metadata-schemas

PASS metadata schemas

This repository contains JSON schemas and example data intended to describe PASS submission metadata as per the schemas for forms and validation design, as well as a schema service that will retrieve, dereference, and place in the correct order all schemas relevant to a given set of pass Repositories.

Schemas

The JSON schemas herein describe the JSON metadata payload of PASS submission entities. They serve two purposes 1. Validation of submission metadata 2. Generation of forms in the PASS user interface

These schemas follow a defined structure where properties in /definitions/form/properties are intended to be displayed by a UI, e.g.

{
    "title": "Example schema",
    "description": "NIHMS-specific metadata requirements",
    "$id": "https://github.com/OA-PASS/metadata-schemas/jhu/example.json",
    "$schema": "http://json-schema.org/draft-07/schema#",
    "type": "object",
    "definitions": {
        "form": {
            "title": "Please provide the following information",
            "type": "object",
            "properties": {
                "journal": {
                    "$ref": "global.json#/properties/journal"
                },
                "ISSN": {
                    "$ref": "global.json#/properties/ISSN"
                }
            }
        },
    },
    "allOf": [
        {
            "$ref": "global.json#"
        },
        {
            "$ref": "#/definitions/form"
        }
    ]
}

A pass repository entity represents a target repository where submissions may be submitted. Each repository may link to one or more JSON schemas that define the repository's metadata requirements. In terms of expressing a desired user interface experience, one may observe a general pattern of pointing to a "common" schema containing ubiquitous fields, and additionally pointing to a "repository-specific" schema containing any additional fields that are unique to a given repository.

As a concrete example, the NIHMS repository may point to the common.json schema, as well as the nihms.json schema.

Schema service

The schema service is an http service that accepts a list of PASS repository entity URIs as application/json or newline delimited text/plain, in a POST request. for example:

[
    "http://pass.jhu.edu/fcrepo/rest/repositories/foo",
    "http://pass.jhu.edu/fcrepo/rest/repositories/bar",
]

For each repository, the schema service will retrieve the list of schemas relevant to the repository, place that list in the correct order (so that schemas that provide the most dependencies are displayed first), and resolves all $ref references that might appear in the schema.

If a merge query parameter is provided (with any value, e.g. ?merge=true), then all schemas will be merged into a single union schema. If the service is unable to merge schemas together, it will respond with 409 Conflict status. In this case, a client can issue a request without the merge query parameter to get the un-merged list of schemas.

The result is an application/json response that contains a JSON list of schemas.

building

Building the schema service requires go 1.11 or later.

The schema service may be built by running:

go build ./cmd/pass-schema-service

.. which will create an executable in the current directory. go install ./cmd/schemas may be used instead, which will install the binary to your ${GOPATH/bin}. If you have that in your $PATH, this is particularly convenient for building and running cli commands.

running

To get a list of command line options, do

pass-schema-service help serve

To run the schema service,

pass-schema-service serve /path/to/schemas

where /path/to/schemas is a directory, or files(s) containing JSON schemas. This statically loads the set of schemas this service may return. For example:

$ ./pass-schema-service serve jhu/
2019/02/21 16:40:40 Loaded schema https://github.com/OA-PASS/metadata-schemas/jhu/common.json
2019/02/21 16:40:40 Loaded schema https://github.com/OA-PASS/metadata-schemas/jhu/global.json
2019/02/21 16:40:40 Loaded schema https://github.com/OA-PASS/metadata-schemas/jhu/jscholarship.json
2019/02/21 16:40:40 Loaded schema https://github.com/OA-PASS/metadata-schemas/jhu/nihms.json
2019/02/21 16:40:40 Listening on port 59152

This output shows the random port the server is listening on, and lists the schemas it loaded.

configuration/options

The help page describes the possible commandline options. Each option has a corresponding environment variable that may be used instead:

$ ./pass-schema-service help serve
NAME:
    pass-schema-service serve - Sereve the PASS schema service over http

USAGE:
    pass-schema-service serve [command options] [ file | dir ] ...

DESCRIPTION:


    An optional list of files or directories may be provided, which will be
    examined for the presence of schema files which will be used for static lookups


OPTIONS:
    --external value, -e value  External (public) PASS baseuri [$PASS_EXTERNAL_FEDORA_BASEURL]
    --internal value, -i value  Internal (private) PASS baseuri [$PASS_FEDORA_BASEURL]
    --username value, -u value  Username for basic auth to Fedora [$PASS_FEDORA_USER]
    --password value, -p value  Password for basic auth to Fedora [$PASS_FEDORA_PASSWORD]
    --port value                Port for the schema service http endpoint (default: 0) [$SCHEMA_SERVICE_PORT]
    --merge, -m                 Always merge result schemas into a single one [$SCHEMA_SERVICE_MERGE]

Command line options have a short form (-i) or a long form (--internal), which may be user interchangably. For example, the following will run the schema service on port 8080, and user the username myUser and passeord foo for retrieving repository entities from the Fedora

env SCHEMA_SERVICE_PORT=8080 pass-schema-service serve -u myUser --password foo  /path/to/schemas

Updating and deploying live schemas

All schemas in the schemas directory are served by github pages. When a schema changes, it needs to be deployed to the gh-pages branch to be served by http:

git subtree push --prefix schemas origin gh-pages

In addition, the go library exports the schemas and makes them statically available for validation. To bake new schemas into the code, do:

go generate ./...

Tests will fail if schemas are changed, but this step is not run