I’m working on a new plugin for nodeos: https://github.com/cc32d9/eosio_zmq_plugin
It’s doing approximately the same as account history plugin, but pushes the history events outside of nodeos into ZMQ PUSH socket. Also apart from transaction details, it reports actual balance of involved accounts in liquid EOS, staked EOS, RAM usage, and I will also add other tokens too.
The main purpose is to store the account histories in an SQL database, and run reports against this data. The history_plugin is storing all history events in the process shared memory, and it grows at 2GB per day. A standard database engine, like MariaDB, will handle the data more efficiently. Also old historic data can be truncated easily, because the plugin exports the actual currency balance information for every transaction.
But in general, this thing can be used for anything. For example, a gateway between two EOS blockchains can be built. Or a true random number generator would receive requests through such an interface, and send random numbers back to the blockchain.
