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-rw-r--r--libtransport/src/protocols/raaqm.cc714
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diff --git a/libtransport/src/protocols/raaqm.cc b/libtransport/src/protocols/raaqm.cc
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+/*
+ * Copyright (c) 2017-2019 Cisco and/or its affiliates.
+ * 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.
+ */
+
+#include <hicn/transport/interfaces/socket_consumer.h>
+
+#include <implementation/socket_consumer.h>
+#include <protocols/errors.h>
+#include <protocols/indexer.h>
+#include <protocols/raaqm.h>
+
+#include <cstdlib>
+#include <fstream>
+
+namespace transport {
+
+namespace protocol {
+
+using namespace interface;
+
+RaaqmTransportProtocol::RaaqmTransportProtocol(
+ implementation::ConsumerSocket *icn_socket)
+ : TransportProtocol(icn_socket, new ByteStreamReassembly(icn_socket, this)),
+ current_window_size_(1),
+ interests_in_flight_(0),
+ cur_path_(nullptr),
+ t0_(utils::SteadyClock::now()),
+ rate_estimator_(nullptr) {
+ init();
+}
+
+RaaqmTransportProtocol::~RaaqmTransportProtocol() {
+ if (rate_estimator_) {
+ delete rate_estimator_;
+ }
+}
+
+int RaaqmTransportProtocol::start() {
+ if (rate_estimator_) {
+ rate_estimator_->onStart();
+ }
+
+ if (!cur_path_) {
+ // RAAQM
+ double drop_factor;
+ double minimum_drop_probability;
+ uint32_t sample_number;
+ uint32_t interest_lifetime;
+
+ socket_->getSocketOption(RaaqmTransportOptions::DROP_FACTOR, drop_factor);
+ socket_->getSocketOption(RaaqmTransportOptions::MINIMUM_DROP_PROBABILITY,
+ minimum_drop_probability);
+ socket_->getSocketOption(RaaqmTransportOptions::SAMPLE_NUMBER,
+ sample_number);
+ socket_->getSocketOption(GeneralTransportOptions::INTEREST_LIFETIME,
+ interest_lifetime);
+
+ // Rate Estimation
+ double alpha = 0.0;
+ uint32_t batching_param = 0;
+ uint32_t choice_param = 0;
+ socket_->getSocketOption(RateEstimationOptions::RATE_ESTIMATION_ALPHA,
+ alpha);
+ socket_->getSocketOption(
+ RateEstimationOptions::RATE_ESTIMATION_BATCH_PARAMETER, batching_param);
+ socket_->getSocketOption(RateEstimationOptions::RATE_ESTIMATION_CHOICE,
+ choice_param);
+
+ if (choice_param == 1) {
+ rate_estimator_ = new ALaTcpEstimator();
+ } else {
+ rate_estimator_ = new SimpleEstimator(alpha, batching_param);
+ }
+
+ socket_->getSocketOption(RateEstimationOptions::RATE_ESTIMATION_OBSERVER,
+ &rate_estimator_->observer_);
+
+ // Current path
+ auto cur_path = std::make_unique<RaaqmDataPath>(
+ drop_factor, minimum_drop_probability, interest_lifetime * 1000,
+ sample_number);
+ cur_path_ = cur_path.get();
+ path_table_[default_values::path_id] = std::move(cur_path);
+ }
+
+ portal_->setConsumerCallback(this);
+ return TransportProtocol::start();
+}
+
+void RaaqmTransportProtocol::resume() { return TransportProtocol::resume(); }
+
+void RaaqmTransportProtocol::reset() {
+ // Set first segment to retrieve
+ core::Name *name;
+ socket_->getSocketOption(GeneralTransportOptions::NETWORK_NAME, &name);
+ index_manager_->reset();
+ index_manager_->setFirstSuffix(name->getSuffix());
+ std::queue<Interest::Ptr> empty;
+ std::swap(interest_to_retransmit_, empty);
+ stats_->reset();
+
+ // Reset reassembly component
+ reassembly_protocol_->reInitialize();
+
+ // Reset protocol variables
