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Pipes

Pipes are the fundamental processing units in Velvet. Each pipe performs a specific transformation or operation on election data.

Overview​

Pipes are designed to be composable and chainable, allowing complex workflows to be built from simple, focused components. Each pipe:

  • Takes input from a specified directory
  • Performs a specific operation
  • Writes output to a designated directory
  • Logs its execution

Available Pipes​

decode_ballots​

Decodes encrypted ballots into plaintext votes that can be tallied.

Location: /packages/velvet/src/pipes/decode_ballots/

Documentation to be added.

do_tally​

Executes the counting algorithm on decoded ballots to produce tally results.

Location: /packages/velvet/src/pipes/do_tally/

Documentation to be added.

generate_db​

Creates a SQLite database containing the tally results for efficient querying and reporting.

Location: /packages/velvet/src/pipes/generate_db/

Documentation to be added.

generate_reports​

Produces PDF and CSV reports containing election results in human-readable formats.

Location: /packages/velvet/src/pipes/generate_reports/

Documentation to be added.

mark_winners​

Analyzes tally results to determine which candidates have won according to the electoral rules.

Location: /packages/velvet/src/pipes/mark_winners/

Documentation to be added.

vote_receipts​

Generates individual vote receipts that voters can use to verify their votes were counted.

Location: /packages/velvet/src/pipes/vote_receipts/

Documentation to be added.

Pipe Configuration​

Pipes are configured through the Velvet configuration file, which defines:

  • The execution order of pipes
  • Pipe-specific configuration options
  • Input and output directories

Example configuration:

{
  "version": "0.0.0",
  "stages": {
    "order": ["main"],
    "main": {
      "pipeline": [
        {
          "id": "decode-ballots",
          "pipe": "VelvetDecodeBallots",
          "config": {}
        },
        {
          "id": "do-tally",
          "pipe": "VelvetDoTally",
          "config": {
            "invalidateVotes": "Fail"
          }
        }
      ]
    }
  }
}

Implementation​

Each pipe implements the Pipe trait, which defines:

  • exec() - Main execution method
  • input() - Load and validate input data
  • output() - Write results to output directory

This trait-based design ensures consistency across all pipes and makes it easy to add new pipes to the system.