This plugin is doing approximately the same as history_plugin, but instead of storing history events in the shared memory database, it pushes them outside of nodeos process via ZeroMQ PUSH socket.

If wildcard filter is enabled for history_plugin, all account history is stored in the same shared memory segment as the blockchain state database. This leads to its rapid growth, up to 2GB per day, and increased risk of node crash because of exceeded memory or disk space. The ZMQ plugin allows processing and storing the history events elsewhere, such as RDBMS with truncation or archiving of old entries.

The PUSH type of socket is blocking, so if nobody is pulling from it, nodeos will wait forever. This is done in order to prevent skipping any action events in the blockchain. The receiver may also route the events to non-blocking types of sockets, such as PUB socket, in order to let other systems listen to events on the go.

1. 32-bit signed integer in host native format (little-endian on most platforms): msgtype=0|1. Zero indicates an action trace, and 1 indicates an irreversible block information. Other values are reserved for future message types.

2. 32-bit signed integer in host native format: msgopts=0. Other values are reserved for future option codes.

3. JSON data.

The JSON data is a map with the following entries:

1. action_trace: action and its corresponding inline actions, like in history_plugin RPC output.

2. block_num: block number.

3. block_time: block timestamp

4. global_action_seq: global running number of the action.

5. currency_balances: array of token balances for all accounts and all currency tokens involved in the action. Each entry is a map with account_name, issuer, and balance keys.

6. resource_balances: array of maps indicating current resources for every account involved in the action, with the keys and values as follows:

• account_name: resource holder account;

• cpu_weight, net_weight: staked CPU and network bandwidth in EOS, multiplied by 10000;

• ram_quota: total RAM owned by the account, in bytes;

• ram_usage: used RAM, in bytes.

Unlike history_plugin, this plugin does not deliver account_action_seq, because that value is calculated internally by the history plugin.

The JSON data is a map with the following fields:

1. irreversible_block_num: irreversible block number.

2. irreversible_block_digest: block hash.

The JSON data is a map with the following fields:

1. invalid_block_num: block number where fork happened. All blocks with higher or equal numbers should be discarded.

This event is pushed to the ZMQ socket preceeding transaction traces belonging to the block. The JSON data is a map with the following fields:

1. accepted_block_num: block number.

2. accepted_block_timestamp: block timestamp.

3. accepted_block_producer: block producer.

4. accepted_block_digest: block hash.

The event is generated on every failed transaction, with the following map structure:

1. trx_id: transaction ID.

2. block_num: block number;

3. status_name, status_int: textual and numeric representation of the failure status.

Transaction status values are defined in "libraries/chain/include/eosio/chain/block.hpp" in EOS suite as follows:

      enum status_enum {
         executed  = 0, ///< succeed, no error handler executed
         soft_fail = 1, ///< objectively failed (not executed), error handler executed
         hard_fail = 2, ///< objectively failed and error handler objectively failed thus no state change
         delayed   = 3, ///< transaction delayed/deferred/scheduled for future execution
         expired   = 4  ///< transaction expired and storage space refuned to user
      };

The following configuration statements in config.ini are recognized:

• plugin = eosio::zmq_plugin -- enables the ZMQ plugin

• zmq-sender-bind = ENDPOINT -- specifies the PUSH socket binding endpoint. Default value: tcp://127.0.0.1:5556.

• zmq-whitelist-account = ACCOUNT -- sets up a whitelist, so that only traces for specified accounts are exported. Multiple options define multiple accounts to trace. If the account is a contract, all its actions (including inline actions) are exported. Also all transfers to and from the account, system actions, and third-party notifications are triggering the trace export.

This plugin depends on:

• Modification in build script EOSIO/eos#5229

apt-get install -y pkg-config libzmq5-dev
mkdir ${HOME}/build
cd ${HOME}/build/
git clone https://github.com/cc32d9/eos_zmq_plugin.git
git clone https://github.com/EOSIO/eos --recursive
cd eos
#
# edit eosio_build.sh according to
# https://github.com/EOSIO/eos/issues/5229
vi eosio_build.sh

# compile EOS suite
LOCAL_CMAKE_FLAGS="-DEOSIO_ADDITIONAL_PLUGINS=${HOME}/build/eos_zmq_plugin" ./eosio_build.sh

# insttall
sudo ./eosio_install.sh

Action onblock in eosio account is ignored and is not producing a ZMQ event. These actions are generated every 0.5s, and ignored in order to save the CPU resource.

System accounts, such as eosio and eosio.token and few others are not listed in currency_balances and resource_balances.

Action tweet in blocktwitter account is blacklisted in order to speed up re-synching with mainnet.

• cc32d9 cc32d9@gmail.com
• https://github.com/cc32d9
• https://medium.com/@cc32d9