Tutorial Addendum on Perl - Allotment B - XML in Applicant and Server Advice

This affiliate describes:

    

    
• Different XML applicant and server advice models.
  
      



    
• XML and Atrium Advice Archetype - GameServer.pl
  
      



    
• XML and Atrium Advice Archetype - GameClient.pl
  
      



    

XML Applicant and Server Advice Model

    

Once we understand how to plan XML strings and hashes, we can now attending at how

    

XML technology can be acclimated in applicant and server communication.

    

The alotof archaic way of using XML technology in applicant and server communication

    

is to address a applicant program and a server program to forward and accept XML messages

    

with TCP atrium advice over Internet. The afterward diagram illustrates how this works:

    

    
Client Arrangement    Server System

    

 

    
   XML  | Internet | XML

    
Client Prog.<--->TCP|<-------------->|TCP<--->Server Prog.

    

To apprentice added about TCP atrium communication, see the "Socket Communication"

    

chapter of this book.

    

XML with Atrium Advice Archetype - GameServer.pl

    

In the afterward example, I wrote a simple applicant and

    

server abject bold application. It s a simple game, in which the server

    

accepts new clients, and holds a amount for the applicant to guess.

    

The advice is exchanged amid the applicant and server in plain

    

XML format, and delivered with apparent TCP advice protocol.

    

Here is the server program, GameServer.pl:

    

 

    
#- GameServer.pl

    
#- Absorb (c) 1999 by Dr. Yang

    
#

    
 use Socket;

    
 use XML::Simple;

    
 $xs = new XML::Simple(keeproot => 1, forcearray => 1);

    
 $gameID = 0;

    
 $number = 0; 

    
 $response = "<s><i>0</i><m>hello</m></s>";

    
 &runServer;

    
 exit;

    
sub runServer {

    
 open(LOG,">> GameServer.log");

    
 select(LOG); $|=1;

    
 open(STDERR, ">&LOG") || die "Die: Ambience STDERR to log file";

    
 open(REC,">> GameServer.rec");

    
 select(REC); $|=1;

    
 socket(SOCK,PF_INET,SOCK_STREAM, tcp );

    
 bind(SOCK, pack_sockaddr_in("8080", INADDR_ANY));

    
 listen(SOCK, 1); # can alone yield one applicant at a time

    
 book LOG localtime().": Alert to anchorage 8080

";

    
 for (;;) {

    
 $cAddress = accept(NEWSOCK,SOCK) || die "Error: Accepting: $!";

    
 ($cPort, $cHost) = unpack_sockaddr_in($cAddress);

    
 $cHostName = inet_ntoa($cHost);

    
 book LOG localtime().": Affiliated with $cHostName at $cPort

";

    
 open(STDIN, "+<&NEWSOCK") || die "Die: Ambience STDIN to socket";

    
 open(STDOUT, "+>&NEWSOCK") || die "Die: Ambience STDOUT to socket";

    
 select(STDOUT); $|=1;

    
 &serve;

    
 close(STDIN);

    
 close(STDOUT);

    
 }

    
}

    
sub serve {

    
 my ($tag,$fin,$msg);

    
 while (<STDIN>) {

    
 /<(w+)>/ && ($tag=$1) unless $tag;

    
 /</$tag>/ && ($fin=$tag) if $tag;

    
 $msg = $msg.$_;

    
 endure if $fin;

    
 }

    
 book REC "$msg

";

    
 my $ref = $xs->XMLin($msg);

    
 if (exists($ref->{c}->->{i})) {

    
 my $gid = $ref->{c}->->{i}->;

    
 my $num = $ref->{c}->->{n}->;

    
 if ($gid == $gameID) {

    
  $msg = &oldGame($gid,$num);

    
 } abroad {

    
  $msg = &invalidGame($gid,$num);

    
 }

    
 } abroad {

    
 $msg = &newGame;

    
 }

    
 book STDOUT $msg;

    
 book REC "$msg

";

    
}

    
sub oldGame {

    
 my ($gid,$num) = @_;

    
 my $ref = $xs->XMLin($response);

    
 my $msg;

    
 if ($num == $number) {

    
 $msg = "Congratulations!

"

    
  ."I accept addition amount amid 0 and 99 for you to guess.";

    
 $gameID++;

    
 $number = rand(100);

    
 } elsif ($num > $number) {

    
 $msg = "Your assumption is too high.

 Amuse create addition quess.";

    
 } abroad {

    
 $msg = "Your assumption is too low.

 Amuse create addition quess.";

    
 }

    
 $ref->{s}->->{i}-> = $gameID;

    
 $ref->{s}->->{m}-> = $msg;

    
 acknowledgment $xs->XMLout($ref); 

    
}

    
sub newGame {

    
 $gameID++;

    
 $number = rand(100);

    
 my $ref = $xs->XMLin($response);

    
 $ref->{s}->->{m}-> = "Welcome to Bold Server!

"

    
 ."I accept a amount amid 0 and 99 for you to guess.";

    
 $ref->{s}->->{i}-> = $gameID;

    
 acknowledgment $xs->XMLout($ref); 

    
}

    
sub invalidGame {

    
 my ($sid,$num) = @_;

    
 my $ref = $xs->XMLin($response);

    
 $ref->{s}->->{m}-> = "Sorry. Your bold ID doesn t exist.";

    
 acknowledgment $xs->XMLout($ref); 

    
}