= Hello World via TCP/IP =

With just seven lines of code you can send and receive the Hello World message in the same session, between workspaces on the same machine, between machines on the same network or any machine connected to the internet. 

These examples are written in APL+WIN to work on the local machine therefore they both refer to the ip address of the local host 127.0.0.1. They can be run as functions or simply typed  in the same order as they appear below and executed sequentially in an active session.

To run between machines on a network or over the internet simply replace the ip address with that of the server machine in both functions and choose any port number outside that used by common services.

These functions are the essential bare bones and require more flesh putting on them to create robust communications systems but they serve to demonstrate the possibilities.

Run as functions in the same session this is what you should see:
{{{
      TcpServer
      TcpClient
Hello World
}}}
{{{
∇  TcpServer;socket;rc                                                                           
                                                                                           
⍝Create a socket                                                                           
socket←¯1↑⎕ni 'Socket'                                                                     
                                                                                           
⍝Bind the socket on port 3000 and the ip address of the server machine                      
rc←socket ⎕ni 'Bind' 3000 '127.0.0.1'                                                     
                                                                                           
⍝Put the socket in listening mode                                                          
rc←socket ⎕ni 'Listen'                                                                    
                                                                                           
⍝Create event handler to accept connection from client and return Hello World              
rc←socket ⎕ni 'onAcceptNotify' 'rc←3⊃⎕ni "Accept" ◊ 0 0⍴rc ⎕ni "Send" "Hello World" "char"'

∇ 
}}}

{{{

∇ TcpClient;socket;hostaddress;service;rc                                   
                                                                       
⍝Create a socket                                                       
socket←¯1↑⎕ni 'Socket'                                                 
                                                                       
⍝Create event handler to read incomming messages                       
rc←socket ⎕ni 'onReadNotify' '3⊃⎕ni "Recv" "char"'                    
                                                                       
⍝Connect the socket on port 3000 to the ip address of the server machine
rc←socket ⎕ni 'Connect' 3000 '127.0.0.1'
                      
∇
}}}
Author: GrahamSteer

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CategoryHelloWorld - CategoryApl2000