+ interests_in_flight_ = 0;
+ t0_ = utils::SteadyClock::now();
+}
+
+bool RaaqmTransportProtocol::verifyKeyPackets() {
+ return index_manager_->onKeyToVerify();
+}
+
+void RaaqmTransportProtocol::increaseWindow() {
+ // return;
+ double max_window_size = 0.;
+ socket_->getSocketOption(GeneralTransportOptions::MAX_WINDOW_SIZE,
+ max_window_size);
+ if (current_window_size_ < max_window_size) {
+ double gamma = 0.;
+ socket_->getSocketOption(RaaqmTransportOptions::GAMMA_VALUE, gamma);
+
+ current_window_size_ += gamma / current_window_size_;
+ socket_->setSocketOption(GeneralTransportOptions::CURRENT_WINDOW_SIZE,
+ current_window_size_);
+ }
+ rate_estimator_->onWindowIncrease(current_window_size_);
+}
+
+void RaaqmTransportProtocol::decreaseWindow() {
+ // return;
+ double min_window_size = 0.;
+ socket_->getSocketOption(GeneralTransportOptions::MIN_WINDOW_SIZE,
+ min_window_size);
+ if (current_window_size_ > min_window_size) {
+ double beta = 0.;
+ socket_->getSocketOption(RaaqmTransportOptions::BETA_VALUE, beta);
+
+ current_window_size_ = current_window_size_ * beta;
+ if (current_window_size_ < min_window_size) {
+ current_window_size_ = min_window_size;
+ }
+
+ socket_->setSocketOption(GeneralTransportOptions::CURRENT_WINDOW_SIZE,
+ current_window_size_);
+ }
+ rate_estimator_->onWindowDecrease(current_window_size_);
+}
+
+void RaaqmTransportProtocol::afterDataUnsatisfied(uint64_t segment) {
+ // Decrease the window because the timeout happened
+ decreaseWindow();
+}
+
+void RaaqmTransportProtocol::afterContentReception(
+ const Interest &interest, const ContentObject &content_object) {
+ updatePathTable(content_object);
+ increaseWindow();
+ updateRtt(interest.getName().getSuffix());
+ rate_estimator_->onDataReceived((int)content_object.payloadSize() +
+ (int)content_object.headerSize());
+ // Set drop probablility and window size accordingly
+ RAAQM();
+}
+
+void RaaqmTransportProtocol::init() {
+ std::ifstream is(RAAQM_CONFIG_PATH);
+
+ std::string line;
+ raaqm_autotune_ = false;
+ default_beta_ = default_values::beta_value;
+ default_drop_ = default_values::drop_factor;
+ beta_wifi_ = default_values::beta_value;
+ drop_wifi_ = default_values::drop_factor;
+ beta_lte_ = default_values::beta_value;
+ drop_lte_ = default_values::drop_factor;
+ wifi_delay_ = 1000;
+ lte_delay_ = 15000;
+
+ if (!is) {
+ TRANSPORT_LOGW(
+ "WARNING: RAAQM parameters not found at %s, set default values",
+ RAAQM_CONFIG_PATH);
+ return;
+ }
+
+ while (getline(is, line)) {
+ std::string command;
+ std::istringstream line_s(line);
+
+ line_s >> command;
+
+ if (command == ";") {
+ continue;
+ }
+
+ if (command == "autotune") {
+ std::string tmp;
+ std::string val;
+ line_s >> tmp >> val;
+ if (val == "yes") {
+ raaqm_autotune_ = true;
+ } else {
+ raaqm_autotune_ = false;
+ }
+ continue;
+ }
+
+ if (command == "lifetime") {
+ std::string tmp;
+ uint32_t lifetime;
+ line_s >> tmp >> lifetime;
+ socket_->setSocketOption(GeneralTransportOptions::INTEREST_LIFETIME,
+ lifetime);
+ continue;
+ }
+
+ if (command == "retransmissions") {
+ std::string tmp;
+ uint32_t rtx;
+ line_s >> tmp >> rtx;
+ socket_->setSocketOption(GeneralTransportOptions::MAX_INTEREST_RETX, rtx);
+ continue;
+ }
+
+ if (command == "beta") {
+ std::string tmp;
