Selecting Workflows

Some actions apply to a selection of workflow:

sending an event to workflows
pausing or resuming workflows
terminating workflows

Currently, there are 3 ways to select workflows:

Type	`selector` value
by id	`this.select.workflow().withId("<id>")`
by name	`this.select.workflow("<name>")`
by name and tag	`this.select.workflow("<name>").withTag("<tag>")`

This selector value should be used in requests below. For example:

const selector = this.select.workflow("<name>").withTag("<tag>");

For example:

module.exports.handle = function* (...) {
  ...
  // select a workflow
  const selector = this.select.workflow("<name>").withTag("<tag>");
  // send an event to it
  selector.send("<event name>", ...<event data>);
  // pause it
  yield selector.pause();
  // resume it
  yield selector.resume();
  // terminate it
  yield selector.terminate();
  ...
};

The ability for workflows to dispatch new workflows and to be able to communicate between them through events is a very powerful pattern, similar to the actor model.