Kdwatch

Auto-formatting, auto-reloading display of formatted kramdown-rfc document in browser

$ pip3 install --upgrade xml2rfc
$ gem update
$ gem install kdwatch

• For some reason, the initial gem install takes a couple of minutes, during the first few of which it may seem nothing happens.
• If the above pip3 (or pip) doesn't work, no problem: in a pinch, kdrfc will use the IETF web service for xml2rfc processing (but that may be a bit slower).
• Depending on system configuration, add sudo on the pip/gem commands (but don't if it isn't actually needed).

• Open a separate terminal window/screen.
• Go to a directory that has a single draft-*.md (or select one by specifying the markdown file name on the command line) and run:

$ kdwatch

• After about 10 seconds, a browser will open (or an error message will pop up with the URL to use, which depends on the options given, but defaults to http://127.0.0.1:7991/).

Now, whenever you do an editor save of the kramdown-rfc markdown file, kdwatch auto-formats and, after a couple of seconds(*), you see an updated HTML in the browser without pressing buttons or switching windows.

You will need to keep the kdwatch terminal/screen open to see potential error messages, e.g., if you break the markdown in some way. (The author uses an Emacs "Async Shell Command" buffer for that.)

(*) The latency depends on your computer and a bit on the size of the file, say, around 1.6 s for my Intel Mac, 0.8 s for my M1 Mac.

There can only be one kdwatch active on each host and port. You will need to specify a different port (or host!) to run more than one kdwatch at the same time.

• -p port to select a specific port number
• -1 to 6 as a shortcut for -p 7991 to -p 7996 (must be last option because of an idiosyncrasy of the optionparser library)
• if no port number is given, kdwatch will hunt for a port number that doesn't have a listener, starting with 7991.

kdwatch has two flags to simplify handling servers that might be accumulating on one host/port:

• -e to kill (SIGINT) any current holder of the port given and exit
• -r to do this, and to start a new instance as well

So the most likely use is going to be:

kdwatch

to start a new server on a new port number.

These tend to accumulate a bit, so sometimes you'll want to replace an existing one (here: port number 7992):

kdwatch -r2

If your drafts are weirdly named or you need to select one out of many

kdwatch -r5 weird-draft.md

The default port number was chosen after RFC 7991, the initial (no longer really authoritative) version of the v3 RFCXML specification, and the port shortcuts 1 to 6 point to this and further RFCs from this series. (7997 is a particularly lame RFC, so it cannot be chosen by a shortcut [actually: this port is already registered for something else].)

kdwatch essentially is a web server and can listen on any host interface you might have:

• -o host to select an interface address on the serving host (default: 127.0.0.1)
• -i as a shortcut for -o :: (i stands for "on the Internet")

Unless used on 127.0.0.1 (or ::1), kdwatch is accessible to anyone who can access your laptop over IP. That may be a security problem -- do not specify a non-local interface unless you know you are not “on the Internet” (or trust the way I cobble together software). If you are, maybe kdwatch -e before going there!

The fun thing with the -i option is that you can replace the local URL by filling in the hostname of the laptop and use the resulting URL on a different browser (e.g., http://mylaptop.local:7991 on your iPad or another laptop), and save some screen real-estate on your laptop. With a globally routable address, kdwatch even can be used for joint viewing in a team.

The kds tool can list active local (127.0.0.1) kdwatch servers and optionally quickly open the page for a selected kdwatch server.

Usage: kds [options] [match...]
Version: n.m.l (from kdwatch)
    -v, --version                    Show version and exit
    -h, --help                       Show option summary and exit
    -f, --from=NUM                   Search from port number (7991)
    -t, --to=NUM                     Search to port number (7999)

$ kds
http://127.0.0.1:7991  Packed CBOR
http://127.0.0.1:7992  Concise Problem Details For CoAP APIs
$ kds prob
http://127.0.0.1:7991  Packed CBOR
http://127.0.0.1:7992  Concise Problem Details For CoAP APIs
(...web page http://127.0.0.1:7992 opens...)
$

Any match arguments are concatenated with spaces; for servers that offer a page with the match string in the title (case insensitive), a window is opened in the default browser.

This has only been tested on macOS and briefly on Linux. No idea about WSL. There is very little error handling yet, so restarts of the tool may be required, or sometimes reloading in the browser (CMD-R/F5) is all that is needed.

If you try it, please send feedback (and, in case of an error, all output on the kdwatch terminal window, please).

Bug reports, pull requests, or simple suggestions are welcome on GitHub at https://github.com/cabo/kdwatch, e.g., simply submit an issue or send me mail.

The gem is available as open source under the terms of the MIT License.