open62541/src/server/ua_subscription.c

#include "ua_subscription.h"
#include "ua_server_internal.h"
#include "ua_types_encoding_binary.h"
#include "ua_services.h"
#include "ua_nodestore.h"

#ifdef UA_ENABLE_SUBSCRIPTIONS /* conditional compilation */

#define UA_VALUENCODING_MAXSTACK 512

/*****************/
/* MonitoredItem */
/*****************/

UA_MonitoredItem * UA_MonitoredItem_new() {
    UA_MonitoredItem *new = UA_malloc(sizeof(UA_MonitoredItem));
    new->subscription = NULL;
    new->currentQueueSize = 0;
    new->maxQueueSize = 0;
    new->monitoredItemType = UA_MONITOREDITEMTYPE_CHANGENOTIFY; /* currently hardcoded */
    new->timestampsToReturn = UA_TIMESTAMPSTORETURN_SOURCE;
    UA_String_init(&new->indexRange);
    TAILQ_INIT(&new->queue);
    UA_NodeId_init(&new->monitoredNodeId);
    new->lastSampledValue = UA_BYTESTRING_NULL;
    memset(&new->sampleJobGuid, 0, sizeof(UA_Guid));
    new->sampleJobIsRegistered = false;
    new->itemId = 0;
    return new;
}

void MonitoredItem_delete(UA_Server *server, UA_MonitoredItem *monitoredItem) {
    MonitoredItem_unregisterSampleJob(server, monitoredItem);
    /* clear the queued samples */
    MonitoredItem_queuedValue *val, *val_tmp;
    TAILQ_FOREACH_SAFE(val, &monitoredItem->queue, listEntry, val_tmp) {
        TAILQ_REMOVE(&monitoredItem->queue, val, listEntry);
        UA_DataValue_deleteMembers(&val->value);
        UA_free(val);
    }
    monitoredItem->currentQueueSize = 0;
    LIST_REMOVE(monitoredItem, listEntry);
    UA_String_deleteMembers(&monitoredItem->indexRange);
    UA_ByteString_deleteMembers(&monitoredItem->lastSampledValue);
    UA_NodeId_deleteMembers(&monitoredItem->monitoredNodeId);
    UA_free(monitoredItem);
}

static void
ensureSpaceInMonitoredItemQueue(UA_MonitoredItem *mon) {
    if(mon->currentQueueSize < mon->maxQueueSize)
        return;
    MonitoredItem_queuedValue *queueItem;
    if(mon->discardOldest)
        queueItem = TAILQ_FIRST(&mon->queue);
    else
        queueItem = TAILQ_LAST(&mon->queue, QueueOfQueueDataValues);
    UA_assert(queueItem); /* When the currentQueueSize > 0, then there is an item */
    TAILQ_REMOVE(&mon->queue, queueItem, listEntry);
    UA_DataValue_deleteMembers(&queueItem->value);
    UA_free(queueItem);
    --mon->currentQueueSize;
}

/* Has this sample changed from the last one? The method may allocate additional
 * space for the encoding buffer. Detect the change in encoding->data. */
static UA_StatusCode
detectValueChange(UA_MonitoredItem *mon, UA_DataValue *value,
                  UA_ByteString *encoding, UA_Boolean *changed) {
    /* Apply Filter */
    UA_Boolean hasValue = value->hasValue;
    if(mon->trigger == UA_DATACHANGETRIGGER_STATUS)
        value->hasValue = false;
    UA_Boolean hasServerTimestamp = value->hasServerTimestamp;
    UA_Boolean hasServerPicoseconds = value->hasServerPicoseconds;
    value->hasServerTimestamp = false;
    value->hasServerPicoseconds = false;
    UA_Boolean hasSourceTimestamp = value->hasSourceTimestamp;
    UA_Boolean hasSourcePicoseconds = value->hasSourcePicoseconds;
    if(mon->trigger < UA_DATACHANGETRIGGER_STATUSVALUETIMESTAMP) {
        value->hasSourceTimestamp = false;
        value->hasSourcePicoseconds = false;
    }

    /* Encode the data for comparison */
    UA_StatusCode retval = UA_STATUSCODE_GOOD;
    size_t binsize = UA_calcSizeBinary(value, &UA_TYPES[UA_TYPES_DATAVALUE]);
    if(binsize == 0) {
        retval = UA_STATUSCODE_BADINTERNALERROR;
        goto cleanup;
    }

