ipc-proxy0-pmb

Convenience wrapper for child_process.fork

API

This module exports an object with these methods:

.spawn(libs[, spawnOpts][, then])

Spawns an IPC proxy instance for the module name(s) from libs, which should be a string or an array of strings. Returns the subprocess object, or false if it couldn't fork().

If present, spawnOpts are passed as options to fork().

In case a callback function then is provided, it is called with arguments (error, child) on the child's close event. (Actually, the close:nodeback event from package child-exit-nodeback.)

.err2dict(error), .dict2err(dict)

These functions translate between Error objects and plain, JSON-able (dictionary) objects. Currently they're based heavily on the error-to-json package, but implementation may change without notice.

IPC message protocol

• NB: Node v6 IPC channels are JSON-based, so un-JSON-able data may be transformed or discarded. The jsonize-loudfail package can check your data and warn you in advance.

:TODO:

Usage

from test.usage.js:

var logArgs = test.log.args, ipcProxy = require('ipc-proxy0-pmb'),
  child = ipcProxy.spawn('querystring', logArgs('child quit'));
equal(typeof child.pid, 'number');
child.on('msg:result', logArgs('got result:'));
 
test.add(function () {
  child.send({ mtd: 'stringify', ret: 'result',
    arg: [ { Hello: 'World!', foo: 23, bar: 42 }, '/', ':' ] });
  test.log.expect([
    [ 'got result:', 'Hello:World!/foo:23/bar:42' ],
  ]);
});
 
test.add(function () {
  child.send({ mtd: 'parse', ret: 'result', fin: true,
    arg: [ 'Hello=World&foo=23&bar=42' ] });
  test.log.expect([
    [ 'got result:', { Hello: 'World', foo: '23', bar: '42' } ],
    [ 'child quit', false, '{ChildProcess}' ],
  ]);
});
 
test.add(function () {
  var whale = ipcProxy.spawn('/dev/null/404.js', logArgs('whale quit'));
  equal(typeof whale.pid, 'number');
  whale.on('error', logArgs('whale fail'));
  test.log.expect([
    [ 'whale fail', '{Error "IPC proxy child:'
                  + ' Cannot find module \'/dev/null/404.js\'"}' ],
    [ 'whale quit', '{Error "IPC proxy child:'
                  + ' Cannot find module \'/dev/null/404.js\'"}',
      '{ChildProcess}' ],
  ]);
});
 
test.add(function () {
  var whale = ipcProxy.spawn('querystring', logArgs('whale quit'));
  whale.send({ mtd: "method doesn't exist", ret: true, arg: [] });
  whale.on('error', logArgs('whale fail'));
  test.log.expect([
    [ 'whale fail', '{Error "IPC proxy child:'
                  + ' Cannot read property \'apply\' of undefined"}' ],
    [ 'whale quit', '{Error "IPC proxy child:'
                  + ' Cannot read property \'apply\' of undefined"}',
      '{ChildProcess}' ],
  ]);
});
 
test.add(function () {
  var oneshot = ipcProxy.spawn('querystring', logArgs('oneshot quit'));
  oneshot.send({ mtd: 'parse', ret: true, fin: true,
    arg: [ 'Hello=World&foo=23&bar=42' ] });
  test.log.expect([
    [ 'oneshot quit', false, { Hello: 'World', foo: '23', bar: '42' } ],
  ]);
});

Known issues

• needs more/better tests and docs

 

License

ISC