This is a tutorial for capturing http requests for modification and/or resubmission at a later date. First, get the environment right:

Now capture the request from this page (use the same procedure wherever else you need to capture the parameters of a form):

You should now see some notification that you're redirecting this page. Write what you want to say, hit submit, and you'll be asked to save a configuration file for the request. Save it, then on the command line execute this:

  % tap run -- load/yaml --:s submit --: dump < request.yml

The request will be submitted and you'll get a printout of the response body. To prove everything worked right, click the close link in the redirection bar and resubmit the form.

Link
Form:

Redirection occurs via the on-click and on-submit callbacks for links and forms, respectively. The existing behavior is preserved, as can be demonstrated below:

  <form action='/capture/say' onsubmit='alert("Form was submitted!")'>
Link with OnClick
Form with OnSubmit: