Making Plans and Changing Your Mind

Usually when you find something, such as a hotel room, you need not only find it, but actually reserve it so you can use it. What good would it be to find that there exists a free room in the Gallery Art Hotel only a hop-step and a jump from the Pointe Vecchio in Florence, when you can't reserve it? The same is true of GAT resources. What if, like above, you found that there were 10 Linux boxes with more than 2 Gigs of memory. Then what? If you couldn't somehow reserve these resources, then by the time you got around to actually trying to use them some other early bird might have gotten your worm. So, you can see that the ability to reserve resources is extremely important, and of course GAT gives you that ability and more.

GAT also allows you to change your mind. Say if you had just finished writing the code for a simulation of two inspiralling black holes so accurate that your reams of code are threaten to collapse into their own event horizon, then you reserve a mare virile enough to ride the burden of your code all the way to coalescence; however, there's many a slip 'twixt the cup and the lip. After making the reservation you realize, to your horror, that an ``off-by-one error'' was introduced in to your most inner of loops. Oops! Now you don't really need this prize mare to be waiting around to dispatch the magic that was your code. You need to cut her loose. GAT allows you to do just this, reserve a resource, then at a later date, cancel this reservation. GAT, manna of the grid application programmer.