Identifying and Eliminating Web Services Transaction, by Helen Thomas
WSJ Vol 02 Issue 09 - pg.14

	


Listing 1

public class getQuote {
  public static void main (String[] args) throws Exception {

    // Process the arguments.
    int offset = 3 - args.length;
    String encodingStyleURI = args.length == 3
                              ? args[0].substring(1)
                              : Constants.NS_URI_SOAP_ENC;
    URL url = new URL (args[1 - offset]);
    String symbol = args[2 - offset];

    // Build the call.
    Call call = new Call ();
    call.setTargetObjectURI ("urn:xmltoday-delayed-quotes");
    call.setMethodName ("getQuote");
    call.setEncodingStyleURI(encodingStyleURI);
    Vector params = new Vector ();
    params.addElement (new Parameter("symbol", 
      String.class, symbol, null));
    call.setParams (params);

    // Make the call. 
    Response resp = call.invoke (/* router URL */ url, /* 
        actionURI */ "" );

    // Check the response.
    if (resp.generatedFault ()) {
      Fault fault = resp.getFault ();
      System.out.println ("Ouch, the call failed: ");
    } else {
      Parameter result = resp.getReturnValue ();
      System.out.println (result.getValue ());
    }
  }
}

Listing 2

public synchronized void addObject(Object key, Object value) 
{
if (key != null && value != null) 
{
cache.put(key, value);		
}
}

public Object fetchObject(Object key) 
{
if (key == null)
{
return null;
}
return cache.get(key);
}

Listing 3

public StockQuote getQuote(String symbol) 
{
StockQuote stockQuote = null;
if(symbol != null) 
{
stockQuote = (StockQuote) cache.fetchObject(symbol);
if(stockQuote == null) 
{
synchronized(cache)
{
   stockQuote = (StockQuote) cache.fetchObject(symbol);
   if(stockQuote != null) 
   {
      return(stockQuote);
   }
      Vector params = new Vector();
      params.addElement(new Parameter("symbol", 
        String.class,     symbol, null));
      stockQuote = (StockQuote) soap.invoke("getQuote", 
         params);
      if(stockQuote != null) 
      {
         cache.addObject(stockQuote.getSymbol(), stockQuote);
      }
}
}
}
return stockQuote;
}