The real trick is getting updates back to your page asynchrononously as the child process generates them. Yes, you could have them happen only when the browser user hits a refresh button, but that's not terribly effective.
What about <meta/>-refresh?
AFAIK every browser understands this. Sure enough, it's just kind of a mechanized button-press and occurs independent of data-changes/-updates, but its a viable solution.

regards,
tomte

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Edit: added second sentence.