    /* Allocate buffer on the heap if necessary */
    if(binsize > UA_VALUENCODING_MAXSTACK &&
       UA_ByteString_allocBuffer(encoding, binsize) != UA_STATUSCODE_GOOD) {
        retval = UA_STATUSCODE_BADOUTOFMEMORY;
        goto cleanup;
    }

    /* Encode the value */
    size_t encodingOffset = 0;
    retval = UA_encodeBinary(value, &UA_TYPES[UA_TYPES_DATAVALUE],
                             NULL, NULL, encoding, &encodingOffset);
    if(retval != UA_STATUSCODE_GOOD)
        goto cleanup;

    /* The value has changed */
    encoding->length = encodingOffset;
    if(!mon->lastSampledValue.data || !UA_String_equal(encoding, &mon->lastSampledValue))
        *changed = true;

 cleanup:
    /* Reset the filter */
    value->hasValue = hasValue;
    value->hasServerTimestamp = hasServerTimestamp;
    value->hasServerPicoseconds = hasServerPicoseconds;
    value->hasSourceTimestamp = hasSourceTimestamp;
    value->hasSourcePicoseconds = hasSourcePicoseconds;
    return retval;
}

void UA_MoniteredItem_SampleCallback(UA_Server *server, UA_MonitoredItem *monitoredItem) {
    UA_Subscription *sub = monitoredItem->subscription;
    if(monitoredItem->monitoredItemType != UA_MONITOREDITEMTYPE_CHANGENOTIFY) {
        UA_LOG_DEBUG_SESSION(server->config.logger, sub->session,
                             "Subscription %u | MonitoredItem %i | "
                             "Not a data change notification",
                             sub->subscriptionID, monitoredItem->itemId);
        return;
    }

    /* Adjust timestampstoreturn to get source timestamp for triggering */
    UA_TimestampsToReturn ts = monitoredItem->timestampsToReturn;
    if(ts == UA_TIMESTAMPSTORETURN_SERVER)
        ts = UA_TIMESTAMPSTORETURN_BOTH;
    else if(ts == UA_TIMESTAMPSTORETURN_NEITHER)
        ts = UA_TIMESTAMPSTORETURN_SOURCE;

    /* Read the value */
    UA_ReadValueId rvid;
    UA_ReadValueId_init(&rvid);
    rvid.nodeId = monitoredItem->monitoredNodeId;
    rvid.attributeId = monitoredItem->attributeID;
    rvid.indexRange = monitoredItem->indexRange;
    UA_DataValue value;
    UA_DataValue_init(&value);
    Service_Read_single(server, sub->session, ts, &rvid, &value);

    /* Stack-allocate some memory for the value encoding */
    UA_Byte *stackValueEncoding = UA_alloca(UA_VALUENCODING_MAXSTACK);
    UA_ByteString valueEncoding;
    valueEncoding.data = stackValueEncoding;
    valueEncoding.length = UA_VALUENCODING_MAXSTACK;

    /* Has the value changed? */
    UA_Boolean changed = false;
    UA_StatusCode retval = detectValueChange(monitoredItem, &value,
                                             &valueEncoding, &changed);
    if(!changed || retval != UA_STATUSCODE_GOOD)
        goto cleanup;

    /* Allocate the entry for the publish queue */
    MonitoredItem_queuedValue *newQueueItem = UA_malloc(sizeof(MonitoredItem_queuedValue));
    if(!newQueueItem) {
        UA_LOG_WARNING_SESSION(server->config.logger, sub->session,
                               "Subscription %u | MonitoredItem %i | "
                               "Item for the publishing queue could not be allocated",
                               sub->subscriptionID, monitoredItem->itemId);
        goto cleanup;
    }

    /* Copy valueEncoding on the heap for the next comparison (if not already done) */
    if(valueEncoding.data == stackValueEncoding) {
        UA_ByteString cbs;
        if(UA_ByteString_copy(&valueEncoding, &cbs) != UA_STATUSCODE_GOOD) {
            UA_LOG_WARNING_SESSION(server->config.logger, sub->session,
                                   "Subscription %u | MonitoredItem %i | "
                                   "ByteString to compare values could not be created",
                                   sub->subscriptionID, monitoredItem->itemId);
            UA_free(newQueueItem);
            goto cleanup;
        }
        valueEncoding = cbs;
    }

