Domain-Driven Design

ContentsBooksFree eBooksTraining CoursesVideo CollectionsCommunity ResourcesBlogsSample ProjectsGO.NET (C#/F#)HaskellIdrisJavaScript / TypeScriptJVM languagesPHPLibraries and FrameworksGO.NETDatabases[Elixir](#…

A walkthrough of using EventStorming and other modeling techniques to build a CQRS and Event Sourcing-based prototype for a fictional business domain.

Concrete tools, techniques, and processes to align software architecture with your business domains, organizational design, team topologies, and corporate strategy.

A practical guide for effectively involving all stakeholders in the design of software.A practical guide for effectively involving all stakeholders in the design of software.

Notes by Mark Nijhof from his experiences learning DDD and CQRS from Greg Young. There is an extensive sample project that accompanies this book.

The canonical book that coined the term Domain-Driven Design. Also known as the "Blue Book."

Very good starter book before you read Implementing Domain-Driven Design or Domain-Driven Design: Tackling the Complexity at the Heart of Software.

Real examples written in PHP showcasing DDD Architectural Styles, Tactical Design, and Bounded Context Integration.

Domain-Driven Rails describes 11 techniques (from Bounded Contexts to Event Sourcing) that you can use separately and together in new and old Rails apps to achieve better architecture.

Tackle Software Complexity with Domain-Driven Design and F#.

Tangentially connected to DDD, describes the importance of the Ubiquitous Language and working together with domain experts, along with lots of technical details.

A walkthrough of using Domain-Driven Design with Event Sourcing and CQRS using ASP.NET Core and SQL Server in production.

Tackling complexity in the heart of software by putting DDD principles into practice by Alexey Zimarev.

Also a canonical book presenting a top-down approach to understanding Domain-Driven Design. Also known as the "Red Book."

Learn how to implement DDD, CQRS and Event Sourcing. Understand the theory and put it into practice with JavaScript and Node.js.

The deepest tutorial and explanation about EventStorming, straight from the inventor.

Learn the essential patterns and practices of domain-driven design and how to apply them in your day-to-day work, both in greenfield and brownfield projects.

A software architect’s digest of core practices, pragmatically applied.

Methods for managing complex software construction following the practices, principles and patterns of Domain-Driven Design with code examples in C#.

Shows how to use Domain-Driven Design to avoid security vulnerabilities.

This book distills from the experience of leading teams worldwide effective ways to specify, test, and deliver software in short, iterative delivery cycles. Case studies in this book range from small web startups to large financial institutions, working in many processes including XP, Scrum, and Kanban.

Have you had troubles with versioning an Event Sourced system? Just getting into a new Event Sourced system for the first time? This book is the definitive guide of how to handle versioning over long periods of time.

A quick read exploring the core patterns and principles of Domain-Driven Design, as well as strategies for applying DDD in brownfield projects.

Writing Great Specifications is an example-rich tutorial that teaches you how to write good Gherkin specification documents that take advantage of Specification by Example's benefits.

An infographic on the anatomy of Domain-Driven Design.

Provides end-to-end guidance on building monolithic web applications using DDD, ASP.NET Core, and Azure. eShopOnWeb sample

A book about Pythonic application architecture patterns for managing complexity.

Exploring CQRS and Event Sourcing.

To celebrate the anniversary, we've asked prominent authors in the software design world to contribute old and new essays. With contributions by Martin Fowler, James Coplien, Rebecca Wirfs-Brock, Mel Conway, and many more.

A summary of the patterns and definitions of DDD.

Domain Driven Design Quickly is a short, quick-readable summary and introduction to the fundamentals of DDD.

In this three-part series, Vaughn Vernon walks through some common design pitfalls, discusses the pros and cons of various aggregate modeling choices, and provides rules of thumb to guide modeling of aggregates.

Describes three strategies for getting started with DDD when you have a big commitment to legacy systems.

Discover how a Living Documentation can help you in all aspects of your projects, from the business goals to the business domain knowledge, architecture and design, processes and deployment, even if you hate writing documentation.

An introduction to developing microservices-based applications and managing them using containers. eShopOnContainers sample

A 68 pages long free ebook on what DDD, CQRS and event-sourcing are, and how they fit each other.

