checking a swap require a lot of cpu resource, roster normally come out same day of month, every month, at a particular time. Which make very high spike, our flag ship product, iSwap, with the capability looking swap possibility with 10000 other rosters base on user critieria, you need a cloud computing give you this magnitude of computing power. gae did it nicely, user friendly, easy to you, low cost.
I mainly use it to trace how many user using it before my site get monetized, at the age before smartphone and we only have web site, now I look at the profit rather than web page visited. As web page is not the single interface now. Android, iOS, Web. Wasting time to set up one by one. so I just simply look at revenue.
iPhone app, a new born language, it may good but the IDE, xcode is bad compare with Visual Studio. It just like a baby. playground can only use without connect to other library...you can not do a simply refactor of renaming a variable. You can go to definition and find reference, but you can not go to implementation....I should write them on xcode not here basically it is not the fault of swift, but it tightly to it, unless you want to use a notepad to write it.