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Microservice DSL (MDSL)

A Domain-Specific Language (DSL) to specify (micro-)service contracts, their data representations and API endpoints.

Primer — Endpoint Types — API Provider and Client — Tutorial — Tools —Transformations

TL;DR

Microservice Domain-Specific Language (MDSL) abstracts from technology-specific interface description languages such as OpenAPI/Swagger, WSDL, and Protocol Buffers.

If the URI of this page is https://socadk.github.io/MDSL/index, you are looking at the GitHub pages of the next version (technology preview)! Please refer to https://microservice-api-patterns.github.io/MDSL-Specification/index for the latest public open source version.

A First Example

An API with a single endpoint HelloWorldEndpoint that exposes a single operation called sayHello can be modelled as this:

API description HelloMDSLWorld

data type SampleDTO {ID, D<string>} 

endpoint type HelloWorldEndpoint
exposes 
  operation sayHello 
    expecting payload "in": D<int>  
    delivering payload SampleDTO

API provider HelloWorldAPIProvider
  offers HelloWorldEndpoint 
  at endpoint location "http://localhost:8000" 
  via protocol HTTP 
    binding resource HomeResource at "/"
      operation sayHello to POST 
  
API client HelloWorldAPIClient
  consumes HelloWorldEndpoint 
  from HelloWorldAPIProvider
  via protocol HTTP 

These language elements and their motivation are explained in the MDSL Primer.

MDSL Tools

The following tools already support MDSL:

Our Eclipse plugin for MDSL, available from this update site, offers syntax checking highlighting, semantic validation, code completion, transformations, and generators.
A Command-Line Interface (CLI) makes contract validation and generators available outside any IDE.
Context Mapper can generate MDSL.
Work in progress: MDSL Web Application

See MDSL Tools page for more information.

More Information

MDSL Web Pages (this site)

Language reference and “getting started” resources:
- Primer, Tutorial, Quick Reference
- Endpoint Type, Data Types, Provider and Client, Technology Bindings
- Technology previews scenarios and stories, orchestration flows, AsyncMDSL,
Tools: Overview, CLI, update site for editor (Eclipse plugin)
- Service-oriented quick fixes and model transformations supporting “API First”
- Generators: OpenAPI generator, Protocol buffers generator, Graphql generator, Jolie generator, Java “Modulith” generator, Arbitrary textual generation with Freemarker
Language and tools repository (GitHub): XText grammar, examples folder

External links

Microservice API Patterns (MAP) and Interface Refactoring Catalog
An end-to-end service design demo is available on Medium also featuring Context Mapper, a DSL for strategic DDD and rapid OOAD (Context Mapper can generate MDSL). The demo takes you from a user story to a walking microservice skeleton (Spring Boot, Hipster, Heroku) in seven steps (partially automated in model transformations).
A microservices and DevOps conference report mentioning Context Mapper and MDSL.
Lakeside Mutual repository, featuring Domain-Driven Design (DDD) and microservices in an insurance company scenario (JavaScript frontends and Spring Boot backends)
Olaf Zimmermann’s Blog “The Concerned Architect”