WebSocket Flash Fallback Fails

[jvilk]

In older browsers without WebSockets, WebSockify attempts to load a Flash file as a polyfill.

But it doesn't load properly.

WebSockify uses its own load_scripts function to dynamically pull in polyfills at runtime, which clashes with RequireJS. In addition, it requires access to the SWF file in the build directory at a particular location relative to the WebSockify JavaScript file.

Proposed solution:

• Do not bundle WebSockify with Doppio. If a user wants WebSockify, they should drop it into the doppio.js directory and we will 'do the right thing'.

[jvilk]

Or maybe they should:

• Drop it into the doppio.js directory.
• Include it into their page.

Then we don't have to do anything but detect the WebSock object provided by WebSockify.

[perimosocordiae]

I'm in favor of the latter, perhaps with a configurable WebSock parameter somewhere that defaults to null. I'm not a huge fan of changing behavior based on whether an arbitrary value is defined with the name WebSock.

[jvilk]

How else should we test for WebSockify? Testing for global objects is how you detect whether or not things are present in the browser world.

[jvilk]

Unless you mean check once and set a bool. I'm all for that.

[perimosocordiae]

I mean we can pass in the WebSock object to some constructor somewhere, instead of testing for its presence.

[jvilk]

Ah, gotcha. Probably during JVM instantiation or something. I'll consider it!

[jvilk]

The change I made successfully defines the Websock object in WebSocket-enabled and non-WebSocket-enabled browsers.

The next step is to:

• Make Websock part of the constructor for e.g. JVM/runtime state.
• Ensure networking programs have a relevant error message when networking isn't available.

[hanyuei]

@jvilk

I am trying to run a Java program using some classes in java.net package ( mainly class java.net.URL and java.net.URLClassLoader ) in doppiojvm, i got some error.

Uncaught ReferenceError: Websock is not defined
  java_net_PlainSocketImpl.socketCreate(Z)V  @ java_net.ts:169
  Method.code  @ methods.ts:293
  NativeStackFrame.run  @ threading.ts:295
  JVMThread.run  @ threading.ts:671
  (anonymous function) @ threadpool.ts:83
  i @ main.ts:158

I guess it's related to this issue, and if i should do something when doppio init.

[jimfb]

@CoderRooftrellen Just created a related issue: https://github.com/plasma-umass/doppio/issues/418

[jvilk]

I haven't tested the net code in awhile, so it could be broken. I'll take a look once I fix the build issues.

[hanyuei]

@jvilk Thanks.

[jvilk]

I ran out of time today since the build issues took awhile. It's on my todo list for tomorrow.

[hrj]

@CoderRooftrellen For the specific issue you mention "Websock is not defined", the solution I think is to include the script from doppio/vendor/websockify/websock.js on the page, before starting the doppio-jvm.

@jvilk However, after doing that, I see another error:

Uncaught Error: Assertion failed: Int value is out of bounds: 4026531841
assert @ assert.ts:8
validateReturnValue @ threading.ts:1231
JVMThread.asyncReturn @ threading.ts:1035
Opcodes._return_32 @ opcodes.ts:1153
BytecodeStackFrame.run @ threading.ts:254
JVMThread.run @ threading.ts:800
(anonymous function) @ threadpool.ts:83
i @ browserfs.min.js:8

[jimfb]

@hrj flatThrwoableToJs is spelled wrong, did you mean flatThrowableToJs? Also, That's not doppio code :P.

[hrj]

@jimfb Hawkeye! Yeah, the second error was not relevant to doppio. I have edited it out.

[jvilk]

I'm working on this in #462.