Going Beyond JSON: Representers, ASTs, and Code

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Hi, I'm Stephen. I've thought way too much about JSON @Stephen_Mizell

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JSON { "name": "John Doe" }

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JSONx John Doe

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Ruby { :name => "John Doe" } Or... json.name "John Doe"

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Refract { "element": "object", "content": [ { "element": "member", "content": { "key": { "element": "string", "content": "name" }, "value": { "element": "string", "content": "John Doe" } } } ] }

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These are all instruc.ons to build some internal structure of data.

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Abstract Source Tree A tree representa*on of the abstract syntac*c structure of source code wri5en in a programming language.

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Homoiconicity The code and representa.on of the code (AST) is the essen.ally the same

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Syntax + Structure + Seman.cs + Data Find ways to modularize and compose

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Instead of JSON -> Applica6on Logic Use JSON -> AST -> Applica2on Logic

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Treat your formats—JSON and others—as languages. Treat them as DSLs. Parse them to canonical structures decoupled from the format itself.

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Quick Demo

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Representers

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Coupling to HAL { "_links": { "item": { "href": "..." } } } // Get the item link doc._links.item.href

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Coupling to HAL { "_links": { "item": [ { "href": "..." }, { "href": "..." } ] } } // Broken! doc._links.item.href

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Using a Representer doc.links.hasRel('item'); doc.links.getByRel('item').first(); Decoupled from structure, syntax, and format.

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Using a Representer doc.links.add('item', 'http://example.com/1'); doc.links.add('item', 'http://example.com/2'); Decoupled from hypermedia formats. Easy to test what your model is independent of formats.

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Connascence of Type (CoT)

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Instead of JSON -> Applica6on Logic Use JSON -> Representer -> Applica5on Logic

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This provides a clearer boundary between your applica5on and the outside world

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Your data model is not your object model is not your resource model is not your message model. — Mike Amundsen

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Real world example GraphQL has an AST. OpenAPI does not.

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Takeaways • Deﬁne boundaries • We shouldn't have breaking changes—clients should just degrade • Consider inputs/outputs as languages • Think about canonical structures for crea?ng unity in a world of diversity