ApMon Java User Guide

The ApMon archive contains the following files and folders:

There is an additional directory, ApMon_docs, which contains the Doxygen documentation of the source files.

To build ApMon on Linux systems:

To build ApMon on Windows systems:

In this section we show how the ApMon API can be used to write a simple program that sends monitoring datagrams. The source code for this short tutorial (slightly modified) can be found in the Example_2.java file under the examples/ directory. The program generates some double values for a parameter called "my_cpu_load" and sends them to the MonALISA destinations. The number of iterations is given as a command line argument; in each iteration two datagrams are sent, one with timestamp and one without timestamp.

With this example program we'll illustrate the steps that should usually be taken to write a program with ApMon:

1. Import the ApMon package (and possibly other necessary packages):

      import java.util.Vector;
      import java.util.logging.Logger;
      
      import apmon.*;
   

2. Initialize the variables we shall use..

      public class Example_2 {
        private static Logger logger = Logger.getLogger("apmon");
        
        public static void main(String args[]) {
          Vector destList = new Vector(); 
          int nDatagrams = 20;
          ApMon apm = null;
          double val = 0;
          int i, timestamp;
          
          if (args.length == 1)
            nDatagrams = Integer.parseInt(args[0]);
   

3. Construct an ApMon object (in this example we used an intialization list containing the name of a destination host, ui.rogrid.pub.ro, and a webpage where other destination hosts and possibly ApMon options can be specified). The ApMon functions throw exceptions if errors appear, so it is recommended to place them in a try-catch block:

          destList.add(new String("ui.rogrid.pub.ro:8884 password"));
          destList.add(new String("http://lcfg.rogrid.pub.ro/~corina/destinations_2.conf"));
    
          try {
            apm = new ApMon(destList);
          } catch (Exception e) {
            logger.severe("Error initializing ApMon: " + e);
          System.exit(-1);
          }
   

4. Adjust the settings for the ApMon object, if necessary (here we set the time interval for reloading the configuration page to 300 sec, and we change the logging level to DEBUG). This can also be done from the configuration file.

          // set the time interval for periodically checking the 
          // configuration URL
          apm.setRecheckInterval(300);
          // this way we can change the logging level
          apm.setLogLevel("DEBUG");
   

5. Send datagrams; we used here two functions: one that includes a timestamp in the datagram and one that doesn't.

          for (i = 0; i < nDatagrams - 1; i++) {
            val += 0.05;
            if (val > 2)
              val = 0;
      
            logger.info("Sending " + val + " for cpu_load");
          
            try {
              /* use the wrapper function with simplified syntax */
              apm.sendParameter("TestCluster2_java", null, "my_cpu_load", 
              ApMon.XDR_REAL64, new Double(val));
                 
              /* now send a datagram with timestamp (as if this was 5h ago) */
              long crtTime = System.currentTimeMillis();
              timestamp = (int)(crtTime / 1000 - (5 * 3600));
              apm.sendTimedParameter("TestClusterOld2_java", null, "my_cpu_load", 
              ApMon.XDR_REAL64, new Double(val), timestamp);
            } catch(Exception e) {
              logger.warning("Send operation failed: " + e);
            } 
            try {
              Thread.sleep(1000);
            } catch (Exception e) {}
          } // for
   

6. Stop ApMon:

          apm.stopIt();      
        }
      }