How does the Java – airline fare comparison web application get tickets from multiple Airlines?
As mentioned above, only out of morbid curiosity Do airlines' websites have APIs that these engines can use? Or do you write programs to browse various websites and provide input (source, destination, departure date, return) and obtain output (price, time, etc.)?
Editor: OK, I found this after submitting the question Still, I'm interested to see how it's done programmatically In Java, which library is good for this?
Solution
There are several ways to obtain this information
Such APIs can be "modern" soap systems or older things, such as EDI, EJB calls, etc., but the principle still exists: what you ask, their server provides the required information
More morally incorrect, more difficult to implement, and more vulnerable, you can try screen analysis of their booking engine But of course those screen layouts change often:)