_generateDataSetMessage(server, &dsmStore[combinedNetworkMessageCount], tmpDataSetWriter) != UA_STATUSCODE_GOOD){
                UA_LOG_ERROR(server->config.logger, UA_LOGCATEGORY_SERVER, "Publish failed. DataSetMessage creation failed");
                return;
            };
            dsmSizes[combinedNetworkMessageCount] = (UA_UInt16) UA_DataSetMessage_calcSizeBinary(&dsmStore[combinedNetworkMessageCount]);
            combinedNetworkMessageCount++;
        }
    }
    UA_UInt32 networkMessageCount = singleNetworkMessagesCount;
    if(combinedNetworkMessageCount != 0){
        combinedNetworkMessageCount = (UA_UInt16) (
                combinedNetworkMessageCount / writerGroup->config.maxEncapsulatedDataSetMessageCount +
                (combinedNetworkMessageCount % writerGroup->config.maxEncapsulatedDataSetMessageCount) == 0 ? 0 : 1);
        networkMessageCount += combinedNetworkMessageCount;
    }
    //Alloc memory for the NetworkMessages on the stack
    UA_STACKARRAY(UA_NetworkMessage, nmStore, networkMessageCount);
    memset(nmStore, 0, networkMessageCount * sizeof(UA_NetworkMessage));
    UA_UInt32 currentDSMPosition = 0;
    for(UA_UInt32 i = 0; i < networkMessageCount; i++) {
        nmStore[i].version = 1;
        nmStore[i].networkMessageType = UA_NETWORKMESSAGE_DATASET;
        //create combined NetworkMessages
        if(i < (networkMessageCount-singleNetworkMessagesCount)){
            if(combinedNetworkMessageCount - (i * writerGroup->config.maxEncapsulatedDataSetMessageCount)){
                if(combinedNetworkMessageCount == 1){
                    nmStore[i].payloadHeader.dataSetPayloadHeader.count = (UA_Byte) ((writerGroup->writersCount) - singleNetworkMessagesCount);
                    currentDSMPosition = 0;
                } else {
                    nmStore[i].payloadHeader.dataSetPayloadHeader.count = (UA_Byte) writerGroup->config.maxEncapsulatedDataSetMessageCount;
                    currentDSMPosition = i * writerGroup->config.maxEncapsulatedDataSetMessageCount;
                }
                //nmStore[i].payloadHeader.dataSetPayloadHeader.count = (UA_Byte) writerGroup->config.maxEncapsulatedDataSetMessageCount;
                nmStore[i].payload.dataSetPayload.dataSetMessages = &dsmStore[currentDSMPosition];
                nmStore->payload.dataSetPayload.sizes = &dsmSizes[currentDSMPosition];
            } else {
                currentDSMPosition = i * writerGroup->config.maxEncapsulatedDataSetMessageCount;
                nmStore[i].payloadHeader.dataSetPayloadHeader.count = (UA_Byte) (currentDSMPosition - ((i - 1) * writerGroup->config.maxEncapsulatedDataSetMessageCount)); //attention cast from uint32 to byte
                nmStore[i].payload.dataSetPayload.dataSetMessages = &dsmStore[currentDSMPosition];
                nmStore->payload.dataSetPayload.sizes = &dsmSizes[currentDSMPosition];
            }
        } else {///create single NetworkMessages (1 DSM per NM)
            nmStore[i].payloadHeader.dataSetPayloadHeader.count = 1;
            currentDSMPosition = (UA_UInt32) combinedNetworkMessageCount + (i - combinedNetworkMessageCount/writerGroup->config.maxEncapsulatedDataSetMessageCount
                                                                            + (combinedNetworkMessageCount % writerGroup->config.maxEncapsulatedDataSetMessageCount) == 0 ? 0 : 1);
            nmStore[i].payload.dataSetPayload.dataSetMessages = &dsmStore[currentDSMPosition];
            nmStore->payload.dataSetPayload.sizes = &dsmSizes[currentDSMPosition];
        }
        UA_PubSubConnection *connection = UA_PubSubConnection_findConnectionbyId(server, writerGroup->linkedConnection);
        if(!connection){
            UA_LOG_ERROR(server->config.logger, UA_LOGCATEGORY_SERVER, "Publish failed. PubSubConnection invalid.");
            return;
        }
        //send the prepared messages
        UA_ByteString buf;
        size_t msgSize = UA_NetworkMessage_calcSizeBinary(&nmStore[i]);
        if(UA_ByteString_allocBuffer(&buf, msgSize) == UA_STATUSCODE_GOOD) {
            UA_Byte *bufPos = buf.data;
            memset(bufPos, 0, msgSize);
            const UA_Byte *bufEnd = &(buf.data[buf.length]);
            if(UA_NetworkMessage_encodeBinary(&nmStore[i], &bufPos, bufEnd) != UA_STATUSCODE_GOOD){
                UA_ByteString_deleteMembers(&buf);
                return;
            };
            connection->channel->send(connection->channel, NULL, &buf);
        }
        nmStore[i].payloadHeaderEnabled = UA_TRUE;
        //The stack allocated sizes field must be set to NULL to prevent invalid free.
        nmStore[i].payload.dataSetPayload.sizes = NULL;
        UA_ByteString_deleteMembers(&buf);
        UA_NetworkMessage_deleteMembers(&nmStore[i]);
    }
}

/*
 * Add new publishCallback. The first execution is triggered directly after creation.
 * @Warning - The duration (double) is currently casted to int. -> intervals smaller 1ms are not possible.
 */
UA_StatusCode
UA_WriterGroup_addPublishCallback(UA_Server *server, UA_WriterGroup *writerGroup) {
    UA_StatusCode retval =
            UA_PubSubManager_addRepeatedCallback(server, (UA_ServerCallback) UA_WriterGroup_publishCallback,
                                                 writerGroup, (UA_UInt32) writerGroup->config.publishingInterval,
                                                 &writerGroup->publishCallbackId);
    if(retval == UA_STATUSCODE_GOOD)
        writerGroup->publishCallbackIsRegistered = true;
    //run once after creation
    UA_WriterGroup_publishCallback(server, writerGroup);
    return retval;
}

#endif /* UA_ENABLE_PUBSUB */