Declaring the root folder

Overview

Questions

• What is the root folder?

Objectives

• Create a top-level entity that can list the parts of the crate

RO-Crate Root

---

Next we’ll add another entity to the @graph array, to describe the RO-Crate Root:

JSON

{
    "@id": "./",
    "@type": "Dataset",
    "hasPart": [ 

    ]
}

Adding entities to the JSON array

Because we’re adding incrementally to the @graph array. It is important to remember the comma , between each entity, except for the final entity in the JSON array; and likewise for the properties within the JSON object for each entity. This is an artefact of the strict JSON file format rules to simplify parsing. The order of the entities within the @graph JSON-LD array and the order of the keys within a JSON object is not significant. The graph content is given by the @id cross-references.

You will add a comma here between the ro-crate-metadata.json entity, and the root data entity.

By convention, in RO-Crate the @id value of ./ means that this entity describes the folder in which the RO-Crate metadata file is located. This reference from ro-crate-metadata.json is therefore semantically marking the crate1 folder as being the RO-Crate Root.

RO-Crates can be published on the Web

This example is a folder-based RO-Crate stored on disk, and therefore absolute paths are avoided, e.g. in case the root folder is moved or archived as a ZIP file.

If the crate is being served from a Web service, such as a data repository or database where files are not organized in folders, then the @id might be an absolute URI instead of ./ – this is one reason why we point to the root entity from the metadata descriptor, see section Root Data Entity for details.

Key Points

• The RO-Crate Root is the top-level object of the RO-Crate
• The root identifier may be a URL, but commonly just ./ for the current folder