Binary event

[flowersinthesand]

Derived from cettia/cettia-protocol#9

With this feature, you will be able to exchange events whose data is binary without binary-to-text conversion.

• Find MessagePack JavaScript implementation
• Implement the default behavior of send method

[flowersinthesand]

msgpack-lite looks the best as MessagePack JavaScript implementation. It is available on browser and Node.js. But, it's too big (37KB minified, 11KB gziped) to include it to cettia.js so those who want to handle binary on browser should include msgpack-lite manually and it should be noted in documentation.

var msgpack = require('msgpack-lite');
var obj = {
  text: "Donghwan Kim",
  binary: new Buffer("Donghwan Kim")
};

var bytes = msgpack.encode(obj);
console.log('[' + new Int8Array(bytes).join(', ') + ']');
console.log(msgpack.decode(bytes));

[-126, -92, 116, 101, 120, 116, -84, 68, 111, 110, 103, 104, 119, 97, 110, 32, 75, 105, 109, -90, 98, 105, 110, 97, 114, 121, -60, 12, 68, 111, 110, 103, 104, 119, 97, 110, 32, 75, 105, 109]
{ text: 'Donghwan Kim',
  binary: <Buffer 44 6f 6e 67 68 77 61 6e 20 4b 69 6d> }

Note that the first line from the result, new Int8Aray(bytes), is the same with one in cettia/cettia-java-server#6 (comment)

[flowersinthesand]

On Node, to traverse the given object to check if it contains binary, we can use traverse.

var traverse = require("traverse");
var hasBinary = data => traverse(data).reduce((hasBuffer, e) => {
  return hasBuffer || Buffer.isBuffer(e);
}, false);

console.log(hasBinary("Donghwan Kim"));
console.log(hasBinary(new Buffer("Donghwan Kim")));

false
true

Unfortunately, traverse module is somewhat big to embed in cettia.js. As a trick on browser, using JSON.stringify's replacer option, it's possible to detect if the given object has binary without importing an external module.

var hasBinary = data => {
  var ArrayBuffer = window.ArrayBuffer;
  if (!ArrayBuffer) {
    return false;
  }

  var hasView = false;
  JSON.stringify(data,  (key, value) => {
    hasView = hasView || ArrayBuffer.isView(value);
    return value;
  });
  return hasView;
};

console.log(hasBinary("Donghwan Kim"));
console.log(hasBinary(new TextEncoder().encode("Donghwan Kim")));

false
true

Anyway, if it turns out that it has binary, msgpack.encode should be used and if not JSON.stringify should be used to serialize an event.

[flowersinthesand]

• Add explanation about binary to socket.send method
• Add explanation about binary to transport.send method
• Load msgpack in jsbin example
• Send binary data in jsbin example

[flowersinthesand]

• Update Node.js compatibility

[flowersinthesand]

Modified example - http://jsbin.com/xakovoguqe/edit?html,js,console

[flowersinthesand]

In d8576e7 commit, a condition to determine if the current environment is Node.js, typeof exports !== "object", is used too much. It would be better to extract Node.js part so-called node.js and load it in only Node.js environement for performance and size.

[flowersinthesand]

JSBin updated to load TextEncoder fallback as well - http://jsbin.com/qaqetibufi/edit?html,js,console

[flowersinthesand]

An explanation about TextEncoder is added - http://jsbin.com/ruquvasevo/edit?html,js,console

[flowersinthesand]

The example is updated http://jsbin.com/votuzakaro/edit?html,js,console