of owls and io objects

Of Owls and IO ObjectsOR network programming with ASIO

Felix MorgnerOct 25, 2017

Institute for SoftwareUniversity of Applied Sciences Rapperswil

Introduction

What is ASIO

• A type of owl• Audio Stream Input/Output• Australian Security Intelligence Organisation• An asynchronous I/O toolkit for C++

1

What is ASIO

• A type of owl

• Audio Stream Input/Output• Australian Security Intelligence Organisation• An asynchronous I/O toolkit for C++

1

What is ASIO

• A type of owl• Audio Stream Input/Output

• Australian Security Intelligence Organisation• An asynchronous I/O toolkit for C++

1

What is ASIO

• A type of owl• Audio Stream Input/Output• Australian Security Intelligence Organisation

• An asynchronous I/O toolkit for C++

1

What is ASIO

• A type of owl• Audio Stream Input/Output• Australian Security Intelligence Organisation• An asynchronous I/O toolkit for C++

1

Why should you care

• Networking TS (N4656)

• Networking is tedious• It’s more than networking

2

Why should you care

• Networking TS (N4656)• Networking is tedious

• It’s more than networking

2

Why should you care

• Networking TS (N4656)• Networking is tedious• It’s more than networking

2

Agenda

Software Design Patterns

ASIO 101

Networking

Beyond Networking

Summary and Q&A

3

Software Design Patterns

Brief History

• Architecture: Christopher Alexander 1977/79• A Place To Wait

• Beck & Cunningham 1987• GoF Patterns (Gamma et al.) 1994• Many more since then

4

Brief History


• Beck & Cunningham 1987

• GoF Patterns (Gamma et al.) 1994• Many more since then

4

Brief History


• Beck & Cunningham 1987• GoF Patterns (Gamma et al.) 1994

• Many more since then

4

Brief History


• Beck & Cunningham 1987• GoF Patterns (Gamma et al.) 1994• Many more since then

4

What Are Patterns

• Solutions to common problems• NOT code

• Descriptions of relevant forces• Language independent

5

What Are Patterns

• Solutions to common problems• NOT code• Descriptions of relevant forces

• Language independent

5

What Are Patterns

• Solutions to common problems• NOT code• Descriptions of relevant forces• Language independent

5

Misconceptions

• Patterns are invented

• GoF patterns are the only patterns• More patterns == Better software• Patterns have no drawbacks• Singleton is a good pattern

6

Misconceptions

• Patterns are invented• GoF patterns are the only patterns

• More patterns == Better software• Patterns have no drawbacks• Singleton is a good pattern

6

Misconceptions

• Patterns are invented• GoF patterns are the only patterns• More patterns == Better software

• Patterns have no drawbacks• Singleton is a good pattern

6

Misconceptions

• Patterns are invented• GoF patterns are the only patterns• More patterns == Better software• Patterns have no drawbacks

• Singleton is a good pattern

6

Misconceptions

• Patterns are invented• GoF patterns are the only patterns• More patterns == Better software• Patterns have no drawbacks• Singleton is a good pattern

6

Pattern Sources

• GoF

• POSA 1, 2, 3, 4• Security Patterns• Patterns for Fault Tolerant Software• Game Programming Patterns• Many, many more

7

Pattern Sources

• GoF• POSA 1, 2, 3, 4

• Security Patterns• Patterns for Fault Tolerant Software• Game Programming Patterns• Many, many more

7

Pattern Sources

• GoF• POSA 1, 2, 3, 4• Security Patterns

• Patterns for Fault Tolerant Software• Game Programming Patterns• Many, many more

7

Pattern Sources

• GoF• POSA 1, 2, 3, 4• Security Patterns• Patterns for Fault Tolerant Software

• Game Programming Patterns• Many, many more

7

Pattern Sources

• GoF• POSA 1, 2, 3, 4• Security Patterns• Patterns for Fault Tolerant Software• Game Programming Patterns

• Many, many more

7

Pattern Sources

• GoF• POSA 1, 2, 3, 4• Security Patterns• Patterns for Fault Tolerant Software• Game Programming Patterns• Many, many more

7

Two Patterns for Asynchronous I/O

• Reactor

• Notify when I/O is ready• “Consumer” must perform I/O

• Proactor• Notify when I/O is done• “Consumer” works with data

8


• Reactor• Notify when I/O is ready• “Consumer” must perform I/O


8



• Proactor

• Notify when I/O is done• “Consumer” works with data

8




8

Proactor Relations

9

ASIO 101

Overview

• Created by Christopher Kohlhoff in 2003

• Part of the Boost libraries since 2008• Available on Linux, BSD, macOS, Windows, …• Based on the Proactor pattern• NOT only for asynchronous I/O

