Pushkin Worker

Pushkin workers interface between RabbitMQ and database(s). A worker is created like this:

import pushkinWorker from 'pushkin-worker';

const workerOptions = {
  readQueue: 'myexp_quiz_dbread',
  writeQueue: 'myexp_quiz_dbwrite',
  taskQueue: 'myexp_quiz_taskworker',
  amqpAddress: process.env.AMQP_ADDRESS
};

const myWorker = new pushkinWorker(workerOptions);

The queues are the respective RabbitMQ queues to listen on. They should match the names of the queues the API for this experiment is sending on. amqpAddress is a connection string for RabbitMQ and is provided by default in a worker’s Docker environment via pushkin prep.

init

Arguments: None

Returns: Promise. Resolves upon connection to RabbitMQ.

handle

Arguments:

  • method : string

    Name of RPC method to associate with this function (below).

  • handler : function

    Function to call when this method (above) is called. The value is sent back along the same queue it was received on. Receives a session id, data sent in the rpc call, and the parameters of the request to the API server as defined in the Express framework.

Returns: None

useDefaultHandles

Arguments:

  • DB URL : string

    Connection string for this experiment’s main database.

  • table prefix : string

    The prefix to assume for default table names in the database. Same as shortName in the experiment’s config.yaml by default.

  • transaction options : { url : string, tableName : string, mapper : function }

    An optional argument to enable logging transactions.

    • url is the connection string for the transaction database.
    • tableName is the name of the table in this database to log transactions in.
    • mapper is a function of string -> object. It’s given an SQL query string (representing what was run on the main database) and should return an object with fields and values matching what to insert into the transactions table.

Returns: None

start

Arguments:

  • something : type

    Description

Returns: something