In this presentation filmed during QCon London 2008, Markus Voelter tried to convince the audience that writing a textual external DSL is fairly straightforward and simple. He took them through the steps needed to create a textual DSL from defining the grammar to processing a domain model.
Watch: Textual DSLs Made Simple (1 hour).
Markus started his presentation with an introduction to DSLs, what they are, how they can be categorized and pointing to the strengths and weaknesses of each category. His demonstration focused on a textual external DSL built using the Eclipse Modeling Framework.
After the introduction, Markus showed how to define a grammar for the DSL using the EBNF format in an Xtext editor which provides code completion and constraints checking for the grammar. He also showed how to customize the grammar editor in order to provide constraints checking, syntax highlighting, code completion, debugging and others. Markus presentation ends with a domain model being created and processed.