yablo

Installation

Prerequisites: python 2.7; redis server running; btcd operating on testnet or mainnet; dev packages for python, libffi, and libssl (apt-get install python-dev libffi-dev libssl-dev)

For yablo itself:

pip install -r requirements.txt -U
python setup_yablo.py

You may want to adjust yablo.cfg for your environment.

Running

supervisord

You may want to adjust supervisord.conf for your environment. Using supervisord is optional and running everything in the same machine is good for testing and checking how it works.

The command above will start 6 processes, one for each service present in yablo. If you are not interested in answering blockchain queries, then supervisorctl stop api-query will stop it. If you want to temporarily disable the API, then supervisorctl stop api:* does that. If you need to stop processing events, supervisorctl stop evt:evt-process.

Overview

yablo is a backend system for handling blockchain events. At this moment, its main purpose is to act as a notifier for new blocks and new transactions.

Notifications are sent as JSON POST requests to registered webhooks, which are referred as callbacks. To register a webhook, a HTTP request needs to be sent to the front server, which redirects the request to the watch server, which then records the subscription.

Consult the wiki for more information. Improvements to the documentation and code are very welcome!

Sample callbacks

The following callback was sent to a subscriber that was watching for new transactions involving the address "n3vp66W5kuMGARYxNQkWaDuMgz5mdUrU4b". In this case, a callback was fired because the transaction spent an earlier output that involved the address specified.

{
  "id": "34f42ccc-94bb-40b2-baea-59aeb294cd2f",
  "type": "address",
  "address": "n3vp66W5kuMGARYxNQkWaDuMgz5mdUrU4b",
  "origin_time": 1423586417,
  "data": {
    "event_id": "aa7390f0-877a-4945-a92d-2bd4ecd55595",
    "txid": "9643a428800fbbc0....",
    "block_hash": null,
    "confirmations": 0,
    "input": [
      {
        "address": ["n3vp66W5kuMGARYxNQkWaDuMgz5mdUrU4b"],
        "value": 45999406
      }
    ],
    "output": [
      {
        "address": ["n34tHk1PMr17jR5iTaEoRacBrqfErt96qL"],
        "value": 3991893
      },
      {
        "address": ["mrDhESUMK6zVWFNmKomqkhnNmFtRZ1z2q8"],
        "value": 41997513
      }
    ]
  }
}

The full txid is included in callbacks, in the sample above it was shortened to fit. The same id will be used for every callback involving a specific condition for a specific subscriber, the event_id will change for each callback. Details about a specific callback are always in the data field.

New blocks

For new block events, the following format is used in callbacks:

{
  "data": {
    "block_hash": "000000001c8d59223069...",
    "difficulty": 1,
    "event_id": "50952e8b-5216-4a52-a7b7-dc35cae3781d",
    "height": 323748,
    "previousblockhash": "000000007f357d4d7cee...",
    "time": 1424629657,
    "tx": [
      "f1fa694ccf4b601738ce0261cc8741c65b0dbdf5fdb3abb5b62553d172c83ed0",
      "d1edcb76b40a111609c6034223a3a992c57e5e081048e980b72bc217560c1798",
      "a5ddb87e40bcf33d120b031ac76d763ae3ae7e021c20ebf4035fe0dc5664e186",
      "cd59e27321161789966f539d9768b1b379e72b3c9b9e20f36bce55d4e6d8b344",
      "7066eec4f1411a6b8324bf345bbd949b7649f7b5160b6f7c4a1ff263009b3adc",
      "c04ff9a2e887321326fa58a71c04afb6f3e3de2b5c80b0dd939d4cab93ecf729",
      "b1e3953b44e6ab8ef0022d51fc91bad2fd2cb0cb50df8879d74352e0c4faea45"
     ]
  },
  "id": "4ec8dd51-b72e-4690-8a93-7a9783f44084",
  "origin_time": 1424623707,
  "type": "newblock"
}