Trivial applications¶
Note
To successfully run the following examples, please make sure that NFD is properly configured and running. For more information about NFD, refer to NFD’s official homepage.
Trivial consumer¶
In the following trivial example, a consumer creates a Face with default
transport (UnixTransport) and sends an Interest for
/localhost/testApp/randomData
. While expressing Interest, the app specifies three
callbacks to be called when Data/Nack is retrieved or Interest times out.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 | /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2013-2018 Regents of the University of California.
*
* This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
*
* ndn-cxx library is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later version.
*
* ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
*
* You should have received copies of the GNU General Public License and GNU Lesser
* General Public License along with ndn-cxx, e.g., in COPYING.md file. If not, see
* <http://www.gnu.org/licenses/>.
*
* See AUTHORS.md for complete list of ndn-cxx authors and contributors.
*
* @author Alexander Afanasyev <http://lasr.cs.ucla.edu/afanasyev/index.html>
*/
// correct way to include ndn-cxx headers
// #include <ndn-cxx/face.hpp>
#include "face.hpp"
#include <iostream>
// Enclosing code in ndn simplifies coding (can also use `using namespace ndn`)
namespace ndn {
// Additional nested namespaces can be used to prevent/limit name conflicts
namespace examples {
class Consumer : noncopyable
{
public:
void
run()
{
Interest interest(Name("/example/testApp/randomData"));
interest.setInterestLifetime(2_s); // 2 seconds
interest.setMustBeFresh(true);
m_face.expressInterest(interest,
bind(&Consumer::onData, this, _1, _2),
bind(&Consumer::onNack, this, _1, _2),
bind(&Consumer::onTimeout, this, _1));
std::cout << "Sending " << interest << std::endl;
// processEvents will block until the requested data received or timeout occurs
m_face.processEvents();
}
private:
void
onData(const Interest& interest, const Data& data)
{
std::cout << data << std::endl;
}
void
onNack(const Interest& interest, const lp::Nack& nack)
{
std::cout << "received Nack with reason " << nack.getReason()
<< " for interest " << interest << std::endl;
}
void
onTimeout(const Interest& interest)
{
std::cout << "Timeout " << interest << std::endl;
}
private:
Face m_face;
};
} // namespace examples
} // namespace ndn
int
main(int argc, char** argv)
{
ndn::examples::Consumer consumer;
try {
consumer.run();
}
catch (const std::exception& e) {
std::cerr << "ERROR: " << e.what() << std::endl;
}
return 0;
}
|
Trivial producer¶
The following example demonstrates how to write a simple producer application.
First, the application sets an Interest filter for /localhost/testApp
to receive all
Interests that have this prefix. The Face::setInterestFilter() call accepts two
callbacks; the first will be called when an Interest is received and the second if prefix
registration fails.
After an Interest is received, the producer creates a Data packet with the same name as the received Interest, adds content, and signs it with the system-default identity. It is also possible to specify a particular key to be used during the signing. For more information, refer to KeyChain API documentation.
Finally, after Data packet has been created and signed, it is returned to the requester using Face::put() method.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 | /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2013-2018 Regents of the University of California.
*
* This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
*
* ndn-cxx library is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later version.
*
* ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
*
* You should have received copies of the GNU General Public License and GNU Lesser
* General Public License along with ndn-cxx, e.g., in COPYING.md file. If not, see
* <http://www.gnu.org/licenses/>.
*
* See AUTHORS.md for complete list of ndn-cxx authors and contributors.
*
* @author Alexander Afanasyev <http://lasr.cs.ucla.edu/afanasyev/index.html>
*/
// correct way to include ndn-cxx headers
// #include <ndn-cxx/face.hpp>
// #include <ndn-cxx/security/key-chain.hpp>
#include "face.hpp"
#include "security/key-chain.hpp"
#include <iostream>
// Enclosing code in ndn simplifies coding (can also use `using namespace ndn`)
namespace ndn {
// Additional nested namespaces can be used to prevent/limit name conflicts
namespace examples {
class Producer : noncopyable
{
public:
void
run()
{
m_face.setInterestFilter("/example/testApp",
bind(&Producer::onInterest, this, _1, _2),
RegisterPrefixSuccessCallback(),
bind(&Producer::onRegisterFailed, this, _1, _2));
m_face.processEvents();
}
private:
void
onInterest(const InterestFilter& filter, const Interest& interest)
{
std::cout << "<< I: " << interest << std::endl;
// Create new name, based on Interest's name
Name dataName(interest.getName());
dataName
.append("testApp") // add "testApp" component to Interest name
.appendVersion(); // add "version" component (current UNIX timestamp in milliseconds)
static const std::string content = "HELLO KITTY";
// Create Data packet
shared_ptr<Data> data = make_shared<Data>();
data->setName(dataName);
data->setFreshnessPeriod(10_s); // 10 seconds
data->setContent(reinterpret_cast<const uint8_t*>(content.data()), content.size());
// Sign Data packet with default identity
m_keyChain.sign(*data);
// m_keyChain.sign(data, <identityName>);
// m_keyChain.sign(data, <certificate>);
// Return Data packet to the requester
std::cout << ">> D: " << *data << std::endl;
m_face.put(*data);
}
void
onRegisterFailed(const Name& prefix, const std::string& reason)
{
std::cerr << "ERROR: Failed to register prefix \""
<< prefix << "\" in local hub's daemon (" << reason << ")"
<< std::endl;
m_face.shutdown();
}
private:
Face m_face;
KeyChain m_keyChain;
};
} // namespace examples
} // namespace ndn
int
main(int argc, char** argv)
{
ndn::examples::Producer producer;
try {
producer.run();
}
catch (const std::exception& e) {
std::cerr << "ERROR: " << e.what() << std::endl;
}
return 0;
}
|
Consumer that uses Scheduler¶
The following example demonstrates how to use Scheduler to schedule arbitrary events for execution at specific points of time.