    /* Prepare the newQueueItem */
    if(value.hasValue && value.value.storageType == UA_VARIANT_DATA_NODELETE) {
        if(UA_DataValue_copy(&value, &newQueueItem->value) != UA_STATUSCODE_GOOD) {
            UA_LOG_WARNING_SESSION(server->config.logger, sub->session,
                                   "Subscription %u | MonitoredItem %i | "
                                   "Item for the publishing queue could not be prepared",
                                   sub->subscriptionID, monitoredItem->itemId);
            UA_free(newQueueItem);
            goto cleanup;
        }
    } else {
        newQueueItem->value = value;
    }
    newQueueItem->clientHandle = monitoredItem->clientHandle;

    /* <-- Point of no return --> */

    UA_LOG_DEBUG_SESSION(server->config.logger, sub->session,
                         "Subscription %u | MonitoredItem %u | Sampled a new value",
                         sub->subscriptionID, monitoredItem->itemId);

    /* Replace the encoding for comparison */
    UA_ByteString_deleteMembers(&monitoredItem->lastSampledValue);
    monitoredItem->lastSampledValue = valueEncoding;

    /* Add the sample to the queue for publication */
    ensureSpaceInMonitoredItemQueue(monitoredItem);
    TAILQ_INSERT_TAIL(&monitoredItem->queue, newQueueItem, listEntry);
    ++monitoredItem->currentQueueSize;
    return;

 cleanup:
    if(valueEncoding.data != stackValueEncoding)
        UA_ByteString_deleteMembers(&valueEncoding);
    UA_DataValue_deleteMembers(&value);
}

UA_StatusCode
MonitoredItem_registerSampleJob(UA_Server *server, UA_MonitoredItem *mon) {
    UA_Job job;
    job.type = UA_JOBTYPE_METHODCALL;
    job.job.methodCall.method = (UA_ServerCallback)UA_MoniteredItem_SampleCallback;
    job.job.methodCall.data = mon;
    UA_StatusCode retval = UA_Server_addRepeatedJob(server, job,
                                                    (UA_UInt32)mon->samplingInterval,
                                                    &mon->sampleJobGuid);
    if(retval == UA_STATUSCODE_GOOD)
        mon->sampleJobIsRegistered = true;
    return retval;
}

UA_StatusCode MonitoredItem_unregisterSampleJob(UA_Server *server, UA_MonitoredItem *mon) {
    if(!mon->sampleJobIsRegistered)
        return UA_STATUSCODE_GOOD;
    mon->sampleJobIsRegistered = false;
    return UA_Server_removeRepeatedJob(server, mon->sampleJobGuid);
}

/****************/
/* Subscription */
/****************/

UA_Subscription * UA_Subscription_new(UA_Session *session, UA_UInt32 subscriptionID) {
    UA_Subscription *new = UA_malloc(sizeof(UA_Subscription));
    if(!new)
        return NULL;
    new->session = session;
    new->subscriptionID = subscriptionID;
    new->sequenceNumber = 0;
    new->maxKeepAliveCount = 0;
    new->publishingEnabled = false;
    memset(&new->publishJobGuid, 0, sizeof(UA_Guid));
    new->publishJobIsRegistered = false;
    new->currentKeepAliveCount = 0;
    new->currentLifetimeCount = 0;
    new->lastMonitoredItemId = 0;
    new->state = UA_SUBSCRIPTIONSTATE_NORMAL; /* The first publish response is sent immediately */
    LIST_INIT(&new->monitoredItems);
    TAILQ_INIT(&new->retransmissionQueue);
    new->retransmissionQueueSize = 0;
    return new;
}

void UA_Subscription_deleteMembers(UA_Subscription *subscription, UA_Server *server) {
    Subscription_unregisterPublishJob(server, subscription);

    /* Delete monitored Items */
    UA_MonitoredItem *mon, *tmp_mon;
    LIST_FOREACH_SAFE(mon, &subscription->monitoredItems, listEntry, tmp_mon) {
        LIST_REMOVE(mon, listEntry);
        MonitoredItem_delete(server, mon);
    }

    /* Delete Retransmission Queue */
    UA_NotificationMessageEntry *nme, *nme_tmp;
    TAILQ_FOREACH_SAFE(nme, &subscription->retransmissionQueue, listEntry, nme_tmp) {
        TAILQ_REMOVE(&subscription->retransmissionQueue, nme, listEntry);
        UA_NotificationMessage_deleteMembers(&nme->message);
        UA_free(nme);
    }
    subscription->retransmissionQueueSize = 0;
}