This magazine is packed with visionary and practical insights, based on personal, business, and customer experiences to support you on your DDD journey

Visual Collaboration Tools is a book for teams building software. It describes tools that help us in our daily job, and also present field stories from different practitioners.

Online training course from Udi Dahan. Udi's live training schedule can be found here.

Public Workshops by Eric Evans, Alberto Brandolini, Mathias Verraes, Rebecca Wirfs-Brock, Nick Tune, and many more.

public and in-house Domain-driven design workshops from foundation to professional level.

Vaughn Vernon's online training course.

Using our video lessons with Eric Evans, author of the original book on Domain-Driven Design (DDD), teach yourself techniques for evolving practical models that improve your software — not just your documents.

Introduction to DDD, CQRS, and Event Sourcing.

(also in Spanish) - learn the fundamentals of EventStorming. Everything about EventStorming with examples.

These videos include the entirety of Greg Young's DDD, CQRS, and Event Sourcing class.

CQRS and Event Sourcing Koans.

Introduction to Event Sourcing and CQRS.

Domain-Driven Design Fundamentals - Teaches the fundamentals of Domain-Driven Design (DDD) through a demonstration of customer interactions and a complex demo application, along with advice from Eric Evans.Domain-Driven Design in Practice - A descriptive, in-depth walk-through for applying Domain-Driven Design principles in practice.[Modern Software Ar…

Introduction to DDD, fundamentals of CQRS & Event Sourcing for Ruby/Rails developers.

This course will discuss the reasons we use CQRS/ES, what benefits it provides us, but also what it will cost us to use. We will see how CQRS/ES can impact the scalability, consistency, and availability of our application.

Use DDD to decompose a problem domain into manageable parts. Learn how those parts can become the foundation of Reactive Microservices and Reactive Architecture. Free, online, self-paced. Certificate offered upon completion.

Learn how to build event sourced applications in Laravel using Spatie's event-sourcing package. Has 2 hours of video content and an accompanying ebook.

Recordings of talks given at DDD Europe.

Searching DDD returns various talks given by Greg Young, Alberto Brandolini, and Dan North, etc.

A YouTube collection of talks given by Alberto Brandolini on Event Storming.

A vimeo channel focused on DDD and CQRS.

A YouTube collection of various talks given by Greg Young.

Recordings of the talks given at the Explore DDD conference.

A YouTube collection of talks given at KanDDDinsky.

A youtube collection of recorded meetups session from Virtual Domain-driven design

A YouTube collection of webinars focused on DDD in Ruby on Rails

Session from 2017 DevoxxUK on how to define bounded contexts

An active mailing list and an excellent resource to ask questions and learn fine-grained details about DDD/CQRS.

The Google Group to discuss Domain-Driven Design in Spanish.

The place to discuss Domain-Driven Design, CQRS, Event Sourcing, Model Storming, Hexagonal Architecture, Distributed Systems, Reactive... in the context of PHP.

The Google Group to discuss EventStorming.

A collection of articles on Domain-Driven Design in Ruby on Rails

A subreddit for Ruby developers interested in Domain-Driven Design.

A Discord (old Slack) team for those who want to chat about Domain-Driven Design, CQRS, Event Sourcing and sometimes random things. Main channel is language and framework agnostic.

A Discord team about Domain StoryTelling (#domain-storytelling channel) by @hofstef. The homepage is at domainstorytelling.org.

Software Engineering Stack Exchange questions tagged domain-driven-design.

Code Review Stack Exchange questions tagged domain-driven-design.

Stack Overflow questions tagged domain-driven-design.

Advanced Topics in Event Sourcing / CQRS / DDD list compiled and maintaned by @sebastianharko.

Questions tagged domain-driven-design.

A Slack team on DDD, event-sourcing, CQRS and wolkenkit.

awesome list that focuses only on Event Storming.

awesome list that focuses only on Domain Storytelling.

Online meetups with panel discussions, online collaborations and resource sharing.

Domain-Driven Design Heuristics is a community driven site to document and discuss about Design Heuristics.

GitHub's profile of Domain-Driven Design in dynamic languages.

GitHub's profile of Domain-Driven Design Crew.

Context Mapping Cheatsheet and Starter Kit by ddd-crew.

Upcoming live training, events, and user groups across North America.

DDD and software design articles from Mathias Verraes and others.

Helpful development and design advice for .NET developers.

