Handling HTTP POST requests in Livelink, Part One

I recently found myself needing to handle HTTP POST requests in Livelink. I could control the Livelink URL the request was sent to, but I could not control the POST body. There were two parts to the challenge, and one had a happy answer, whilst the other did not.

First, I created a new Livelink module and orphaned a request handler. In this particular case, I orphaned WebDsp:WebDsp Root:RequestHandler because I did not want or need a Livelink login. I then tested submitting the HTTP POST using a form like this one:

<form method="POST"
  action="/Livelink/livelink.exe?func=myhandler">

To my surprise, the request was not sent to my handler. I was instead sent to the Livelink login form with a nextURL pointing at func=llworkspace, i.e., the default request handler.

It turns out that Livelink ignores query parameters in the URL on a POST request. When my request got to the Dispatch function, there was no visible "func" parameter, so the default request handler was called.

The solution is to add a PathInfoHandler, and embed the request for myhandler in the path info:

<form method="POST"
  action="/Livelink/livelink.exe/mypathhandler">

I orphaned WebDsp:WebDsp Root:PathInfoHandler and overrode the 0 Setup script to contain:

.fReplacementArgs = {{ 'func', 'myhandler' }}
.fPathInfoName = 'mypathhandler'

So now Livelink sees the /mypathhandler in the URL path info, and infers a func=myhandler query parameter from that. (The use of two different names is completely optional, and I think undesirable. I have used them only to make the distinction clear.)