Adding @id for external URIs

[stain]

Modifying 1.1-DRAFT spec to allow @id of Data Entity to be external/absolute URIs, and adds considerations before adding external URI to hasPart of an RO-Crate.

See #72 .

[proccaserra]

fixing the example for the Web-based Data Entities:

{ "@context": "https://w3id.org/ro/crate/1.1-DRAFT/context",
  "@graph":
  [
    {
        "@type": "CreativeWork",
        "@id": "ro-crate-metadata.jsonld",
        "conformsTo": {"@id": "https://w3id.org/ro/crate/1.1-DRAFT"},
        "about": {"@id": "./"}
  },  
  {
    "@id": "./",
    "@type": [
      "Dataset"
    ],
    "hasPart": [
      {
        "@id": "survey-responses-2019.csv"
      },
      {
        "@id": "https://zenodo.org/record/3541888/files/ro-crate-1.0.0.pdf"
      }
      ]
   },
  {
    "@id": "survey-responses-2019.csv",
    "@type": "File",
    "contentSize": "26452",
    "description": "Survey responses",
    "encodingFormat": "text/csv"
  },
  {
    "@id": "https://zenodo.org/record/3541888/files/ro-crate-1.0.0.pdf",
    "@type": "File",
    "contentSize": "310691",
    "description": "RO-Crate specification",
    "encodingFormat": "application/pdf"
  }
]
}

[fbacall]

When fetching a remote data entity, where should the local file be stored?

My assumption would be at the root of the crate, but what if it needs to go under data/input/foo/bar?

[stain]

@ptsefton you argued that remote files should be indicated as RepositoryObjects and not File?

Would you be able to sketch out how a modified example from digital-library-and-repository-content section would look?

@fbacall in #74 (comment) You seem to be walking into the world of BagIt fetch.txt - in which case I would expect the RO-Crate to refer to @id: data/bigfile.txt and fetch.txt say where data/bigfile.txt could be downloaded from to make the bag complete. In that scenario the Bag is a kind of transport mechanism of the RO-Crate.
See also #78 with @ThomasThelen

[ThomasThelen]

In regards to establishing a link between external and local data...

What about using schema:sameAs on the File object?

  {
    "@id": "survey-responses-2019.csv",
    "@type": "File",
    "contentSize": "26452",
    "description": "Survey responses",
    "encodingFormat": "text/csv",
    "sameAs": "https://zenodo.org/record/3541888/files/ro-crate-1.0.0.pdf"
  },
  {
    "@id": "https://zenodo.org/record/3541888/files/ro-crate-1.0.0.pdf",
    "@type": "File",
    "contentSize": "310691",
    "description": "RO-Crate specification",
    "encodingFormat": "application/pdf",
  }

This is likely something that @ieguinoa would run across with ResearchObject/ro-crate-py#2 while resolving remote data.