ControlPort.java

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package org.nees.daq;

import java.net.*;
import java.io.*;
import java.lang.String.*;
import java.util.StringTokenizer;
import java.util.Vector;

public class ControlPort {
    private BufferedReader    rd;
    private BufferedWriter    wr;
    private boolean connected;

    public ControlPort(Socket socket)
        throws UnknownHostException, IOException 
    {
        rd = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        wr = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
        connected = true;

        System.out.println("Created CP ok");
    }
    
    public String[] getChannels()
        throws IOException
    {
        String      list_command = "list-channels";
        String      delimiter = ",";
        String      raw_list = "";
        String[]    result = new String[0];
        Vector      channels = new Vector();
            
        // No DAQ, no can do
        if(!connected) {
            throw new IOException("DAQ Not connected.");
        }
        
        System.out.println("Requesting DAQ channel list");
        wr.write(list_command + '\n');
        wr.flush();

        raw_list = rd.readLine();

        System.out.println("Got: " + raw_list);

        // Have the comma-delimted list, now need to parse same
        StringTokenizer tokens = new StringTokenizer(raw_list, delimiter);
        
        String tok;
        while(tokens.hasMoreTokens()) {
            tok = tokens.nextToken();
            // Add channel to list
            channels.addElement(tok);
        }
        // convert channel list to array
        result = new String[channels.size()];
        
        for (int i = 0; i < channels.size(); i++)
            result[i] = (String) channels.elementAt(i);
            
        return(result);
    }
        
    private void subUnsub(String channel, boolean subscribe)
        throws IOException
    {
        String[]    commands = {"open-port", "close-port"};
        String[]    responses = {"Streaming", "Stopping"};
        String[]    stdout = {"Subscribing to", "Unsubscribing from"};
        int         cmd_idx;
        
        if(subscribe)
            cmd_idx = 0;
        else
            cmd_idx = 1;
        
        if(!connected) {
            throw new IOException("DAQ not connected");
        }

        System.out.println(stdout[cmd_idx] + " channel " + channel);
        
        wr.write(commands[cmd_idx] + " " + channel + '\n');
        wr.flush();
        
        String response = rd.readLine();
        
        // check for correct response
        if(response.startsWith(responses[cmd_idx])) {
            return;
        }else {
            throw new IOException("Response Error on channel " + channel +
                               " :" + response);
        }
    }

    public void subscribe(String channel)
        throws IOException
    {
        subUnsub(channel, true);
    }

    public void unsubscribe(String channel)
        throws IOException
    {
        subUnsub(channel, false);
    }
}

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