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Kicking off a Pipelex Workflow Project

Creating Your First Pipeline

A pipeline in Pipelex is a collection of related concepts and pipes. Start by creating a PLX file in your project:

tutorial.plx 

domain = "tutorial"
description = "My first Pipelex library"
system_prompt = "You are a helpful assistant."

[concept]
Question = "A question that needs to be answered"
Answer = "A response to a question"

[pipe]
[pipe.answer_question]
type = "PipeLLM"
description = "Answer a question"
inputs = { question = "tutorial.Question" }
output = "tutorial.Answer"
prompt = """
Please answer the following question:

@question

Provide a clear and concise answer.
"""

This creates a simple Q&A pipeline with:

  • A domain called "tutorial"
  • Two concepts: Question and Answer
  • One pipe that transforms a Question into an Answer

The domain property is the most important part of your pipeline file. It groups all your concepts and pipes into a single, easy to read bundle.

Learn More About Domains

Domains are a core concept in Pipelex that organize your pipelines, concepts, and pipes into semantic namespaces. For a comprehensive guide on domains, see Understanding Domains.

See more about designing pipes in Designing Pipelines. See more about concepts in Define Your Concepts See more about domains in Understanding Domains

File Naming Conventions

Consistent naming makes your pipeline code discoverable and maintainable:

PLX Files

  • Use lowercase with underscores: legal_contracts.plx, customer_service.plx
  • Match the domain name when possible: domain "legal" → legal.plx
  • For multi-word domains, use underscores: domain "customer_service" → customer_service.plx

See more about pipelex bundle specification in Pipelex Bundle Specification

Python Model Files

  • It is recommended to name structure files with a _struct.py suffix: legal.plx → legal_struct.py
  • Pipelex will automatically discover and load structure classes from all Python files in your project (excluding common directories like .venv, .git, etc.)

Project Structure

Key principle: Put .plx files where they belong in YOUR codebase. Pipelex automatically finds them.

Topic-Based (Best for organized codebases): 

your-project/
├── my_project/                # Your Python package
│   ├── finance/
│   │   ├── models.py
│   │   ├── services.py
│   │   ├── invoices.plx          # Pipeline with finance code
│   │   └── invoices_struct.py    # Structure classes
│   └── legal/
│       ├── models.py
│       ├── contracts.plx         # Pipeline with legal code
│       └── contracts_struct.py
├── .pipelex/                     # Config at repo root
│   ├── pipelex.toml
│   └── inference/
└── requirements.txt

Centralized (If you prefer grouping pipelines): 

your-project/
├── my_project/
│   ├── pipelines/              # All pipelines together
│   │   ├── finance.plx
│   │   ├── finance_struct.py
│   │   ├── legal.plx
│   │   └── legal_struct.py
│   └── core/
│       └── (your code)
└── .pipelex/

Flat (Small projects): 

your-project/
├── my_project/
│   ├── invoice_pipeline.plx
│   ├── invoice_struct.py
│   └── main.py
└── .pipelex/

Key Points

  • Flexible placement: .plx files work anywhere in your project
  • Automatic discovery: Pipelex scans and finds them automatically
  • Configuration location: .pipelex/ stays at repository root
  • Naming convention: Use _struct.py suffix for structure files
  • Excluded directories: .venv, .git, __pycache__, node_modules are skipped
  • Best practice: Keep related pipelines with their related code