GeoJSON is not hypermedia

2008-11-13T23:36:17Z in web, data, rest

The GeoJSON working group chose to omit links from the specification (outside of coordinate reference systems). In conclusion, GeoJSON 1.0 is not a hypermedia format. Without links there are no levers of application state to be seized, no hypertext constraint, and therefore no REST.

Consider, as an example of a hypermedia format, Atom and extensions in AtomPub: "alternate", "related", "self", and "edit" links are designed to satisfy REST's hypertext constraint and permit hypertext to be used as the engine of application state. Without links of the edit kind (especially), HTTP Geo-CRUD protocols using GeoJSON couple clients and servers together, an undesirable property in a system like the Web. This is not to say that coupling is going to kill your applications, just that the components don't have much freedom to evolve (think migrate or upgrade) separately.

Are there any good linking options for JSON? Subbu Allamaraju explores that question here and here and floats an object not unlike the only link example in GeoJSON. Both are inspired by atom:link and HTML's link.

Should GeoJSON become a hypermedia format? I don't know the answer to that, but I think it's more likely that GeoJSON geometry (and maybe feature) objects will find their way into other yet-to-emerge JSON-based media types.

Comments

1Re: GeoJSON is not hypermedia

Guillaume, 2008-11-14T08:58:18Z

I've never thought GeoJSON as an hypermedia format. IMHO, it's an interchange format, like old MIF/MID, designed for web apps, and describing geo features, easy to generate from server side, easy to read on client side. If hypermedia is needed somewhere, couldn't geoJSON be embedded in a atompub stream ? Or couldn't the atompub contains a link towards a geoJSON ressource ?

2Re: GeoJSON is not hypermedia

Subbu Allamaraju, 2008-11-14T15:55:00Z

@Guillaume: IMO, the question isn't whether a format like GeoJSON is a hypermedia format or not. To improve loose-coupling and discoverability of the contract, it is necessary to explore ways to enhance representations with runtime linking, and by adding links to JSON, you can make it a hypermedia format. Similarly, one might see PDF as a binary format, but it is actually a format that allows hyperlinking, and hence is a hypermedia format.

3Re: GeoJSON is not hypermedia

Sean, 2008-11-14T19:34:09Z

Thanks for the comment, Subbu. Guillaume, I'm seeing references to "RESTful" APIs using GeoJSON (I'd rather not single any one out) and felt it worth pointing out that such a thing is technically not possible, and specifically what GeoJSON lacks.

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