I would have nothing against a site that sends me source code to be compiled within my computer so it could run inside a sandbox, but I won't like when Facebook starts pushing binaries I should trust won't break out of the sandbox they should respect. You can't easily do static analysis on binaries.
And I would love to be able to browse the web on my SPARC, POWER and MIPS boxes.
The binary format in question here is LLVM-BC, which is just a compact representation of LLVM-IR, which is a single-static-assignment representation specifically designed for static analysis. SPARC, POWER and MIPS backends already exist, FWIW.
So, you would be happy if a banner served through Facebook could push a obfuscated (good guys may well play by the rules, but bad guys will figure out in no time how to circumvent anything LLVM-BC brings to the table) binary blob to be executed in your browser? How much would you trust the LLVM-based sandbox?
Well... I wouldn't.
In fact, I can't understand why taking more or less the same shortcut to a dead-end Java took a decade-and-half ago is suddenly a good idea and why disagreeing with it means dooming the web to failure.
That's what I'm getting at here. Executing remotely downloaded code is scary, but we already do that.
And the problem with Java was that it had terrible performance. The idea of NaCL is that it will actually perform better than what we have now.
> And the problem with Java was that it had terrible performance.
It had, indeed, terrible performance in 1996.
> The idea of NaCL is that it will actually perform better than what we have now.
The original article here does an excellent job of explaining why. Did you read it? In particular, his reference to Tom Forsyth's article on Moore's Law versus Duck Typing is very informative. And his reference to the game Supreme Commander makes it pretty clear what level of performance he would like to see web-deployable pieces of code achieve.
Those years of experience can be brought to either solution, can't they?
I watched the video that junkbit posted a link to here, and they appear to not trust the llvm-bc. Once the bitcode is translated to a native executable, they run a verifier on the resulting binary, and if the verifier is unable to prove that the only instructions that can execute are those in thi binary, then they have a strict policy of not letting it run. In addition to that, the translator itself runs as a NaCl module so that if a bug is found, it cannot be maliciously used to escalate privileges.