Java and Flash failed to deliver its promise of unbreakable sandbox where one could run anything without risking compromising host. They tried, but their implementations were ridden with vulnerabilities and eventually browsers made them unusable. Other mentioned technologies didn't even promise that, I think.
JavaScript did deliver its promise of unbreakable sandbox and nowadays browser runs JavaScript, downloaded from any domain without asking user whether he trusts it or not.
WASM builds on JavaScript engine, delivering similar security guarantees.
So there's no fundamental difference between WASM and JVM bytecode. There's only practical difference: WASM proved to be secure and JVM did not.
So now Google Chrome is secure enough for billions of people to safely run evil WASM without compromising their phones, and you can copy this engine from Google Chrome to server and use this strong sandbox to run scripts from various users, which could share resources.
An alternative is to use virtualization. So you can either compile your code to WASM blob and run it in the big WASM server, or you can compile your code to amd64 binary, put it along stripped Linux kernel and run this thing in the VM. There's no clear winner here, I think, for now, there are pros and cons for every approach.
JavaScript did deliver its promise of unbreakable sandbox and nowadays browser runs JavaScript, downloaded from any domain without asking user whether he trusts it or not.
WASM builds on JavaScript engine, delivering similar security guarantees.
So there's no fundamental difference between WASM and JVM bytecode. There's only practical difference: WASM proved to be secure and JVM did not.
So now Google Chrome is secure enough for billions of people to safely run evil WASM without compromising their phones, and you can copy this engine from Google Chrome to server and use this strong sandbox to run scripts from various users, which could share resources.
An alternative is to use virtualization. So you can either compile your code to WASM blob and run it in the big WASM server, or you can compile your code to amd64 binary, put it along stripped Linux kernel and run this thing in the VM. There's no clear winner here, I think, for now, there are pros and cons for every approach.