22.1.4 Board

The board can be realized as an instance of the mail box model where all agents connected to the board read all mails send. The variable Board is bound to a record with three features items, post, startAgent. The feature items gives access to the stream of all items on the board. The features post and code proglang=oz/startAgent/ provide the expected facilities.

<Board>=

local 
   Items  
   local 
      MailBox={Port.new Items}
   in 
      proc {Post Item}
         {Port.send MailBox Item}
      end 
   end 
   <StartAgent>  
in 
   Board = board(items:Items  
                 post:Post  
                 startAgent:StartAgent)
end