UA_MonitoredItem *
UA_Subscription_getMonitoredItem(UA_Subscription *sub, UA_UInt32 monitoredItemID) {
    UA_MonitoredItem *mon;
    LIST_FOREACH(mon, &sub->monitoredItems, listEntry) {
        if(mon->itemId == monitoredItemID)
            break;
    }
    return mon;
}

UA_StatusCode
UA_Subscription_deleteMonitoredItem(UA_Server *server, UA_Subscription *sub,
                                    UA_UInt32 monitoredItemID) {
    UA_MonitoredItem *mon;
    LIST_FOREACH(mon, &sub->monitoredItems, listEntry) {
        if(mon->itemId == monitoredItemID) {
            LIST_REMOVE(mon, listEntry);
            MonitoredItem_delete(server, mon);
            return UA_STATUSCODE_GOOD;
        }
    }
    return UA_STATUSCODE_BADMONITOREDITEMIDINVALID;
}

static size_t
countQueuedNotifications(UA_Subscription *sub, UA_Boolean *moreNotifications) {
    size_t notifications = 0;
    if(sub->publishingEnabled) {
        UA_MonitoredItem *mon;
        LIST_FOREACH(mon, &sub->monitoredItems, listEntry) {
            MonitoredItem_queuedValue *qv;
            TAILQ_FOREACH(qv, &mon->queue, listEntry) {
                if(notifications >= sub->notificationsPerPublish) {
                    *moreNotifications = true;
                    break;
                }
                ++notifications;
            }
        }
    }
    return notifications;
}

static void
UA_Subscription_addRetransmissionMessage(UA_Server *server, UA_Subscription *sub,
                                         UA_NotificationMessageEntry *entry) {
    /* Release the oldest entry if there is not enough space */
    if(server->config.maxRetransmissionQueueSize > 0 &&
       sub->retransmissionQueueSize >= server->config.maxRetransmissionQueueSize) {
        UA_NotificationMessageEntry *lastentry =
            TAILQ_LAST(&sub->retransmissionQueue, UA_ListOfNotificationMessages);
        TAILQ_REMOVE(&sub->retransmissionQueue, lastentry, listEntry);
        --sub->retransmissionQueueSize;
        UA_NotificationMessage_deleteMembers(&lastentry->message);
        UA_free(lastentry);
    }

    /* Add entry */
    TAILQ_INSERT_HEAD(&sub->retransmissionQueue, entry, listEntry);
    ++sub->retransmissionQueueSize;
}

UA_StatusCode
UA_Subscription_removeRetransmissionMessage(UA_Subscription *sub, UA_UInt32 sequenceNumber) {
    UA_NotificationMessageEntry *entry, *entry_tmp;
    TAILQ_FOREACH_SAFE(entry, &sub->retransmissionQueue, listEntry, entry_tmp) {
        if(entry->message.sequenceNumber != sequenceNumber)
            continue;
        TAILQ_REMOVE(&sub->retransmissionQueue, entry, listEntry);
        --sub->retransmissionQueueSize;
        UA_NotificationMessage_deleteMembers(&entry->message);
        UA_free(entry);
        return UA_STATUSCODE_GOOD;
    }
    return UA_STATUSCODE_BADSEQUENCENUMBERUNKNOWN;
}

static UA_StatusCode
prepareNotificationMessage(UA_Subscription *sub, UA_NotificationMessage *message,
                           size_t notifications) {
    /* Array of ExtensionObject to hold different kinds of notifications
       (currently only DataChangeNotifications) */
    message->notificationData = UA_Array_new(1, &UA_TYPES[UA_TYPES_EXTENSIONOBJECT]);
    if(!message->notificationData)
        return UA_STATUSCODE_BADOUTOFMEMORY;
    message->notificationDataSize = 1;

    /* Allocate Notification */
    UA_DataChangeNotification *dcn = UA_DataChangeNotification_new();
    if(!dcn)
        goto cleanup;
    UA_ExtensionObject *data = message->notificationData;
    data->encoding = UA_EXTENSIONOBJECT_DECODED;
    data->content.decoded.data = dcn;
    data->content.decoded.type = &UA_TYPES[UA_TYPES_DATACHANGENOTIFICATION];

    /* Allocate array of notifications */
    dcn->monitoredItems =
        UA_Array_new(notifications, &UA_TYPES[UA_TYPES_MONITOREDITEMNOTIFICATION]);
    if(!dcn->monitoredItems)
        goto cleanup;
    dcn->monitoredItemsSize = notifications;

