This section covers the fundamental concepts and essential information you need to understand and work with Expressir.

What You’ll Learn

The Core Topics section provides comprehensive coverage of:

  • Expressir Fundamentals - What Expressir is, its architecture, and when to use it

  • EXPRESS Language - Understanding the EXPRESS data modeling language

  • Data Model - How Expressir represents EXPRESS schemas in Ruby

  • Parsers - How Expressir parses different EXPRESS formats

  • LER Packages - High-performance schema packaging and distribution

Topics

Introduction

Learn what Expressir is, its key features, and how it fits into the EXPRESS ecosystem.

Key concepts:

  • Purpose and goals

  • Architecture overview

  • When to use Expressir

  • Comparison with other tools

Getting Started

Get up and running with Expressir quickly with installation instructions and first steps.

You’ll learn:

  • How to install Expressir

  • Basic CLI usage

  • Simple Ruby API examples

  • Next steps for learning

EXPRESS Language

Understand the EXPRESS data modeling language that Expressir parses and processes.

Topics covered:

  • EXPRESS language overview

  • ISO 10303-11 background

  • Key concepts (schemas, entities, types)

  • EXPRESS syntax basics

Data Model

Explore Expressir’s Ruby data model that represents EXPRESS schemas.

Learn about:

  • Model hierarchy and structure

  • Key classes and their relationships

  • Working with the model programmatically

  • Model traversal patterns

Parsers

Discover how Expressir parses multiple EXPRESS formats.

Understand:

  • Parser architecture

  • Supported formats (EXPRESS, STEPmod, EXPRESS XML)

  • Parsing strategies

  • Error handling and recovery

LER Packages

Learn about LutaML EXPRESS Repository (LER) packages for efficient schema distribution.

Explore:

  • What are LER packages?

  • Benefits and use cases

  • Package structure and format

  • Performance advantages

Next Steps

After reading the Core Topics:

  • Try the Tutorials for hands-on learning

  • Consult the Guides for specific tasks

  • Reference the References for detailed specifications

Prerequisites

To get the most from these topics, you should have:

  • Basic Ruby knowledge

  • Familiarity with command-line tools

  • Some understanding of data modeling concepts (helpful but not required)

Reading Guide

We recommend reading the Core Topics in order if you’re new to Expressir:

  1. Start with Introduction to understand what Expressir is

  2. Follow Getting Started to install and try it

  3. Read EXPRESS Language to understand the domain

  4. Study Data Model to work with schemas programmatically

  5. Review Parsers to understand how parsing works

  6. Explore LER Packages for advanced deployment scenarios

If you’re already familiar with EXPRESS, you can skip directly to Data Model to understand how Expressir represents schemas in Ruby.