10

Overview

• Created by Christopher Kohlhoff in 2003• Part of the Boost libraries since 2008

• Available on Linux, BSD, macOS, Windows, …• Based on the Proactor pattern• NOT only for asynchronous I/O

10

Overview

• Created by Christopher Kohlhoff in 2003• Part of the Boost libraries since 2008• Available on Linux, BSD, macOS, Windows, …

• Based on the Proactor pattern• NOT only for asynchronous I/O

10

Overview

• Created by Christopher Kohlhoff in 2003• Part of the Boost libraries since 2008• Available on Linux, BSD, macOS, Windows, …• Based on the Proactor pattern

• NOT only for asynchronous I/O

10

Overview

• Created by Christopher Kohlhoff in 2003• Part of the Boost libraries since 2008• Available on Linux, BSD, macOS, Windows, …• Based on the Proactor pattern• NOT only for asynchronous I/O

10

ASIO Hello World

#include <asio.hpp>#include <chrono>#include <iostream>

int main() {auto && service = asio::io_service{};auto && timer = asio::steady_timer{service};

timer.expires_from_now(std::chrono::seconds{1});timer.async_wait([](auto error){std::cout << "timer fired!\n";

});

service.run();}

11

Disecting the Example

• Our Proactor• service = asio::io_service{};

• The I/O object• timer = asio::steady_timer{service};• Our asynchronous operation• timer.async_wait(...)• Our completion handler• [](auto error){ ... }

12


• Our Proactor• service = asio::io_service{};• The I/O object• timer = asio::steady_timer{service};

• Our asynchronous operation• timer.async_wait(...)• Our completion handler• [](auto error){ ... }

12


• Our Proactor• service = asio::io_service{};• The I/O object• timer = asio::steady_timer{service};• Our asynchronous operation• timer.async_wait(...)

• Our completion handler• [](auto error){ ... }

12


• Our Proactor• service = asio::io_service{};• The I/O object• timer = asio::steady_timer{service};• Our asynchronous operation• timer.async_wait(...)• Our completion handler• [](auto error){ ... }

12

This is the basic anatomy of an ASIO program

13

Networking

It’s almost as simple

• OOTB Support for ICMP, TCP, UDP, IPv4/6, Multicast

• Includes support for resolving addresses• Also support TLS through OpenSSL• “Byte-based” and “Condition-based”

14


• OOTB Support for ICMP, TCP, UDP, IPv4/6, Multicast• Includes support for resolving addresses

• Also support TLS through OpenSSL• “Byte-based” and “Condition-based”

14


• OOTB Support for ICMP, TCP, UDP, IPv4/6, Multicast• Includes support for resolving addresses• Also support TLS through OpenSSL

• “Byte-based” and “Condition-based”

14


• OOTB Support for ICMP, TCP, UDP, IPv4/6, Multicast• Includes support for resolving addresses• Also support TLS through OpenSSL• “Byte-based” and “Condition-based”

14

An echo server with:

• N connections

• Output queueing• Automatic connection lifetime

15


• N connections• Output queueing

• Automatic connection lifetime

15


• N connections• Output queueing• Automatic connection lifetime

15

The connection class (head)

struct connection : std::enable_shared_from_this<connection> {// ... members

};

16

The connection class (data members)

struct connection : ... {

private:asio::ip::tcp::socket m_sock;asio::strand m_strand;std::array<char, 1024> m_buff{};std::deque<std::string> m_out{};

};

17

The connection class (ctor)


connection(asio::ip::tcp::socket sock): m_sock{std::move(sock)}, m_strand{m_sock.get_io_service()} {

}

};

18

The connection class (starting communication)


void start() {do_read();

}

};

19

The connection class (reading data)


private:void do_read() {m_sock.async_read_some(asio::buffer(m_buff),

[&, self = shared_from_this()](auto error, auto read) {if(!error) {

auto begin = m_buff.data();auto end = begin + read;m_strand.post([&, data=std::string{begin, end}]{write(data);

});do_read();}

});}

};20

The connection class (writing data part 1)


private:void write(std::string data) {m_out.push_back(data);

if(m_out.size() < 2) {do_write();

}}

};

21

The connection class (writing data part 2)


private:void do_write() {asio::async_write(m_sock, asio::buffer(m_out.front()),

m_strand.wrap([&, self = shared_from_this()](auto error,auto written) {

m_out.pop_front();

if(!error) {if(!m_out.empty()) {do_write();