Steve Smith. Pluralsight author and author of DDD Fundamentals course and Microsoft eShopOnWeb sample app.

Weekly curated links related to DDD/CQRS/ES.

Want to learn about CQRS and Event Sourcing? This blog is packed with step-by-step articles to give you a head start.

Being so immersed in finance while still in love with programming, I’m naturally a big fan of Domain-Driven Design by Eric Evans, along with TDD, BDD and agile/XP practices.

I focus on DDD, distributed systems, and any other acronym-centric design/architecture/methodology.

CodeBetter.Com exists in order to help foster awareness of better practices, superior tools, proven methodologies and techniques within the software development community.

Good Enough Software is By Definition Good Enough.

Domain-Driven Design Content on InfoQ.

Inventor of Behavior-Driven Design. Blogs and talks about Event Storming also.

Maintainable code is a business advantage. Creator of Domain Map: The Domain Modeling Tool - Easy And Powerful Domain Driven Design.

Principal Middleware Architect @ Red Hat, open-source enthusiast, committer @ Apache, Cloud, Integration, Kubernetes, Docker, OpenShift, Fabric8.

Pluralsight author. Blogs about software development principles and best practices.

Articles on TechBeacon tagged domain driven design.

Articles under the category Domain Driven Design.

Inventor of Event Storming. Asserting that problems cannot be solved with the same mindset that originated them, Alberto switches perspective frequently assuming the architect, mentor, coach, manager or developer point of view.

Various articles about DDD/CQRS. Implemented Greg Young's SimpleCQRS sample in F#.

Vaughn Vernon understands the unique demands of software development and the challenges you face as you improve your craft in a fast-paced industry.

Various DDD-related articles.

Practical event sourcing.

Excellent articles and talks on Domain-Driven Design.

From the creator of NServiceBus.

From the creator of the MassTransit distributed application framework.

From the CTO and co-founder of Petabridge, developers of the Akka.NET Actor Model framework.

Mostly C#, DDD, and Akka.NET.

Ranting and Programming in Java, Clojure, and JavaScript. Articles tagged under cqrs.

Content by Oasis Digital tagged under cqrs.

Adaptech Solutions blog. Our founder, Adam Dymitruk, debated the merits of CQRS with Greg Young before Greg coined the term. Adam and business partner Robert Reppel are among the leading practitioners of event-sourced microservices.

Several articles about DDD from 2013, which are still relevant.

Software architect, trainer, book author. Author of Microsoft .NET - Architecting Applications for the Enterprise (2nd Edition).

Domain-Driven Design mixed with security, and agile in general. Written as fictional letters to a younger programmer.

DDD & Co. series

Various DDD, CQRS, Event Sourcing related articles from Ruby experts.

DDD series - language, domain, modeling, infrastructure, implementation in PHP

DDD, CQRS, TDD blog posts with code samples in C# .NET

DDD series introduction and talk about how to implement DDD with TypeScript

DDD, BDD, Socio-technical, EventStorming and continuous delivery blogs.

Personal blog about Domain-Driven Design, Visual Collaboration, leadership and organisational design. And other things in between. Curator of Visual Collaboration Tools and host of the Software Crafts Podcast

GlobalAppTesting's engineering blog with materials on practical DDD and CQRS.

Sample app demonstrating the use of Cucumber + GO for a BDD testing approach. Blog post can be found here.

This is an attempt to port the DDD Sample App to idiomatic Go. It can be run in a dockerized mode for previewing the application.

Complete serverless application to show how to apply DDD, Clean Architecture, and CQRS by practical refactoring of a Go project. A full blog series about it can be found at https://threedots.tech/.

Sample DDD application implementing the 4 layers (Domain, Infrastructure, Application and Interface) and considering two domain patterns. There's a blog article written for it here.

Just another sample application implementing the four layers of DDD.

API implementation with full CRUD using a SOLID, Hexagonal Architecture. There is a series of blog post written for it at https://blog.friendsofgo.tech/.

PoC for a patients API using the hexagonal architecture pattern.

A boilerplate project for DDD in Azure using a custom handler and Cosmos DB for event sourcing

solution presents usage of DDD tactical patterns to achieve better readability and expressiveness of the code. Applying DDD patterns together with ubiquitous language closes the gap between language spoken by experts and the team and language used in the code.