+ line_s >> tmp >> default_beta_;
+ socket_->setSocketOption(RaaqmTransportOptions::BETA_VALUE,
+ default_beta_);
+ continue;
+ }
+
+ if (command == "drop") {
+ std::string tmp;
+ line_s >> tmp >> default_drop_;
+ socket_->setSocketOption(RaaqmTransportOptions::DROP_FACTOR,
+ default_drop_);
+ continue;
+ }
+
+ if (command == "beta_wifi_") {
+ std::string tmp;
+ line_s >> tmp >> beta_wifi_;
+ continue;
+ }
+
+ if (command == "drop_wifi_") {
+ std::string tmp;
+ line_s >> tmp >> drop_wifi_;
+ continue;
+ }
+
+ if (command == "beta_lte_") {
+ std::string tmp;
+ line_s >> tmp >> beta_lte_;
+ continue;
+ }
+
+ if (command == "drop_lte_") {
+ std::string tmp;
+ line_s >> tmp >> drop_lte_;
+ continue;
+ }
+
+ if (command == "wifi_delay_") {
+ std::string tmp;
+ line_s >> tmp >> wifi_delay_;
+ continue;
+ }
+
+ if (command == "lte_delay_") {
+ std::string tmp;
+ line_s >> tmp >> lte_delay_;
+ continue;
+ }
+ if (command == "alpha") {
+ std::string tmp;
+ double rate_alpha = 0.0;
+ line_s >> tmp >> rate_alpha;
+ socket_->setSocketOption(RateEstimationOptions::RATE_ESTIMATION_ALPHA,
+ rate_alpha);
+ continue;
+ }
+
+ if (command == "batching_parameter") {
+ std::string tmp;
+ uint32_t batching_param = 0;
+ line_s >> tmp >> batching_param;
+ socket_->setSocketOption(
+ RateEstimationOptions::RATE_ESTIMATION_BATCH_PARAMETER,
+ batching_param);
+ continue;
+ }
+
+ if (command == "rate_estimator") {
+ std::string tmp;
+ uint32_t choice_param = 0;
+ line_s >> tmp >> choice_param;
+ socket_->setSocketOption(RateEstimationOptions::RATE_ESTIMATION_CHOICE,
+ choice_param);
+ continue;
+ }
+ }
+
+ is.close();
+}
+
+void RaaqmTransportProtocol::onContentObject(
+ Interest::Ptr &&interest, ContentObject::Ptr &&content_object) {
+ // Check whether makes sense to continue
+ if (TRANSPORT_EXPECT_FALSE(!is_running_)) {
+ return;
+ }
+
+ // Call application-defined callbacks
+ ConsumerContentObjectCallback *callback_content_object = VOID_HANDLER;
+ socket_->getSocketOption(ConsumerCallbacksOptions::CONTENT_OBJECT_INPUT,
+ &callback_content_object);
+ if (*callback_content_object) {
+ (*callback_content_object)(*socket_->getInterface(), *content_object);
+ }
+
+ ConsumerInterestCallback *callback_interest = VOID_HANDLER;
+ socket_->getSocketOption(ConsumerCallbacksOptions::INTEREST_SATISFIED,
+ &callback_interest);
+ if (*callback_interest) {
+ (*callback_interest)(*socket_->getInterface(), *interest);
+ }
+
+ if (content_object->getPayloadType() == PayloadType::CONTENT_OBJECT) {
+ stats_->updateBytesRecv(content_object->payloadSize());
+ }
+
+ onContentSegment(std::move(interest), std::move(content_object));
+ scheduleNextInterests();
+}
+
+void RaaqmTransportProtocol::onContentSegment(
+ Interest::Ptr &&interest, ContentObject::Ptr &&content_object) {
+ uint32_t incremental_suffix = content_object->getName().getSuffix();
+
+ // Decrease in-flight interests
+ interests_in_flight_--;
+
+ // Update stats
+ if (!interest_retransmissions_[incremental_suffix & mask]) {
+ afterContentReception(*interest, *content_object);
+ }
+
+ index_manager_->onContentObject(std::move(interest),
+ std::move(content_object));
+}
+
+void RaaqmTransportProtocol::onPacketDropped(
+ Interest::Ptr &&interest, ContentObject::Ptr &&content_object) {
+ uint32_t max_rtx = 0;
