Write a nice new man page in AsciiDoc

Taking some preliminary steps for inclusion in Linux distributions.

The help message has been slightly improved and the README extended,
with part of it now residing in the man page.

One less GNU dependency, for what it's worth.

1 files changed, 183 insertions, 0 deletions

diff --git a/json-rpc-shell.adoc b/json-rpc-shell.adoc
new file mode 100644
index 0000000..20b1f8c
--- /dev/null
+++ b/json-rpc-shell.adoc
@@ -0,0 +1,183 @@
+json-rpc-shell(1)
+=================
+:doctype: manpage
+:man manual: json-rpc-shell Manual
+:man source: json-rpc-shell {release-version}
+
+Name
+----
+json-rpc-shell - a simple JSON-RPC 2.0 shell
+
+Synopsis
+--------
+*json-rpc-shell* [_OPTION_]... _ENDPOINT_
+
+Description
+-----------
+The _ENDPOINT_ must be either an HTTP or a WebSocket URL, with or without TLS
+(i.e. one of the _http://_, _https://_, _ws://_, _wss://_ schemas).
+
+*json-rpc-shell* will use it to send any JSON-RPC 2.0 requests you enter on its
+command line. The server's response will be parsed and validated, stripping it
+of the protocol's noisy envelope.  At your option, it can then also be
+pretty-printed, rendered with adjustable syntax highlighting, or even piped
+through another program such as the *less*(1) pager or the *jq*(1) JSON
+processor.
+
+Usage
+~~~~~
+Three things may appear on the internal command line, in a sequence.  The first
+one must always be the name of the JSON-RPC method to call, as a bare word,
+separated from the rest by white space.  Following that, you may enter two kinds
+of JSON values.  If it is a string, a number, or a null value, it is taken as
+the "id" to use for the request.  If it is an object or an array, it constitutes
+the method parameters.  Booleans may appear in neither.
+
+The response to the method call may be piped through external commands, the same
+way you would do it in a Unix shell.
+
+Exit the program by pressing C-c or C-d.  No special keywords are reserved for
+this action as they might conflict with method names.
+
+Options
+-------
+Controlling Output
+~~~~~~~~~~~~~~~~~~
+*-p*, *--pretty*::
+	Pretty-print responses, adding spaces and newlines where appropriate
+	to improve readability.
+
+*--color* _WHEN_::
+	By default, when the output of the program is a terminal, JSON responses
+	are syntax-highlighted.  This corresponds to the _auto_ setting.  You may
+	also set this to _always_ or _never_.  In either case, color is never
+	applied when piping to another program.
+
+*-v*, *--verbose*::
+	Print raw requests and responses, including the JSON-RPC 2.0 envelope.
+
+*-d*, *--debug*::
+	Print even more information to help debug various issues.
+
+Protocol
+~~~~~~~~
+*-a*, *--auto-id*::
+	Choose message IDs automatically, in an increasing sequence.  Normally you
+	need to enter the ID on the command line manually, so as to distinguish
+	notifications from other requests.  Even with this option enabled, you can
+	still specify the ID, if you wish.
+
+*-t*, *--trust-all*::
+	Trust all SSL/TLS certificates.  Useful in case that the certificate is
+	self-signed, or when the CA isn't in your CA store.  Beware that this option
+	is about as good as using plain unencrypted HTTP.
+
+*-o*, *--origin* _ORIGIN_::
+	Set the HTTP Origin header to _ORIGIN_.  Some servers may need this.
+
+Program Information
+~~~~~~~~~~~~~~~~~~~
+*-h*, *--help*::
+	Display a help message and exit.
+
+*-V*, *--version*::
+	Output version information and exit.
+
+*--write-default-cfg*::
+	Write a default configuration file, show its path and exit.
+
+Files
+-----
+_~/.config/json-rpc-shell/json-rpc-shell.conf_::
+	The configuration file, in which you can configure color output and
+	CA certificate paths.  Use the *--write-default-cfg* option to create
+	a new one for editing.
+
+_~/.local/share/json-rpc-shell/history_::
+	All your past method invocations are stored here upon exit and loaded back
+	on start-up.
+
+Notes
+-----
+Editing
+~~~~~~~
+While single-line editing on the command line may be satisfactory for simple
+requests, it is often convenient or even necessary to run a full text editor
+in order to construct complex objects or arrays, and may even be used to import
+data from elsewhere.  You can launch an editor for the current request using
+the M-e key combination.  Both *readline*(3) and *editline*(7) also support
+multiline editing natively, though you need to press C-v C-j in order to insert
+newlines.
+
+WebSockets
+~~~~~~~~~~
+The JSON-RPC 2.0 specification doesn't say almost anything about underlying
+transports. As far as the author is aware, he is the only person combining it
+with WebSockets.  The way it's implemented here is that every request is sent as
+a single text message.  If it has an "id" field, i.e. it's not just
+a notification, the client waits for a message from the server in response.
+Should any message arrive unexpectedly, you will receive a warning.
+
+There is no support so far for any protocol extensions, nor for specifying
+the higher-level protocol (the "Sec-Ws-Protocol" HTTP field).
+
+Bugs
+----
+The editline (libedit) frontend is more of a proof of concept that mostly seems
+to work but exhibits bugs that are not our fault.
+
+Examples
+--------
+Running some queries against json-rpc-test-server, included in the source
+distribution of this program (public services are hard to find):
+
+Pretty-printing and Manual IDs
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+```
+$ json-rpc-shell -p ws://localhost:1234
+json-rpc> date 1
+{
+  "year": 2020,
+  "month": 9,
+  "day": 5,
+  "hours": 2,
+  "minutes": 23,
+  "seconds": 51
+}
+```
+
+Notification With a Parameter
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Notifications never produce a response, not even when the method is not known
+to the server:
+
+```
+$ json-rpc-shell ws://localhost:1234
+json-rpc> notify {"events": ["conquest", "war", "famine", "death"]}
+[Notification]
+```
+
+Piping In and Out
+~~~~~~~~~~~~~~~~~
+GNU Readline always repeats the prompt, which makes this a bit less useful
+for invoking from other programs:
+
+```
+$ echo 'ping | jq ascii_upcase' | json-rpc-shell -a ws://localhost:1234
+json-rpc> ping | jq ascii_upcase
+"PONG"
+```
+
+Reporting Bugs
+--------------
+Use https://git.janouch.name/p/json-rpc-shell to report bugs, request features,
+or submit pull requests.
+
+See Also
+--------
+*jq*(1), *readline*(3) or *editline*(7)
+
+Specifications
+~~~~~~~~~~~~~~
+https://www.jsonrpc.org/specification +
+https://www.json.org