Hosting and serving of EPCIS and CBV contexts

[VladimirAlexiev]

@mgh128 @CraigRe @jmcanterafonseca-iota

236 discusses whether the context link should be hard-coded in JSON and/or supplied externally.

This issue discusses where the context should be stored and how it should be served. Please use the numbering below when replying (or add a new item). Use eg 3) so markdown doesn't change your number.

1) currently it's in Github Pages: https://gs1.github.io/EPCIS/epcis-context.jsonld. 2) the spec line 2289 specifies a different URL: https://ns.gs1.org/ref/EPCIS-context, so ALL EXAMPLES MUST BE FIXED before release 3) It's a big problem for my automated processing (JSONLD->Turtle->Diagrams) that the context is not updated frequently enough. I suspect it will be even harder to update when it lands in its official location :-( 4) @CraigRe wrote "!!! Need to verify this link and CORS-compliant hosting before ratification" 5) Apparently, hosting a context for a big user population is far from trivial, despite JSONLD tools often including context caching. @danbri, can you say more from your schema.org experience? 5) The context MUST be returned as content type application/ld+json 6) I don't know if there's a standard where to put the context. Let's examine a couple of ontologies:

• schema.org returns it at the semantic namespace URL. On the other hand, it doesn't return the whole ontology there, which imho is not so good:

  curl -LI -Happlication/ld+json http://schema.org
  HTTP/1.1 301 Moved Permanently
  Location: https://schema.org/
  HTTP/2 200
  link: </docs/jsonldcontext.jsonld>; rel="alternate"; type="application/ld+json"

• GS1 voc doesn't return either the context nor the ontology as pure JSONLD. Instead, both https://www.gs1.org/voc/ and https://www.gs1.org/voc/AdditionalProductClassificationDetails, with any content type, return HTML the whole ontology as embedded JSONLD script. I don't see how to get the context ONLY.

  curl -LI -Happlication/ld+json https://www.gs1.org/voc/
  HTTP/1.1 200 OK
  Content-Type: text/html; charset=UTF-8

• I would recommend to put it at https://ns.gs1.org/epcis/context.jsonld, whereas https://ns.gs1.org/epcis/ (with or without trailing slash) should return the ontology, with content negotiation. 8) cbv: is not defined in the EPCIS context, so we either need to define it, or repeat 1-7 for a separate CBV context. (Whatever we decide about EPCIS context, we should do the same for a separate CBV context.)

[VladimirAlexiev]

This is related to #228 but different

[VladimirAlexiev]

8: we tend to think describing CBV in the EPCIS context is better, so as not to force people to always use an array, and to support the case "pure JSON -> external context with HTTP Link -> JSONLD" (see #236)

[VladimirAlexiev]

1 & 2 the final location will probably be https://ns.gs1.org/ref/epcis-context (with optional extension .jsonld), cannot be at github.