+ socket_->getSocketOption(GeneralTransportOptions::MAX_INTEREST_RETX, max_rtx);
+
+ uint64_t segment = interest->getName().getSuffix();
+ ConsumerInterestCallback *callback = VOID_HANDLER;
+ if (TRANSPORT_EXPECT_TRUE(interest_retransmissions_[segment & mask] <
+ max_rtx)) {
+ stats_->updateRetxCount(1);
+
+ callback = VOID_HANDLER;
+ socket_->getSocketOption(ConsumerCallbacksOptions::INTEREST_RETRANSMISSION,
+ &callback);
+ if (*callback) {
+ (*callback)(*socket_->getInterface(), *interest);
+ }
+
+ callback = VOID_HANDLER;
+ socket_->getSocketOption(ConsumerCallbacksOptions::INTEREST_OUTPUT,
+ &callback);
+ if (*callback) {
+ (*callback)(*socket_->getInterface(), *interest);
+ }
+
+ if (!is_running_) {
+ return;
+ }
+
+ interest_retransmissions_[segment & mask]++;
+
+ interest_to_retransmit_.push(std::move(interest));
+ } else {
+ TRANSPORT_LOGE(
+ "Stop: received not trusted packet %llu times",
+ (unsigned long long)interest_retransmissions_[segment & mask]);
+ onContentReassembled(
+ make_error_code(protocol_error::max_retransmissions_error));
+ }
+}
+
+void RaaqmTransportProtocol::onReassemblyFailed(std::uint32_t missing_segment) {
+
+}
+
+void RaaqmTransportProtocol::onTimeout(Interest::Ptr &&interest) {
+ checkForStalePaths();
+
+ const Name &n = interest->getName();
+
+ TRANSPORT_LOGW("Timeout on content %s", n.toString().c_str());
+
+ if (TRANSPORT_EXPECT_FALSE(!is_running_)) {
+ return;
+ }
+
+ interests_in_flight_--;
+
+ uint64_t segment = n.getSuffix();
+
+ // Do not retransmit interests asking contents that do not exist.
+ if (segment > index_manager_->getFinalSuffix()) {
+ return;
+ }
+
+ ConsumerInterestCallback *callback = VOID_HANDLER;
+ socket_->getSocketOption(ConsumerCallbacksOptions::INTEREST_EXPIRED,
+ &callback);
+ if (*callback) {
+ (*callback)(*socket_->getInterface(), *interest);
+ }
+
+ afterDataUnsatisfied(segment);
+
+ uint32_t max_rtx = 0;
+ socket_->getSocketOption(GeneralTransportOptions::MAX_INTEREST_RETX, max_rtx);
+
+ if (TRANSPORT_EXPECT_TRUE(interest_retransmissions_[segment & mask] <
+ max_rtx)) {
+ stats_->updateRetxCount(1);
+
+ callback = VOID_HANDLER;
+ socket_->getSocketOption(ConsumerCallbacksOptions::INTEREST_RETRANSMISSION,
+ &callback);
+ if (*callback) {
+ (*callback)(*socket_->getInterface(), *interest);
+ }
+
+ callback = VOID_HANDLER;
+ socket_->getSocketOption(ConsumerCallbacksOptions::INTEREST_OUTPUT,
+ &callback);
+ if (*callback) {
+ (*callback)(*socket_->getInterface(), *interest);
+ }
+
+ if (!is_running_) {
+ return;
+ }
+
+ interest_retransmissions_[segment & mask]++;
+
+ interest_to_retransmit_.push(std::move(interest));
+
+ scheduleNextInterests();
+ } else {
+ TRANSPORT_LOGE("Stop: reached max retx limit.");
+ onContentReassembled(std::make_error_code(std::errc(std::errc::io_error)));
+ }
+}
+
+void RaaqmTransportProtocol::scheduleNextInterests() {
+ if (TRANSPORT_EXPECT_FALSE(!is_running_ && !is_first_)) {
+ return;
+ }
+
+ if (TRANSPORT_EXPECT_FALSE(interests_in_flight_ >= current_window_size_ &&
+ interest_to_retransmit_.size() > 0)) {
+ // send at least one interest if there are retransmissions to perform and
+ // there is no space left in the window
+ sendInterest(std::move(interest_to_retransmit_.front()));
+ TRANSPORT_LOGD("Window full, retransmit one content interest");
+ interest_to_retransmit_.pop();