Domain Driven Design, CQRS, & Event Sourcing Example using GetEventStore, CommonDomain, NServiceBus, Entity Framework, SQL Server, SignalR.

An event based Micro ERP.

ContosoUniversity on ASP.NET Core with Full .NET Framework.

Sample implementation and comparison of various approaches to building DDD applications. Useful as a baseline to quickly start a DDD .net project.

An idiomatic F# implementation of Domain-Driven Design

(C#) - a .NET skeleton project to introduce the concepts of Domain Driven Design and loosely coupled layers.

Examples of implementation CQRS with Event Sourcing - evolutionary approach (no CQRS, separate models and commands with the same model, separate models and commands with separate models, separate storage engines, event sourcing).

.NET CLI and VS Templates with simple use cases to build scalable applications on top of .net core with architectural best practices (DDD, onion architecture etc).

Email marketing ASP.NET Core MVC and ASP.NET MVC demo app demonstrating CoreDdd usage

Full ASP.NET Core 3.1 application with Clean Architecture, DDD, CQRS and Event Sourcing concepts

Full ASP.NET Core 3.1 reference application from Microsoft showing monolithic deployment architecture

eShop fullstack example featuring catalog, basket, checkout, and order bounded contexts

Example of Domain Driven Design for the game of checkers. There are two files: a scratch file with a series of designs, and a final version.

samples and resources about Event Sourcing and CQRS in .NET. Contains also a self-paced kit of how to built own Event Store

DDD, CQRS, and Event-Sourcing example and contains following technology stack: EventFlow, EventStore, RabbitMQ, MongoDB, PostgreSQL, Docker

Example project that accompanies Mark Nijhof's CQRS book.

Event sourcing implementation sample in F#.

These are the sample Bounded Contexts for C#.NET from the book "Implementing Domain-Driven Design" by Vaughn Vernon.

Modular application built with Clean Architecture and DDD principles which is ready to quickly get splitted into microserves.

Sample code from CQRS Journey.

Full Modular Monolith .NET application with Domain-Driven Design approach.

Starter template for a modular application in Clean Architecture DDD style with synchronous interaction between modules within single transaction. Perfect for ERP applications.

(.Net Core Preview 2) - a N-Layered Architecture Sample Project.

Reactive Trader Cloud by Adaptive Consulting.

.NET Core REST API CQRS implementation with raw SQL and DDD using Clean Architecture.

CQRS without the Plumbing, video.

Greg Young's SimpleCQRS in F#.

Greg Young's "Simplest Thing" CQRS with Event Sourcing project.

Task management system based on .NET Core with DDD, CQRS and Event Sourcing Concepts.

Implementation of basic Todo app via tastejs/todomvc in C#/Typescript with eventsourcing, cqrs, and domain driven design

Haskell todo list reactive application with DDD, CQRS and Event Sourcing, FRP.

Dependently typed implementation of the Domain Modeling Made Functional book. An example project how to formalize Bounded Context and Workflow diagram with dependent types. A NodeJS deployable demo.

A collection of DDD sample applications, such as TodoMVC, a geocaching app, collaborative boards etc.

Example applications built with Booster Framework.

Complete working example of using Domain Driven Design (DDD), Hexagonal Architecture, CQRS, Event Sourcing (ES), Event Driven Architecture (EDA), Behaviour Driven Development (BDD) using TypeScript and NestJS generated using the Bitloops Language (BL).

Demo project to implement the CQRS and Event Sourcing patterns in Scala-Akka.

sample project of a library driven by real business requirements. Modular monolith implemented with the help od DDD, BDD, EventStorming, Example Mapping, CQRS, and more.

DDD-CQRS sample v2.0 project that helps you with starting out advanced domain modeling using Spring, JPA and testing.

"Do It Yourself" DDD workshop and a sample DDD application at the same time. Based on a project managing domain.

A simplified (in memory) example of Event Sourcing and CQRS implementation for Java code (modeled for banking domain use cases).

A pragmatic application of Event Sourcing and CQRS in Java with good references for common related problems, e.g. event ordering and idempotency.

Sample event sourced application with Command Query Responsibility Segregation

These are the sample Bounded Contexts from the book "Implementing Domain-Driven Design" by Vaughn Vernon.

Examples of implementation CQRS with Event Sourcing - evolutionary approach (no CQRS, separate models and commands with the same model, separate models and commands with separate models, separate storage engines, event sourcing).