    /* Move notifications into the response .. the point of no return */
    size_t l = 0;
    UA_MonitoredItem *mon;
    LIST_FOREACH(mon, &sub->monitoredItems, listEntry) {
        MonitoredItem_queuedValue *qv, *qv_tmp;
        TAILQ_FOREACH_SAFE(qv, &mon->queue, listEntry, qv_tmp) {
            if(l >= notifications)
                return UA_STATUSCODE_GOOD;
            UA_MonitoredItemNotification *min = &dcn->monitoredItems[l];
            min->clientHandle = qv->clientHandle;
            min->value = qv->value;
            TAILQ_REMOVE(&mon->queue, qv, listEntry);
            UA_free(qv);
            --mon->currentQueueSize;
            ++l;
        }
    }
    return UA_STATUSCODE_GOOD;
    
 cleanup:
    UA_NotificationMessage_deleteMembers(message);
    return UA_STATUSCODE_BADOUTOFMEMORY;
}

void UA_Subscription_publishCallback(UA_Server *server, UA_Subscription *sub) {
    UA_LOG_DEBUG_SESSION(server->config.logger, sub->session, "Subscription %u | "
                         "Publish Callback", sub->subscriptionID);

    /* Count the available notifications */
    UA_Boolean moreNotifications = false;
    size_t notifications = countQueuedNotifications(sub, &moreNotifications);

    /* Return if nothing to do */
    if(notifications == 0) {
        ++sub->currentKeepAliveCount;
        if(sub->currentKeepAliveCount < sub->maxKeepAliveCount)
            return;
        UA_LOG_DEBUG_SESSION(server->config.logger, sub->session,
                             "Subscription %u | Sending a KeepAlive",
                             sub->subscriptionID)
    }

    /* Check if the securechannel is valid */
    UA_SecureChannel *channel = sub->session->channel;
    if(!channel)
        return;

    /* Dequeue a response */
    UA_PublishResponseEntry *pre = SIMPLEQ_FIRST(&sub->session->responseQueue);

    /* Cannot publish without a response */
    if(!pre) {
        UA_LOG_DEBUG_SESSION(server->config.logger, sub->session,
                             "Subscription %u | Cannot send a publish response "
                             "since the publish queue is empty", sub->subscriptionID)
        if(sub->state != UA_SUBSCRIPTIONSTATE_LATE) {
            sub->state = UA_SUBSCRIPTIONSTATE_LATE;
        } else {
            ++sub->currentLifetimeCount;
            if(sub->currentLifetimeCount > sub->lifeTimeCount) {
                UA_LOG_DEBUG_SESSION(server->config.logger, sub->session, "Subscription %u | "
                                     "End of lifetime for subscription", sub->subscriptionID);
                UA_Session_deleteSubscription(server, sub->session, sub->subscriptionID);
            }
        }
        return;
    }

    UA_PublishResponse *response = &pre->response;
    UA_NotificationMessage *message = &response->notificationMessage;
    UA_NotificationMessageEntry *retransmission = NULL;
    if(notifications > 0) {
        /* Allocate the retransmission entry */
        retransmission = malloc(sizeof(UA_NotificationMessageEntry));
        if(!retransmission) {
            UA_LOG_WARNING_SESSION(server->config.logger, sub->session,
                                   "Subscription %u | Could not allocate memory "
                                   "for retransmission", sub->subscriptionID);
            return;
        }
        /* Prepare the response */
        UA_StatusCode retval =
            prepareNotificationMessage(sub, message, notifications);
        if(retval != UA_STATUSCODE_GOOD) {
            UA_LOG_WARNING_SESSION(server->config.logger, sub->session,
                                   "Subscription %u | Could not prepare the "
                                   "notification message", sub->subscriptionID);
            UA_free(retransmission);
            return;
        }
    }

    /* <-- The point of no return --> */

    /* Remove the response from the response queue */
    SIMPLEQ_REMOVE_HEAD(&sub->session->responseQueue, listEntry);

    /* Set up the response */
    response->responseHeader.timestamp = UA_DateTime_now();
    response->subscriptionId = sub->subscriptionID;
    response->moreNotifications = moreNotifications;
    message->publishTime = response->responseHeader.timestamp;
    if(notifications == 0) {
        /* Send sequence number for the next notification */
        message->sequenceNumber = sub->sequenceNumber + 1;
    } else {
        /* Increase the sequence number */
        message->sequenceNumber = ++sub->sequenceNumber;

