This pattern detects a condition and generates alerts based on a condition. (e.g., Alarm on high temperature). These alerts can be based on a simple value or more complex conditions such as rate of increase etc.
In Odysseus generating an altert is simply so create a data pipeline where an element reaches an final operator that sends out the value. E.g. if you use the Select operator to filter out every bid that has a lower price than 400 only bids with a value higher or equals 400 is send to the next operator. An altert can be sending an e-mail (in the following example without authentification at the SMTP server). See Transport handler for further ways to output values.
More complex filter or conditions can be defined using Pattern operator. In each case, the output of an operator would trigger sending an element.