Sample DDD/CQRS project written in Kotlin.

A concrete sample to go through EventStorming workshop and implement DDD tactical design pattern in Java, apply AWS cloud native services to build up business Event based Coffeeshop scenario.

Sample DDD project using Spring Boot (originally hosted in http://dddsample.sourceforge.net/)

This project demonstrates how you can develop applications with the Jakarta EE platform using widely adopted architectural best practices like Domain-Driven Design (DDD). The code is intended to mirror a non-trivial application that developers in the real work would work on. It attempts to demonstrate first-hand how you can use Jakarta EE to effectively meet practical enterprise concerns such as productivity, agility, testability, flexibility, ma…

Simple DDD + Clean Architecture using Micronaut.

DDD CQRS ADR hexagonal architecture implementation built with PHP 7 and Symfony 5.

A DDD Onion Architecture implementation with Symfony 7 as modulith.

A sample application in PHP built with Symfony 3 and Vue.js.

Sample implementation in PHP.

PHP 7 Version of the cargo sample used in Eric Evans DDD book

Sample project that demonstrates how simple shop cart can look like. Domain objects,Doctrine integration.,TDD,layers,unit testing

DDD, CQRS and Event Sourcing app using Symfony and PHP 8.

Ginkgo builds on Go's testing package, allowing expressive Behavior-Driven Development ("BDD") style tests.

Small BDD framework for GO.

Go testing in the browser. Integrates with go test. Write behavioral tests in Go.

Package godog is the official Cucumber BDD framework for Golang, it merges specification and test documentation into one cohesive whole, using Gherkin formatted scenarios in the format of Given, When, Then.

.NET event sourced domain driven design model via NServicebus and GetEventStore.

Lightweight infrastructure for doing eventsourcing using aggregates.

Akka.NET is a toolkit and runtime for building highly concurrent, distributed, and fault tolerant event-driven applications on .NET & Mono.

Successor of ASP.NET Boilerplate - ASP.NET Core based application framework to create NLayered, Domain Driven Designed web applications with a microservice focused modular architecture

ASP.NET MVC, Web API and ASP.NET Core based application framework to create NLayered, Domain Driven Designed web Applications implementing best practices.

This library helps to create ValueObjects (even with collection properties) with properly implemented equality behavior.

Middleware to handling commands over HTTP; typically used in CQRS applications.

d60 event sourcing + CQRS framework.

Command Query Separation for 🌐ASP.NET Core ⚡AWS Lambda ⚡Azure Functions ⚡Google Cloud Functions 🌐ASP.NET Web API 2

Set of open-source .NET libraries helping with DDD and CQRS, with NHibernate persistence

CQRS on Windows Azure.

Build better applications with Dolittle. An Event Sourced, Microservice platform oriented around DDD with developer productivity and simplicity front and center.

Library and tutorial for how to build CQRS/ES applications, including a BDD style testing framework.

Async/await first CQRS+ES and DDD framework for .NET http://geteventflow.net/.

A library to facilitate communication between CommandService and QueryService. The Idea is when any event occures in commandService, it should be persisted in QueryService in MongoDb.

A set of libraries for CQRS and Event Sourcing, with a Domain-Driven Design flavor.

Postgresql as a Document Database and Event Store for .Net Applications.

Distributed Application Framework for .NET.

Supports request/response, commands, queries, notifications and events, synchronous and async with intelligent dispatching via C# generic variance.

Described in this video: The Beating Heart of CQRS, or Actor-Based Message Routing on the CLR by Paulmichael Blasucci at the New York F# .NET User Group.

A smart set of common classes and implementations to improve your development productivity using .NET (DDD, CQRS, Specification Pattern, MediatR, Validations, Notifications).

A persistence library used to abstract different storage implementations when using event sourcing as storage mechanism.

Service bus for .NET.

Projac is a set of projection libraries that allow you to write projections targetting various backing stores.

An simple,elegant and useful Domain-Driven Design and CQRS framework developed using .NET Core 2.0.

.NET Stream Store library targeting SQL based implementations.

Event Store for Azure Table Storage.

Making it easier to convert strings to/from .NET types.

A simple library for creating applications based on the CQRS pattern with support for attribute routing and hosted handlers. Developed in C# targeting .NET Standard 1.0.