}}

}));}

};22

Review of the connection class

Connections:

• keep themselves alive• have a single input buffer• have an output queue

23


Connections:

• keep themselves alive

• have a single input buffer• have an output queue

23


Connections:

• keep themselves alive• have a single input buffer

• have an output queue

23


Connections:

• keep themselves alive• have a single input buffer• have an output queue

23

The server class (data members)

struct server {

private:asio::ip::tcp::acceptor m_acceptor;asio::ip::tcp::socket m_sock;

};

24

The server class (creation)

struct server {

server(asio::io_service & service): m_acceptor{service,

asio::ip::tcp::endpoint{asio::ip::tcp::v4(),4321}}

, m_sock{service} {}

};

25

The server class (starting)

struct server {

void start() {do_accept();

}

};

26

The server class (accepting connections)

struct server {

private:void do_accept() {m_acceptor.async_accept(m_sock, [&](auto error){

if(!error) {auto conn = std::make_shared<connection>(std::move(m_sock)

);conn->start();do_accept();

}});

}};

27

Review of the server class

Our server:

• accepts new connections• creates connection objects• does not care about the connections

28


Our server:

• accepts new connections

• creates connection objects• does not care about the connections

28


Our server:

• accepts new connections• creates connection objects

• does not care about the connections

28


Our server:

• accepts new connections• creates connection objects• does not care about the connections

28

Glueing it all together

auto && service = asio::io_service{};auto && server = ::server{service};

server.start();

29

Glueing it all together (contd.)

service.run();

30

Glueing it all together (contd.)

auto const cpus = std::thread::hardware_concurrency();auto pool = std::vector<std::future<void>>{cpus};

for(auto & future : pool) {future = std::async(std::launch::async, [&]{

service.run();});

}

31

Demo Time!

32

There is more

• stream buffers

• conditions• TLS• Name resolution• Synchronous I/O

33

There is more

• stream buffers• conditions

• TLS• Name resolution• Synchronous I/O

33

There is more

• stream buffers• conditions• TLS

• Name resolution• Synchronous I/O

33

There is more

• stream buffers• conditions• TLS• Name resolution

• Synchronous I/O

33

There is more

• stream buffers• conditions• TLS• Name resolution• Synchronous I/O

33

Beyond Networking

It’s More Than Networking

• Signal handling• General worker pool• Stream I/O• Serial ports• Timers• File I/O (Windows)

34


• Signal handling

• General worker pool• Stream I/O• Serial ports• Timers• File I/O (Windows)

34


• Signal handling• General worker pool

• Stream I/O• Serial ports• Timers• File I/O (Windows)

34


• Signal handling• General worker pool• Stream I/O

• Serial ports• Timers• File I/O (Windows)

34


• Signal handling• General worker pool• Stream I/O• Serial ports

• Timers• File I/O (Windows)

34


• Signal handling• General worker pool• Stream I/O• Serial ports• Timers

• File I/O (Windows)

34


• Signal handling• General worker pool• Stream I/O• Serial ports• Timers• File I/O (Windows)

34

Signal handling

auto && signals = asio::signal_set(service, SIGINT);signals.add(SIGINT);signals.async_wait([&](auto error, auto signal){if(!error && !service.stopped()) {std::cout << "Received SIGINT. Terminating. " << '\n';service.stop();

}});

35

Worker Pool (posting the work)

service.post([&]{prove_p_equals_np();

});

36


service.post([&]{factor_large_rsa_key();

});

37


service.post([&]{invent_time_machine();

});

38


service.post([&]{std::do_stuff();

});

39

Worker Pool (running the workers)

auto const cpus = std::thread::hardware_concurrency();auto pool = std::vector<std::future<void>>{cpus};

for(auto & future : pool) {future = std::async(std::launch::async, [&]{

service.run();});

}

40

Summary and Q&A

Conclusion

• ASIO is not a framework!

• It is not that scary• Provides rich I/O and event handling• Parts of it will be standard C++

41

Conclusion

• ASIO is not a framework!• It is not that scary

• Provides rich I/O and event handling• Parts of it will be standard C++

41

Conclusion

• ASIO is not a framework!• It is not that scary• Provides rich I/O and event handling

• Parts of it will be standard C++

41

Conclusion

• ASIO is not a framework!• It is not that scary• Provides rich I/O and event handling• Parts of it will be standard C++

41

Questions?

42

of owls and io objects

Engineering