Gavin Andresen - 2011-01-06 18:38:27

I've been reworking my old 'monitorreceived' patch to catch up with the latest JSON api changes, and I'm looking for feedback.

New methods I've already implemented:

• monitorblocks <url> [monitor=true]: POSTs a JSON-RPC notification to <url> when new blocks are accepted.
• listmonitored : returns list of URLs that are monitoring new blocks
• getblock <depth> : Returns information about block at depth <depth>

getblock/monitorblocks give this information (this is one of the -testnet blocks):

The monitor JSON-RPC notification wraps that information with a call to "monitorblock" -- see http://gavinpostbin.appspot.com/15depef for exactly what a notification looks like.

I'm thinking about adding notification for 0-confirmation wallet transactions, too; something like:

monitortx <url> [monitor=true]  : POST to url when wallet transactions (sends and receives) are accepted.

Information posted would be the same as you get from calling gettransaction, and I'll change listmonitored to return lists of { "category" : block/tx, "url" : url }.

Possible reasons NOT to add this to mainline bitcoin:

1. I'm using boost::xpressive (regular expression library) to parse the urls.  Bitcoin is already dependent on lots of other pieces of Boost, and xpressive is compiled as a header-only dependency (no changes to the Makefiles)... but I wouldn't be surprised if using xpressive causes problems on SOME compiler somewhere.

2. POSTing to https: URLs won't work if you're running on Windows (any windows/mingw experts want to take another crack at getting full openssl working?).

3. Related to https/ssl:  if you POST transactions to a non-ssl url, somebody eavesdropping on your packets will be able to figure out which bitcoin addresses belong to you.  This is a potential privacy issue.

As always, feedback, encouragement, and reality-checks are welcome.