A simple implementation of the Repository pattern for .NET, supporting MongoDB and Entity Framework, extending the model with further utilities (caching, paging, validation, etc.).

The open-source, functional database with Complex Event Processing in JavaScript.

Business event capture and querying framework.

Microservice Native Event Store and Message Store for Postgres. A fully-featured event store and message store implemented in PostgreSQL for Pub/Sub, Event Sourcing, Messaging, and Evented Microservices applications.

Complete platform for Event Sourcing & CQRS.

Command handling middleware for CQRS/ES applications, Pure Functional Data Structures for Aggregates and Process Managers, Point-to-Point message routing, and much more in Elixir (Erlang VM) - All in Actor concurrency model.

Traceable, extendable and minimalist event bus implementation for Elixir with built-in event store and event watcher based on ETS.

CQRS event store using PostgreSQL for persistence.

CQRS implementations in node.js. Includes node-eventstore, node-cqrs-domain, node-eventdenormalizer, node-cqrs-saga.

A CQRS, DDD, and event-sourcing framework for JavaScript and Node.js.

Open-source, 4th-generation, transpiled programming language that helps you write clean code, well-designed systems, and build high-quality software that is testable, auditable and maintainable using DDD and Hexagonal Architecture.

A CQRS, DDD and event-sourcing open-source framework that leverages all the infrastructure and uses high-level abstractions and conventions. It help users build advanved even-driven applications letting them focus on business logic exclusively.

NodeJS web API boilerplate for DDD and Clean Architecture applications.

Reusable artifacts for building applications on top of the Akka platform following CQRS/DDDD-based approach.

Apache Isis is a framework for rapidly developing domain-driven apps in Java.

The axon framework is focused on making life easier for developers that want to create a java application based on the CQRS principles.

A lightweight flexible development framework for complex business architecture based on DDD.

Event sourced aggregates for Java.

The Lagom Framework is a microservices framework for the Java Virtual Machine, with APIs for the Java and Scala languages. It includes an Event Sourcing/CQRS based persistence module.

A set of building blocks that enable you to code business logic according to the Domain-Driven Design (DDD) approach.

a CQRS/ES framework for building cloud applications. Defines Bounded Contexts with their Commands, Events, and Entity states in Protobuf. The backend logic is written in Java, on top of the Proto-generated code. Client code in Java, JS or Dart communicates with the backend via gRPC.

A Modern Reactive CQRS Architecture Microservice development framework based on DDD and EventSourcing.

Broadway is a (PHP) project providing infrastructure and testing helpers for creating CQRS and event sourced applications.

A PHP framework for codefying and building complex applications using Domain-Driven Design, CQRS, and Event Sourcing.

Enables message driven architecture in PHP and provides building blocks to follow DDD and CQRS principles.

Apply a Term Analysis to extract domain terms vs out-of-scope terms in a DDD manner.

Mature, stable Python library for event sourcing and DDD. Supports wide variety of databases, different kinds of orderings of domain events, application level encryption, snapshotting, optimistic concurrency control, and process events. Applications, and entire systems of applications, can be defined independently of infrastructure, and run in different ways (single threaded, multi-threaded, clocked, stepping, multi-process, actor model) and with different infrastructure.

A set of libraries for pluggable business logic components.

Quickly create DDD Python patterns, Event-Based Systems, CRUD applications. Set of Python patterns for database access that support SQLAlchemy, MongoDB, Redis, or Pure Python. PyAssimilator allows you to write code without dependencies, meaning you can switch SQL to NoSQL without changing a single file in your system.

Event Sourcing and Microservices Stack for Ruby. A set of libraries for writing event driven, autonomous services.

Rails Event Store (RES) is a library for publishing, consuming, storing and retrieving events. It's your best companion for going with an event-driven architecture for your Rails application.

11 June 2015.

19 August 2014.

10 May 2007.

29 August 2006.

2012 thru 2016.

13 May 2015.

30 January 2015.

The Leading DDD conference (online during COVID19)

A new event for the CQRS/EventSourcing community

A curated conference for DDD newcomers

Submit your talks to all the DDD user groups at once.

Specific about EventStorming

a knowledge-crunching technique that helps the people involved to familiarize themselves with the domain and work out a model that expresses their shared understanding. Available as a print-out template, as well as open-source online tool, WPS Modeler (source).