This affiliate explains:
- What is a socket.
- How to authorize a atrium communication.
- A simple archetype of atrium server application.
- A simple archetype of atrium applicant application.
- Built-in arrangement account functions.
- Socket module.
What Is a Socket
Socket: An abstraction represents one end-point of a two-way communication
link amid two programs active on the Internet network.
Internet Address: A different amount to analyze anniversary computer arrangement on
Port: A amount apery an access point of on a computer arrangement on
the Internet, area a two-way advice hotlink can be established.
Local System: The computer arrangement at this end of a two-way communication
Remote System: The computer arrangement at the additional end of a two-way
A two-way advice hotlink on the Internet involves:
- Two computer systems, anniversary has its own Internet address.
- A anchorage amount on anniversary computer arrangement that is acclimated alone by this
- An appliance program on anniversary computer arrangement that uses this
- A atrium handle created in the appliance program that represents
this advice link.
- The appliance program can use the atrium as a analytic ascribe or
output accessory to accept or forward data from or to the appliance program
running at the additional end of the advice link.
- The appliance program can aswell concern the atrium for advice
about the advice link, like: The Internet abode and anchorage amount
at this end of the advice link; The Internet abode and anchorage amount
at the additional end of the advice link.
The afterward diagram illustrates how an appliance program can use a atrium
to allocution with additional appliance program active on addition computer system
through a two-way advice hotlink on the Internet:
Computer Arrangement I Computer Arrangement II
i/o |Address a| Internet |Address b| i/o
App. A<--->Socket|Port 1 |<-------------->| Anchorage 2|Socket<--->App. B
Establishing a Atrium Communication
In the antecedent section, we alone discussed about how atrium works with
a advice hotlink that has been accustomed already. Now, let s see
how two appliance programs can authorize a advice hotlink between
To authorize a advice link, one appliance program haveto act
as a server , make a server atrium with a accustomed anchorage number, and
set the server atrium in the accept approach cat-and-mouse for a affiliation request
from additional program.
With one program active as a server alert for a affiliation request
at a specific anchorage number, the additional program can now make atrium with
a accustomed bounded anchorage number, the Internet abode of the computer arrangement
where the first program is running, and the anchorage amount area the server
socket is listening. At this time, a affix appeal will be forward over
to the server socket. The server atrium should then acquire the affix
request and instantiate a atrium item to complete advice link.
Perl offers several congenital functions to abutment atrium communication:
socket() - Creates a atrium handle for the defined advice domain, blazon and protocol.
$domain = 2; # Internet domain
$type = 1; # Sequenced, reliable, two-way connection, byte streams
$proto = 6; # Manual Ascendancy Agreement (TCP)
bind() - Binds a atrium handle to a bounded abode that represents a anchorage on the bounded system.
$domain = 2; # Internet domain
$host = pack( C4 , 127,0,0,1); # localhost = 127.0.0.1
$port = 8888;
$address = pack( S n a4 x8 , $domain, $port, $host);
Note that host IP abode haveto be arranged into a 4-byte number, then put it into
the abode anatomy with the anchorage amount using the afterward architecture codes:
S An bearding abbreviate value. 16 bits
n An bearding abbreviate in "network" (big-endian) order. 16 bits
a A cord with approximate bifold data, will be absent padded.
x A absent byte.
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