🔗 The language of the boundary

The article discusses the development journey of creating a JSON Schema validator library for Elixir, detailing the complexities encountered when integrating JSON schema validation with Open API Spex. It emphasizes the necessity of validating data at boundaries, where untrusted external data is handled. The author, reflecting on past experiences, distinguishes between validating solely within Elixir and creating a shared understanding through JSON Schema among various programming teams, particularly in relation to Python and TypeScript. In exploring the challenges of maintaining and implementing validation rules effectively, the piece advocates for treating validation rules as data rather than as code, highlighting the importance of schemas as a means of ensuring compatibility and accuracy across different technologies. Ultimately, the author champions JSON Schema as the preferred solution for establishing clear, functional boundaries in application development.