Corona Client Side, I Receive Limitless Messages

Question

I develop a client side on Corona SDK but I have a problem: I can connect to our server and receive the first message from the server. And also I can send back an answer. But afterwards I begin to receive empty strings. I suspect that my client code reads '\0' char every time but I'm not sure. Here is my client code:

( The server sends a message "{ id = 1000 }" in every 5 seconds )

function newConnection( params )
    params = params or {}
    if (not params.server  or not  params.port) then
        print("SERVER OR PORT NOT SPECIFIED");
        return a
    end

    local self = {}
    self.buffer = ""

    self.server =  params.server
    self.port = params.port
    self.isOpen = false

    function self:start( params )
            self.callback = params.callback

            self.sock, err = socket.connect( self.server,  self.port )
            if ( self.sock == nil ) then
                print("COULDN'T CONNECT TO SERVER (self:start): "..err)
                return false;
            else
                print( "Connected." )
            end
            self.isOpen = true
            self.sock:setoption( "tcp-nodelay", true ) -- disable Nagle's algorithm for the connection
            self.sock:settimeout(0)
            self.sock:setoption( "keepalive", true )
            return true
    end

function self:enterFrame()          
    local input,output = socket.select( { self.sock }, nil, 0 ) -- this is a way not to block runtime while reading socket. zero timeout does the trick
    for i,v in ipairs(input) do  -------------

        local got_something_new = false
        while  true  do
            skt, e, p = v:receive()
            if skt      then 
                self.buffer = self.buffer.."__JSON__START__"..skt.."__JSON__END__"; 
                got_something_new = true;  
            end
            if p        then 
                self.buffer = self.buffer.."__JSON__START__"..p.."__JSON__END__";
                got_something_new = true; 
            end
            if not skt  then break; end
            if e        then print( "ERROR: ", e ); break; end
        end

        -- now, checking if a message is present in buffer...
        while got_something_new do  --  this is for a case of several messages stocker in the buffer
            local start = string.find(self.buffer,'__JSON__START__')
            local finish = string.find(self.buffer,'__JSON__END__')
            if (start and finish) then -- found a message!
                local message = string.sub( self.buffer, start+15, finish-1)
                self.buffer = string.sub( self.buffer, 1, start-1 )  ..   string.sub(self.buffer, finish + 13 ) -- cutting our message from buffer
                self.callback(  message  )
            else
                break
            end
        end
    end         
end

Runtime:addEventListener('enterFrame', self)

return self
end

Answer 1

I changed reading routine and it worked fine. Here is the answer :

        for i,v in ipairs(input) do  -------------

            local got_something_new = false
            while  true  do
                skt, e, p = v:receive(1)
                if skt      then
                    if skt ~= '\0' then
                        self.buffer = self.buffer..skt  
                    else
                        got_something_new = true
                        self.buffer = "__JSON__START__"..self.buffer.."__JSON__END__"
                    end
                end
                if p        then 
                    if p ~= '\0' then
                        self.buffer = self.buffer..p;
                    else
                        got_something_new = true
                        self.buffer = "__JSON__START__"..self.buffer.."__JSON__END__"
                    end
                end
                if not skt  then break; end
                if e        then print( "ERROR: ", e ); break; end
            end

            -- now, checking if a message is present in buffer...
            while got_something_new do  --  this is for a case of several messages stocker in the buffer
                local start = string.find(self.buffer,'__JSON__START__')
                local finish = string.find(self.buffer,'__JSON__END__')
                if (start and finish) then -- found a message!
                    local message = string.sub( self.buffer, start+15, finish-1)
                    self.buffer = string.sub( self.buffer, 1, start-1 )  ..   string.sub(self.buffer, finish + 13 ) -- cutting our message from buffer
                    self.callback(  message  )
                else
                    break
                end
            end
        end