The Knock Knock Protocol

Introduction The Client The Server The Knock Knock Protocol References

THE KNOCK KNOCK PROTOCOL

Muhammad Adil Raja

Roaming Researchers, R©.

cbna

December 2, 2015

Muhammad Adil Raja Roaming Researchers, R©.cbnaThe Knock Knock Protocol


OUTLINE

1 INTRODUCTION

2 THE CLIENT

3 THE SERVER

4 THE KNOCK KNOCK PROTOCOL

5 REFERENCES



OUTLINE

1 INTRODUCTION

2 THE CLIENT

3 THE SERVER


5 REFERENCES



OUTLINE

1 INTRODUCTION

2 THE CLIENT

3 THE SERVER


5 REFERENCES



OUTLINE

1 INTRODUCTION

2 THE CLIENT

3 THE SERVER


5 REFERENCES



OUTLINE

1 INTRODUCTION

2 THE CLIENT

3 THE SERVER


5 REFERENCES



INTRODUCTION



THE CLIENT I

/∗∗ Copyr ight ( c ) 1995 , 2013 , Oracle and / or i t s a f f i l i a t e s . A l l r i g h t s reserved .∗∗ R e d i s t r i b u t i o n and use i n source and b inary forms , w i th or w i thou t∗ mod i f i ca t i on , are permi t ted provided t h a t the f o l l o w i n g cond i t i ons∗ are met :∗∗ − R e d i s t r i b u t i o n s o f source code must r e t a i n the above copy r i gh t∗ not ice , t h i s l i s t o f cond i t i ons and the f o l l o w i n g d i sc l a ime r .∗∗ − R e d i s t r i b u t i o n s i n b inary form must reproduce the above copy r i gh t∗ not ice , t h i s l i s t o f cond i t i ons and the f o l l o w i n g d i sc l a ime r i n the∗ documentation and / or o ther ma te r i a l s prov ided wi th the d i s t r i b u t i o n .∗∗ − Nei ther the name of Oracle or the names of i t s∗ c o n t r i b u t o r s may be used to endorse or promote products der ived∗ from t h i s sof tware w i thou t s p e c i f i c p r i o r w r i t t e n permiss ion .∗∗ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS∗ IS " AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING , BUT NOT LIMITED TO,∗ THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR∗ PURPOSE ARE DISCLAIMED . IN NO EVENT SHALL THE COPYRIGHT OWNER OR∗ CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT , INCIDENTAL , SPECIAL ,∗ EXEMPLARY, OR CONSEQUENTIAL DAMAGES ( INCLUDING , BUT NOT LIMITED TO,∗ PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR



THE CLIENT II∗ PROFITS ; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF∗ LIABILITY , WHETHER IN CONTRACT, STRICT LIABILITY , OR TORT ( INCLUDING∗ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS∗ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.∗ /

import java . i o .∗ ;import java . net .∗ ;

public class KnockKnockClient {public s t a t i c void main ( S t r i n g [ ] args ) throws IOExcept ion {

i f ( args . leng th != 2) {System . e r r . p r i n t l n (

" Usage : java EchoCl ient <host name> < po r t number>" ) ;System . e x i t ( 1 ) ;

}

S t r i n g hostName = args [ 0 ] ;i n t portNumber = In tege r . pa rse In t ( args [ 1 ] ) ;

t ry (Socket kkSocket = new Socket ( hostName , portNumber ) ;P r i n t W r i t e r out = new P r i n t W r i t e r ( kkSocket . getOutputStream ( ) , true ) ;BufferedReader i n = new BufferedReader (

new InputStreamReader ( kkSocket . get InputStream ( ) ) ) ;



THE CLIENT III) {

BufferedReader s td In =new BufferedReader (new InputStreamReader ( System . i n ) ) ;

S t r i n g fromServer ;S t r i n g fromUser ;

while ( ( f romServer = i n . readLine ( ) ) != nul l ) {System . out . p r i n t l n ( " Server : " + fromServer ) ;i f ( f romServer . equals ( " Bye . " ) )

break ;

fromUser = s td In . readLine ( ) ;i f ( fromUser != nul l ) {

System . out . p r i n t l n ( " C l i e n t : " + fromUser ) ;out . p r i n t l n ( fromUser ) ;

}}

} catch ( UnknownHostException e ) {System . e r r . p r i n t l n ( "Don ’ t know about host " + hostName ) ;System . e x i t ( 1 ) ;

} catch ( IOExcept ion e ) {System . e r r . p r i n t l n ( " Couldn ’ t get I /O f o r the connect ion to " +

hostName ) ;System . e x i t ( 1 ) ;

}}



THE CLIENT IV

}



THE SERVER I




THE SERVER II∗ PROFITS ; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF∗ LIABILITY , WHETHER IN CONTRACT, STRICT LIABILITY , OR TORT ( INCLUDING∗ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS∗ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.∗ /

import java . net .∗ ;import java . i o .∗ ;

public class KnockKnockServer {public s t a t i c void main ( S t r i n g [ ] args ) throws IOExcept ion {

i f ( args . leng th != 1) {System . e r r . p r i n t l n ( " Usage : java KnockKnockServer < po r t number>" ) ;System . e x i t ( 1 ) ;

