MML Overview

Modality Modeling Language (MML) is a declarative language for defining data models in a version-controllable format.

Key Features

• Human-Readable: MML files are text-based and easy to understand
• Git-Friendly: Designed for version control with meaningful diffs
• Declarative: Describe what you want, not how to build it
• Hierarchical: Natural nesting matches your data model structure

File Organization

MML files are organized in a project directory structure:

my-project/
├── modality_project.yaml         # Project configuration
└── modality/
    ├── models/
    │   ├── conceptual/           # Entity relationship models
    │   │   ├── sales.mml
    │   │   └── marketing.mml
    │   ├── logical/              # Source mappings
    │   │   └── mappings.mml
    │   └── physical/             # Physical schema (auto-generated)
    │       └── schema.mml
    ├── products/                 # Data products
    │   └── customer_analytics.mml
    └── estimates/                # Effort estimates
        └── estimates.mml

Basic Example

Here's a simple MML file defining a sales domain:

domain "Sales" {
  color = "#3498db"
  description = "Sales and revenue tracking"

  entity "Customer" {
    type = "entity"
    description = "Customer master data"

    belongs-to "Platform.User"
  }

  entity "Order" {
    type = "entity"
    description = "Customer orders"

    belongs-to "Customer"
  }
}

Block Types

MML supports several block types organized across conceptual, logical, and physical models:

Conceptual Model

Block	Purpose	File Location
domain	Business domains	models/conceptual/
entity	Entities, metrics, and derivations	Inside domains

Logical Model

Block	Purpose	File Location
source	Source systems with entity mappings	models/logical/

Physical Model

Block	Purpose	File Location
physical_model	Database tables, fields, and indexes	models/physical/
table	Table definitions	Inside physical_model
field	Field definitions	Inside tables
index	Index definitions	Inside tables
foreign_key	Foreign key relationships	Inside fields

Data Products

Block	Purpose	File Location
data_product	Data products	products/
report	Reports and dashboards	Inside products
metric	Metrics and calculations	Inside reports

Planning

Block	Purpose	File Location
entity_estimate	Entity development estimates	estimates/
source_estimate	Source integration estimates	estimates/
report_estimate	Report development estimates	estimates/
roadmap	Roadmap configuration	roadmap/
task	Development tasks	roadmap/

Next Steps

• Learn the syntax
• Explore block types
• See examples