Enable the bitcoin rpc server to return structured information about the rpc commands it accepts, such as parameters, datatypes, requiredness and maybe a description or parameter bounds
A static example of this can be found here: https://github.com/d3rrial/bitcoin/blob/getrpcinfo_rpc_command/src/rpcserver.cpp
Ideal would be something more dynamic, so that developers, should rpc methods be added or removed don't have to crawl through that list of rpc commands.
The only drawback that I see is that bitcoin-cli (and other RPC command-line clients) would effectively have to do two roundtrips to the server. Once to get instructions on how to convert the command-line parameters to JSON, and once to do the actual command.
(edit: duh, caching could be used, HTTP solved this)
That's the tradeoff, save round-trip time by storing it yourself in the RPC client or save memory by requesting a list containing the instructions.
The one advantage this method would have over RPC clients keeping their own lists, if changes were made to the RPC Server clients would automatically be compatible, as long as the rpcinfo was also updated accordingly.
This wouldn't break existing RPC applications, but it could expand them. Consider this case: An RPC client stores it's own list of RPC commands, but due to some changes to the rpc server a client rpc command that was formerly valid in this way is now invalid and consistently produces an error, even though the user uses correct input. The client could send a getrpcinfo request to the rpc server and (either temporarily or permanently) adapt it's own rpc command list
XBMC's JSONRPC.Introspect API sounds interesting here. It offers introspection and self-documentation (so it's like our 'help' system but machine-parseable).
http://wiki.xbmc.org/index.php?title=JSON-RPC_API/v3#JSONRPC.Introspect
This has even been used to auto-generate client-side libs for static programming languages such as C#: https://jsonrpcgen.codeplex.com/ . I'd say this is exactly what we need. There is not a standard for JSON-RPC introspection as such, but this is the second-best thing: an existing implementation with tools already available.
Is anyone working on this? I suggest we close as an up-for-grabs issue if it's not actively being worked on.
This can be easily implemented with RPCMan (or RPCHelpMan)