}

i n t portNumber = In tege r . pa rse In t ( args [ 0 ] ) ;

t ry (ServerSocket serverSocket = new ServerSocket ( portNumber ) ;Socket c l i en t Socke t = serverSocket . accept ( ) ;P r i n t W r i t e r out =

new P r i n t W r i t e r ( c l i en t Socke t . getOutputStream ( ) , true ) ;BufferedReader i n = new BufferedReader (

new InputStreamReader ( c l i en tSo cke t . get InputStream ( ) ) ) ;



THE SERVER III

) {

S t r i n g inpu tL ine , ou tpu tL ine ;

/ / I n i t i a t e conversat ion wi th c l i e n tKnockKnockProtocol kkp = new KnockKnockProtocol ( ) ;ou tpu tL ine = kkp . processInput ( nul l ) ;out . p r i n t l n ( ou tpu tL ine ) ;

while ( ( i npu tL ine = i n . readLine ( ) ) != nul l ) {ou tpu tL ine = kkp . processInput ( i npu tL ine ) ;out . p r i n t l n ( ou tpu tL ine ) ;i f ( ou tpu tL ine . equals ( " Bye . " ) )

break ;}

} catch ( IOExcept ion e ) {System . out . p r i n t l n ( " Except ion caught when t r y i n g to l i s t e n on po r t "

+ portNumber + " or l i s t e n i n g f o r a connect ion " ) ;System . out . p r i n t l n ( e . getMessage ( ) ) ;

}}

}



THE KNOCK KNOCK PROTOCOL I




THE KNOCK KNOCK PROTOCOL II∗ PROFITS ; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF∗ LIABILITY , WHETHER IN CONTRACT, STRICT LIABILITY , OR TORT ( INCLUDING∗ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS∗ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.∗ /

import java . net .∗ ;import java . i o .∗ ;

public class KnockKnockProtocol {private s t a t i c f i n a l i n t WAITING = 0;private s t a t i c f i n a l i n t SENTKNOCKKNOCK = 1;private s t a t i c f i n a l i n t SENTCLUE = 2;private s t a t i c f i n a l i n t ANOTHER = 3;

private s t a t i c f i n a l i n t NUMJOKES = 5;

private i n t s ta te = WAITING ;private i n t cur rentJoke = 0;

private S t r i n g [ ] c lues = { " Turn ip " , " L i t t l e Old Lady " , " Atch " , "Who" , "Who" } ;private S t r i n g [ ] answers = { " Turn ip the heat , i t ’ s co ld i n here ! " ,

" I d idn ’ t know you could yodel ! " ," Bless you ! " ," I s there an owl i n here? " ," I s there an echo i n here? " } ;



THE KNOCK KNOCK PROTOCOL III

public S t r i n g processInput ( S t r i n g the Inpu t ) {S t r i n g theOutput = nul l ;

i f ( s t a t e == WAITING) {theOutput = " Knock ! Knock ! " ;s t a t e = SENTKNOCKKNOCK;

} else i f ( s t a t e == SENTKNOCKKNOCK) {i f ( t he Inpu t . equalsIgnoreCase ( "Who ’ s there ? " ) ) {

theOutput = c lues [ cur rentJoke ] ;s t a t e = SENTCLUE;

} else {theOutput = "You ’ re supposed to say \ "Who ’ s there ? \ " ! " +

" Try again . Knock ! Knock ! " ;}

} else i f ( s t a t e == SENTCLUE) {i f ( t he Inpu t . equalsIgnoreCase ( c lues [ cur rentJoke ] + " who? " ) ) {

theOutput = answers [ cur rentJoke ] + " Want another? ( y / n ) " ;s t a t e = ANOTHER;

} else {theOutput = "You ’ re supposed to say \ " " +

c lues [ cur rentJoke ] +" who ? \ " " +" ! Try again . Knock ! Knock ! " ;

s t a t e = SENTKNOCKKNOCK;}



THE KNOCK KNOCK PROTOCOL IV

} else i f ( s t a t e == ANOTHER) {i f ( t he Inpu t . equalsIgnoreCase ( " y " ) ) {

theOutput = " Knock ! Knock ! " ;i f ( cur rentJoke == (NUMJOKES − 1 ) )

cur rentJoke = 0;else

cur rentJoke ++;s ta t e = SENTKNOCKKNOCK;

} else {theOutput = " Bye . " ;s t a t e = WAITING ;

}}return theOutput ;

}}



REFERENCES

The source code has been taken fromhere.This presentation has been produced with LATEX.Berlin, beetle.


https://docs.oracle.com/javase/tutorial/networking/sockets/clientServer.html

Engineering

The Knock Knock Protocol