Limit(userID, stockName, percentageChange)

Limit(1, "ACME", 5.0)

event StockTick {
   string name;
   float price;
}
 
event Limit {
   integer userID;
   string name;
   float limit;
}
 
monitor SharePriceTracking {
 
   // store the user's specified attributes
   Limit limit;
 
   // store the initial price (this may be the opening price)
   StockTick initialPrice;
 
   // store the latest price – to give to the user
   StockTick latestPrice;
 
   // when a limit event is received spawn; creating a new
   // monitor instance for each user's request
   action onload() {
      on all Limit(*,*,>0.0):limit spawn setupNewLimitMonitor();
   }
 
   // If an identical request from a user is discovered
   // stop this monitor and die
   // If a StockTick event is received for the stock the
   // user specified, store the price and call setPrice
   action setupNewLimitMonitor() {
      on Limit(limit.userID, limit.name, *) die;
      on StockTick(limit.name, *):initialPrice setPrice();
   }
 
   // Search for StockTick events of the specified stock name
   // whose price is both greater and less than the value
   // specified – also converting the value to percentile format
   action setPrice() {
      on StockTick(limit.name, > initialPrice.price * (1.0 +
         (limit.limit/100.0))):latestPrice notifyUser();
     
      on StockTick(limit.name, < initialPrice.price * (1.0 -
        (limit.limit/100.0))):latestPrice notifyUser();
   }
 
   // display results to user
   action notifyUser() {
      log  "Limit alert. User=" +
        limit.userID.toString() +
        " Stock=" + limit.name +
        " Last Price=" + latestPrice.price.toString() +
        " Limit=" + limit.limit.toString();
      die;
   }
}