+ }
+
+ uint32_t index = IndexManager::invalid_index;
+
+ // Send the interest needed for filling the window
+ while (interests_in_flight_ < current_window_size_) {
+ if (interest_to_retransmit_.size() > 0) {
+ sendInterest(std::move(interest_to_retransmit_.front()));
+ TRANSPORT_LOGD("Retransmit content interest");
+ interest_to_retransmit_.pop();
+ } else {
+ index = index_manager_->getNextSuffix();
+ if (index == IndexManager::invalid_index) {
+ break;
+ }
+
+ sendInterest(index);
+ TRANSPORT_LOGD("Send content interest %u", index);
+ }
+ }
+}
+
+void RaaqmTransportProtocol::sendInterest(std::uint64_t next_suffix) {
+ auto interest = getPacket();
+ core::Name *name;
+ socket_->getSocketOption(GeneralTransportOptions::NETWORK_NAME, &name);
+ name->setSuffix((uint32_t)next_suffix);
+ interest->setName(*name);
+
+ uint32_t interest_lifetime;
+ socket_->getSocketOption(GeneralTransportOptions::INTEREST_LIFETIME,
+ interest_lifetime);
+ interest->setLifetime(interest_lifetime);
+
+ ConsumerInterestCallback *callback = VOID_HANDLER;
+ socket_->getSocketOption(ConsumerCallbacksOptions::INTEREST_OUTPUT,
+ &callback);
+ if (*callback) {
+ callback->operator()(*socket_->getInterface(), *interest);
+ }
+
+ if (TRANSPORT_EXPECT_FALSE(!is_running_ && !is_first_)) {
+ return;
+ }
+
+ // This is set to ~0 so that the next interest_retransmissions_ + 1,
+ // performed by sendInterest, will result in 0
+ interest_retransmissions_[next_suffix & mask] = ~0;
+ interest_timepoints_[next_suffix & mask] = utils::SteadyClock::now();
+ sendInterest(std::move(interest));
+}
+
+void RaaqmTransportProtocol::sendInterest(Interest::Ptr &&interest) {
+ interests_in_flight_++;
+ interest_retransmissions_[interest->getName().getSuffix() & mask]++;
+
+ portal_->sendInterest(std::move(interest));
+}
+
+void RaaqmTransportProtocol::onContentReassembled(std::error_code ec) {
+ rate_estimator_->onDownloadFinished();
+ TransportProtocol::onContentReassembled(ec);
+}
+
+void RaaqmTransportProtocol::updateRtt(uint64_t segment) {
+ if (TRANSPORT_EXPECT_FALSE(!cur_path_)) {
+ throw std::runtime_error("RAAQM ERROR: no current path found, exit");
+ } else {
+ auto now = utils::SteadyClock::now();
+ utils::Microseconds rtt = std::chrono::duration_cast<utils::Microseconds>(
+ now - interest_timepoints_[segment & mask]);
+
+ // Update stats
+ updateStats((uint32_t)segment, rtt.count(), now);
+
+ if (rate_estimator_) {
+ rate_estimator_->onRttUpdate((double)rtt.count());
+ }
+
+ cur_path_->insertNewRtt(rtt.count());
+ cur_path_->smoothTimer();
+
+ if (cur_path_->newPropagationDelayAvailable()) {
+ checkDropProbability();
+ }
+ }
+}
+
+void RaaqmTransportProtocol::RAAQM() {
+ if (!cur_path_) {
+ throw errors::RuntimeException("ERROR: no current path found, exit");
+ exit(EXIT_FAILURE);
+ } else {
+ // Change drop probability according to RTT statistics
+ cur_path_->updateDropProb();
+
+ double coin = ((double)rand() / (RAND_MAX));
+ if (coin <= cur_path_->getDropProb()) {
+ decreaseWindow();
+ }
+ }
+}
+
+void RaaqmTransportProtocol::updateStats(uint32_t suffix, uint64_t rtt,
+ utils::TimePoint &now) {
+ // Update RTT statistics
+ stats_->updateAverageRtt(rtt);
+ stats_->updateAverageWindowSize(current_window_size_);
+
+ // Call statistics callback
