Describo

Identifiers in your crate ​

According to the JSON-LD spec, IRI's should be used to identify nodes. That said, the spec defines some other types of identifiers that are valid in JSON-LD but are not valid IRI's.

The RO Crate specification goes further in this regard.

For the sake of validation, this component conforms to both but the SHOULD's in the RO Crate spec are treated as MUST's.

What is valid ​

Here's the validateId function with comments explaining what the check is

JS
export function validateId({ id, type }) {
    if (!id) {
        return { isValid: false };
    }

    // if it's the root descriptor - it's valid
    if (id === "ro-crate-metadata.json") {
        return { isValid: true };
    }

    if (type) {
        // if type matches File or Dataset then whatever is provided is valid
        type = isArray(type) ? type.join(", ") : type;
        if (type.match(/file/i)) return { isValid: true };
        if (type.match(/Dataset/i)) return { isValid: true };
    }

    // if there are spaces in the id - encode them
    if (id.match(/\s+/)) {
        id = id.replace(/\s+/g, "%20");
    }

    // @id is relative
    if (id.match(/^\/.*/)) return { isValid: true };

    // @id starting with . is valid
    if (id.match(/^\..*/)) return { isValid: true };

    // @id starting with # is valid
    if (id.match(/^\#.*/)) return { isValid: true };

    // @id with blank node is valid
    if (id.match(/^\_:.*/)) return { isValid: true };

    // arcp URI's are valid
    if (id.match(/arcp:\/\/name,.*/)) return { isValid: true };
    if (id.match(/arcp:\/\/uuid,.*/)) return { isValid: true };
    if (id.match(/arcp:\/\/ni,sha-256;,.*/)) return { isValid: true };
    // return { isValid: true };

    // otherwise check that the id is a valid IRI
    try {
        let result = validateIriPkg.validateIri(id, validateIriPkg.IriValidationStrategy.Strict);
        if (!result) {
            // it's valid
            return { isValid: true };
        } else if (result?.message?.match(/Invalid IRI according to RFC 3987:/)) {
            // otherwise
            const message = `${result.message.replace(
                /Invalid IRI according to RFC 3987:/,
                "Invalid identifier"
            )}. See https://github.com/describo/crate-builder-component/blob/master/README.identifiers.md for more information.`;
            return { isValid: false, message };
        }
    } catch (error) {
        return { isValid: false };
    }
}

What happens when crates are loaded into the component ​

Every node is checked for a valid id and if they all are, then the crate is loaded.

As the component is ingesting each of the entities, it checks that it has an @type property and tries to set it accordingly. To do this it uses the @id of the entity and if it's a URL, then @type becomes URL otherwise @type is set to Thing.