This has nothing to do with tools running on a server. The "compiler as a service" phrase they were using apparently misled people into thinking it had something to do with "software as a service", which is why they aren't using it anymore. It's about allowing external programs to plug into the compiler pipeline and reuse its syntactic and semantic analysis capabilities.

As mentioned in the link, there are two presentations you can view.

Interesting demo during BUILD: http://channel9.msdn.com/Events/BUILD/BUILD2011/TOOL-816T

You can skip to 35:40ish

Cool presentation from MSR: http://research.microsoft.com/apps/video/?id=152281

You can skip to around 5:00

The build video is somewhat amusing to me. The crowd was WAY into the REPL demo, wherein they showed things that any dynamic language has been doing for decades, all the while trumpeting the "power of static typing". There IS power in static typing, but by the time you're in the REPL you don't need much of it.

Intellisense in a REPL based on static type information is novel, as far as I know. Some dynamic languages do this based on dynamic type information, but that is limited to expressions whose value is known. For example you have a variable A in scope at the REPL, and it has a method A.foo(), then you'll get completion on .foo. But you'll not get completion on A.foo().bar(), because the value of A.foo() is not known at the time of typing that expression.

I dunno, the reliability of Intellisense static typing gives combined with a REPL would be even more useful for exploration.

That aside, it's exciting to have the ability to have both.

I was equally confused about this for a while. With SaaS in practice being "runs on the vendor's servers", I think "CaaS" is a badly chosen name.

I think it's ridiculous to thumb down the parent just because he misunderstood this.