Fun With Sockets

7/27/2019 Fun With Sockets

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03/01/13 Mandar Kulkarni 1

BackgroundBasics of Socket ProgrammingZMQ (Zero Message Queues)

Serialization with Google Protocol Buffers

Fun With Sockets


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Background

What is a computer network?

Ref: www.jimdevelopment.com


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Background

A collection of computers interconnected by asingle technology.

Two computers are said to be interconnected

if they are able to exchange information

C1 C2Flow of information


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Background

Ref: Lecture notes of EE 633 by Prof. Bhattacherjee, IIT Guwahati


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Background

Communication as transport of Data bitsFrames Packets

When we transmit a packet into and across the

network, we want to make sure that it istransmitted with no errors so we insert thepacket in a frame.

Ref:http://www.teracomtraining.com/tutorials/teracom-tutorial-packet-frame.htm


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Background

TCP/IP : A family of protocols TCP

Responsible for connection establishment andmanagement and reliable data transport between

software processes on devices IP

Envelopes and addresses the data Enables the network to read the envelope and

forward the data to its destination Defines how much data can fit in a single packet.

Other protocols added to TCP/IP suite UDP, SMTP,FTP, HTTP


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Sockets

A socket is the mechanism that most popular operatingsystems provide to give programs access to the network

Endpoint of a communication system

Maybe inter process or over the Internet

Analogy:

Electrical socket Network socket

Wire Communication channel

Device Network application (say your web browser)


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Sockets

Client Server model


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Sockets

Applications

Web browsers

LAN gaming

Dota, AOE, CS...

Online file transfers

And many more...


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Creating Sockets

In this talk we will have a look at two ways tocreate sockets

Simple socket.h header in C/C++

ZMQ (multiple language support) Another popular implementation is with Boost

asio library in C++


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Creating Sockets With socket.h

Server Routines Telephone Analogy

socket() Installing a telephone line

bind() Assign a phone number to your handset

listen() Continuously monitor if there is anyincoming call

accept() Pick up the phone

read()/write() talk

close() hangup


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Creating Sockets With socket.h

Client Routines Telephony Analogy

socket() Installing a phone line

connect() dial

read()/write() talk

close() hangup


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TCP and UDP Sockets

Ref: learn-networking.com


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TCP sockets at work

Ref: http://www.tenouk.com/Module39a.html


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Intelligent transport layer with zmq socketshaving internal message queuing capability

Supports inter process communication as well

Supports N to N connection via PUB-SUB,REQ-REP, PUSH-PULL

Supported by 30+ languages including C, C+

+, Java, .NET, Python

ZMQ (Zero Message Queues)


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Request-Reply Pattern

Ref: www.zeromq.org


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Publish-Subscribe Pattern

Ref: www.zeromq.org


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Push-Pull Pattern

Ref: www.zeromq.org


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When you send data through sockets it mustbe serialized first

Serialization of objects! (An issue in C++)

Again boost libraries can help Problem: Language dependent for encoding and

decoding

All Google applications use Protocol Buffers

Advantage: No language barrier, supported by largenumber of languages including C++, java, python


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So what's the procedure to serialize

Create a .proto file

Compile using protocol buffer compiler

It will generate .pb.cc and .pb.h files (for C++) foryou where the all functions required for you toserialize/de-serialize the message areautomatically declared and defined

The following example is taken fromhttps://developers.google.com/protocol-buffers/docs/overview


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message Person {required string name = 1;required int32 id = 2;optional string email = 3;enum PhoneType {MOBILE = 0;HOME = 1;WORK = 2;

}message PhoneNumber {

required string number = 1;optional PhoneType type = 2 [default = HOME];}repeated PhoneNumber phone = 4;

}

Example of a simple .proto file


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Example of a serialization

Person person;person.set_name("John Doe");person.set_id(1234);person.set_email("[email protected]");

fstream output("myfile", ios::out | ios::binary);person.SerializeToOstream(&output);

Example of a deserialization

fstream input("myfile", ios::in | ios::binary);

Person person;person.ParseFromIstream(&input);cout


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Simple TCP Socket Demo


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Hope you enjoyed!


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Further Reading

http://www.zeromq.org/

https://developers.google.com/protocol-buffers/

http://www.cs.rutgers.edu/~pxk/rutgers/notes/sockets/index.html

www.stackoverflow.com/questions/5791860/beginners-socket-programming-in-c
http://www.zeromq.org/https://developers.google.com/protocol-buffers/http://www.cs.rutgers.edu/~pxk/rutgers/notes/sockets/index.htmlhttp://www.stackoverflow.com/questions/5791860/beginners-socket-programming-in-chttp://www.stackoverflow.com/questions/5791860/beginners-socket-programming-in-chttp://www.cs.rutgers.edu/~pxk/rutgers/notes/sockets/index.htmlhttps://developers.google.com/protocol-buffers/http://www.zeromq.org/

Documents

Fun With Sockets