        /* Put the notification message into the retransmission queue. This needs to
         * be done here, so that the message itself is included in the available
         * sequence numbers for acknowledgement. */
        retransmission->message = response->notificationMessage;
        UA_Subscription_addRetransmissionMessage(server, sub, retransmission);
    }

    /* Get the available sequence numbers from the retransmission queue */
    size_t available = sub->retransmissionQueueSize;
    if(available > 0) {
        response->availableSequenceNumbers = UA_alloca(available * sizeof(UA_UInt32));
        response->availableSequenceNumbersSize = available;
        size_t i = 0;
        UA_NotificationMessageEntry *nme;
        TAILQ_FOREACH(nme, &sub->retransmissionQueue, listEntry) {
            response->availableSequenceNumbers[i] = nme->message.sequenceNumber;
            ++i;
        }
    }

    /* Send the response */
    UA_LOG_DEBUG_SESSION(server->config.logger, sub->session,
                         "Subscription %u | Sending out a publish response with %u "
                         "notifications", sub->subscriptionID, (UA_UInt32)notifications);
    UA_SecureChannel_sendBinaryMessage(sub->session->channel, pre->requestId, response,
                                       &UA_TYPES[UA_TYPES_PUBLISHRESPONSE]);

    /* Reset subscription state to normal. */
    sub->state = UA_SUBSCRIPTIONSTATE_NORMAL;
    sub->currentKeepAliveCount = 0;
    sub->currentLifetimeCount = 0;
    
    /* Free the response */
    UA_Array_delete(response->results, response->resultsSize,
                    &UA_TYPES[UA_TYPES_UINT32]);
    UA_free(pre); /* no need for UA_PublishResponse_deleteMembers */

    /* Repeat if there are more notifications to send */
    if(moreNotifications)
        UA_Subscription_publishCallback(server, sub);
}

UA_StatusCode
Subscription_registerPublishJob(UA_Server *server, UA_Subscription *sub) {
    if(sub->publishJobIsRegistered)
        return UA_STATUSCODE_GOOD;

    UA_LOG_DEBUG_SESSION(server->config.logger, sub->session,
                         "Subscription %u | Register subscription publishing callback",
                         sub->subscriptionID);
    UA_Job job;
    job.type = UA_JOBTYPE_METHODCALL;
    job.job.methodCall.method = (UA_ServerCallback)UA_Subscription_publishCallback;
    job.job.methodCall.data = sub;
    UA_StatusCode retval =
        UA_Server_addRepeatedJob(server, job, (UA_UInt32)sub->publishingInterval,
                                 &sub->publishJobGuid);
    if(retval == UA_STATUSCODE_GOOD)
        sub->publishJobIsRegistered = true;
    return retval;
}

UA_StatusCode
Subscription_unregisterPublishJob(UA_Server *server, UA_Subscription *sub) {
    if(!sub->publishJobIsRegistered)
        return UA_STATUSCODE_GOOD;
    UA_LOG_DEBUG_SESSION(server->config.logger, sub->session,
                         "Subscription %u | Unregister subscription publishing callback",
                         sub->subscriptionID);
    sub->publishJobIsRegistered = false;
    return UA_Server_removeRepeatedJob(server, sub->publishJobGuid);
}

/* When the session has publish requests stored but the last subscription is
   deleted... Send out empty responses */
void
UA_Subscription_answerPublishRequestsNoSubscription(UA_Server *server, UA_NodeId *sessionToken) {
    /* Get session */
    UA_Session *session = UA_SessionManager_getSession(&server->sessionManager, sessionToken);
    UA_NodeId_delete(sessionToken);

    /* No session or there are remaining subscriptions */
    if(!session || LIST_FIRST(&session->serverSubscriptions))
        return;

    /* Send a response for every queued request */
    UA_PublishResponseEntry *pre;
    while((pre = SIMPLEQ_FIRST(&session->responseQueue))) {
        SIMPLEQ_REMOVE_HEAD(&session->responseQueue, listEntry);
        UA_PublishResponse *response = &pre->response;
        response->responseHeader.serviceResult = UA_STATUSCODE_BADNOSUBSCRIPTION;
        response->responseHeader.timestamp = UA_DateTime_now();
        UA_SecureChannel_sendBinaryMessage(session->channel, pre->requestId, response,
                                           &UA_TYPES[UA_TYPES_PUBLISHRESPONSE]);
        UA_PublishResponse_deleteMembers(response);
        UA_free(pre);
    }
}

#endif /* UA_ENABLE_SUBSCRIPTIONS */