+ ConsumerTimerCallback *stats_callback = VOID_HANDLER;
+ socket_->getSocketOption(ConsumerCallbacksOptions::STATS_SUMMARY,
+ &stats_callback);
+ if (*stats_callback) {
+ auto dt = std::chrono::duration_cast<utils::Milliseconds>(now - t0_);
+
+ uint32_t timer_interval_milliseconds = 0;
+ socket_->getSocketOption(GeneralTransportOptions::STATS_INTERVAL,
+ timer_interval_milliseconds);
+ if (dt.count() > timer_interval_milliseconds) {
+ (*stats_callback)(*socket_->getInterface(), *stats_);
+ t0_ = utils::SteadyClock::now();
+ }
+ }
+}
+
+void RaaqmTransportProtocol::updatePathTable(
+ const ContentObject &content_object) {
+ uint32_t path_id = content_object.getPathLabel();
+
+ if (path_table_.find(path_id) == path_table_.end()) {
+ if (TRANSPORT_EXPECT_TRUE(cur_path_ != nullptr)) {
+ // Create a new path with some default param
+
+ if (TRANSPORT_EXPECT_FALSE(path_table_.empty())) {
+ throw errors::RuntimeException(
+ "[RAAQM] No path initialized for path table, error could be in "
+ "default path initialization.");
+ }
+
+ // Initiate the new path default param
+ auto new_path = std::make_unique<RaaqmDataPath>(
+ *(path_table_.at(default_values::path_id)));
+
+ // Insert the new path into hash table
+ path_table_[path_id] = std::move(new_path);
+ } else {
+ throw errors::RuntimeException(
+ "UNEXPECTED ERROR: when running,current path not found.");
+ }
+ }
+
+ cur_path_ = path_table_[path_id].get();
+
+ size_t header_size = content_object.headerSize();
+ size_t data_size = content_object.payloadSize();
+
+ // Update measurements for path
+ cur_path_->updateReceivedStats(header_size + data_size, data_size);
+}
+
+void RaaqmTransportProtocol::checkDropProbability() {
+ if (!raaqm_autotune_) {
+ return;
+ }
+
+ unsigned int max_pd = 0;
+ PathTable::iterator it;
+ for (auto it = path_table_.begin(); it != path_table_.end(); ++it) {
+ if (it->second->getPropagationDelay() > max_pd &&
+ it->second->getPropagationDelay() != UINT_MAX &&
+ !it->second->isStale()) {
+ max_pd = it->second->getPropagationDelay();
+ }
+ }
+
+ double drop_prob = 0;
+ double beta = 0;
+ if (max_pd < wifi_delay_) { // only ethernet paths
+ drop_prob = default_drop_;
+ beta = default_beta_;
+ } else if (max_pd < lte_delay_) { // at least one wifi path
+ drop_prob = drop_wifi_;
+ beta = beta_wifi_;
+ } else { // at least one lte path
+ drop_prob = drop_lte_;
+ beta = beta_lte_;
+ }
+
+ double old_drop_prob = 0;
+ double old_beta = 0;
+ socket_->getSocketOption(RaaqmTransportOptions::BETA_VALUE, old_beta);
+ socket_->getSocketOption(RaaqmTransportOptions::DROP_FACTOR, old_drop_prob);
+
+ if (drop_prob == old_drop_prob && beta == old_beta) {
+ return;
+ }
+
+ socket_->setSocketOption(RaaqmTransportOptions::BETA_VALUE, beta);
+ socket_->setSocketOption(RaaqmTransportOptions::DROP_FACTOR, drop_prob);
+
+ for (it = path_table_.begin(); it != path_table_.end(); it++) {
+ it->second->setDropProb(drop_prob);
+ }
+}
+
+void RaaqmTransportProtocol::checkForStalePaths() {
+ if (!raaqm_autotune_) {
+ return;
+ }
+
+ bool stale = false;
+ PathTable::iterator it;
+ for (it = path_table_.begin(); it != path_table_.end(); ++it) {
+ if (it->second->isStale()) {
+ stale = true;
+ break;
+ }
+ }
+ if (stale) {
+ checkDropProbability();
+ }
+}
+
+} // end namespace protocol
+
+} // namespace transport