The library internally uses boost::asio::io_service to
implement fully asynchronous NDN operations (i.e., sending and receiving Interests and
Data). In addition to network-related operations, boost::asio::io_service
can be used
to execute any arbitrary callback within the processing thread (run either explicitly via
io.run
or implicitly via Face::processEvents() as in previous examples).
Scheduler is just a wrapper on top of boost::asio::io_service
,
allowing simple interface to schedule tasks at specific times.
The highlighted lines in the example demonstrate all that is needed to express a second Interest approximately 2 seconds after the first one.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 | /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2013-2018 Regents of the University of California.
*
* This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
*
* ndn-cxx library is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later version.
*
* ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
*
* You should have received copies of the GNU General Public License and GNU Lesser
* General Public License along with ndn-cxx, e.g., in COPYING.md file. If not, see
* <http://www.gnu.org/licenses/>.
*
* See AUTHORS.md for complete list of ndn-cxx authors and contributors.
*
* @author Alexander Afanasyev <http://lasr.cs.ucla.edu/afanasyev/index.html>
*/
// correct way to include ndn-cxx headers
// #include <ndn-cxx/face.hpp>
// #include <ndn-cxx/util/scheduler.hpp>
#include "face.hpp"
#include "util/scheduler.hpp"
#include <boost/asio/io_service.hpp>
#include <iostream>
// Enclosing code in ndn simplifies coding (can also use `using namespace ndn`)
namespace ndn {
// Additional nested namespaces can be used to prevent/limit name conflicts
namespace examples {
class ConsumerWithTimer
{
public:
ConsumerWithTimer()
: m_face(m_ioService) // Create face with io_service object
, m_scheduler(m_ioService)
{
}
void
run()
{
Interest interest(Name("/example/testApp/randomData"));
interest.setInterestLifetime(2_s); // 2 seconds
interest.setMustBeFresh(true);
m_face.expressInterest(interest,
bind(&ConsumerWithTimer::onData, this, _1, _2),
bind(&ConsumerWithTimer::onNack, this, _1, _2),
bind(&ConsumerWithTimer::onTimeout, this, _1));
std::cout << "Sending " << interest << std::endl;
// Schedule a new event
m_scheduler.scheduleEvent(3_s, [this] { delayedInterest(); });
// m_ioService.run() will block until all events finished or m_ioService.stop() is called
m_ioService.run();
// Alternatively, m_face.processEvents() can also be called.
// processEvents will block until the requested data received or timeout occurs.
// m_face.processEvents();
}
private:
void
onData(const Interest& interest, const Data& data)
{
std::cout << data << std::endl;
}
void
onNack(const Interest& interest, const lp::Nack& nack)
{
std::cout << "received Nack with reason " << nack.getReason()
<< " for interest " << interest << std::endl;
}
void
onTimeout(const Interest& interest)
{
std::cout << "Timeout " << interest << std::endl;
}
void
delayedInterest()
{
std::cout << "One more Interest, delayed by the scheduler" << std::endl;
Interest interest(Name("/example/testApp/randomData"));
interest.setInterestLifetime(2_s); // 2 seconds
interest.setMustBeFresh(true);
m_face.expressInterest(interest,
bind(&ConsumerWithTimer::onData, this, _1, _2),
bind(&ConsumerWithTimer::onNack, this, _1, _2),
bind(&ConsumerWithTimer::onTimeout, this, _1));
std::cout << "Sending " << interest << std::endl;
}
private:
// Explicitly create io_service object, which can be shared between Face and Scheduler
boost::asio::io_service m_ioService;
Face m_face;
Scheduler m_scheduler;
};
} // namespace examples
} // namespace ndn
int
main(int argc, char** argv)
{
ndn::examples::ConsumerWithTimer consumer;
try {
consumer.run();
}
catch (const std::exception& e) {
std::cerr << "ERROR: " << e.what() << std::endl;
}
return 0;
}
|