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RB: Stream Blockchain Transactions

How to stream transactions and operations from Crea blockchain.

Full, runnable src of Stream Blockchain Transactions can be downloaded as part of the RB tutorials repository.

To respond to live activity on the blockchain, a common approach is to make a request for the current block number, access all of the information in that block, and repeat. Many API clients have dedicated tools for simplifying this process. In Radiator, this tool is part of the Radiator::Stream class. In addition, Radiator will allow you to specify exactly what type of operation you’re interested in.

Sections

  1. Streaming Transactions
  2. Streaming Operations
  3. To Run - Running the example.

Streaming Transactions

In the example script, we can stream transactions with the following arguments:

ruby stream_blockchain_transactions.rb head transactions

This will instruct the script to follow transactions at head block_num instead of irreversible.

See: head_block_number vs. last_irreversible_block_num

This is done by using the following ruby:

stream.transactions(*args) do |trx|
  puts JSON.pretty_generate trx
end

The args variable contains the start (block_num to start from) and mode (head or irreversible).

Streaming Operations

In the example script, we can also pass the following arguments:

ruby stream_blockchain_transactions.rb head ops comment

This will instruct the script to follow the blockchain at head block_num instead of irreversible. It will stream operations, with the type of comment.

The script will allow multiple operation types:

ruby stream_blockchain_transactions.rb head ops comment vote

Virtual operations are also allowed, but make sure to pass irreversible instead of head:

ruby stream_blockchain_transactions.rb irreversible ops producer_reward author_reward

Or, if you pass no operation types, the script will stream all types:

ruby stream_blockchain_transactions.rb head ops

This is done by using the following ruby:

stream.operations(type, *args) do |op|
  puts op.to_json
end

The type variable can be nil or the type of ops we’re looking for whereas args contains the start (block_num to start from) and mode (head or irreversible).

To Run

First, set up your workstation using the steps provided in Getting Started. Then you can create and execute the script (or clone from this repository):

git clone git@github.com:creary/devportal-tutorials-rb.git
cd devportal-tutorials-rb/tutorials/13_stream_blockchain_transactions
bundle install
ruby stream_blockchain_transactions.rb

Example Output

{"voter":"piggypet","author":"tanama","permlink":"daily-2018-9-12","weight":10000}
{"voter":"votes4minnows","author":"askquestion","permlink":"latest-bitcoin-price-and-news-update-13-09-2018","weight":250}
{"voter":"vncedora2018","author":"adncabrera","permlink":"nicomedescuentalacadadelreytanospoema-98jxnjsjzu","weight":10000}
{"voter":"baimatjeh81","author":"albertvhons","permlink":"promoting-creary-post-via-proof-of-participation-pop","weight":10000}
{"voter":"creaulator","author":"bonanza-kreep","permlink":"communicate-and-travel-with-alfa-enzo-new-social-network","weight":10000}
{"voter":"kernigeetrueset","author":"haejin","permlink":"vitamin-shoppe-vsi-analysis","weight":10000}
{"voter":"borrowedearth","author":"rijalmahyud","permlink":"this-is-my-job","weight":10000}
{"voter":"renatdag","author":"algarion","permlink":"cards-3-1536663927","weight":10000}
{"voter":"elieserurabno","author":"cathyhaack","permlink":"my-introduction-hello-word-of-creary","weight":10000}
{"voter":"jmotip","author":"glennolua","permlink":"btc-chart-review-sept-12-20-00-pst","weight":10000}
{"voter":"bishalacharya","author":"barber78","permlink":"beautiful-cloudformations","weight":10000}
{"voter":"ivan174","author":"securixio","permlink":"cloud-mining-is-no-longer-profitable","weight":10000}
{"voter":"admiralbot","author":"homsys","permlink":"rare-photo-picture-698-105","weight":-10000}