2. PIDINST handles at ePIC

Properties, sub-properties and attributes of the PIDINST metadata schema used in ePIC PID handle records can be viewed as follows. Use ‘#’ before ‘objects’ to interchange between human-readable and JSON representations. Each property, sub-property and attribute is resolvable through a unique handle record:

Human-readable http://dtr-test.pidconsortium.eu/#objects/21.T11148/17ce618137e697852ea6
JSON representation http://dtr-test.pidconsortium.eu/objects/21.T11148/17ce618137e697852ea6

2.1. Generating a new instrument PID

ePIC handles are accessed and managed via a RESTful web service, using the HTTP application protocol. This service or Application Programming Interface (API) uses JSON as the primary exchange format. Available are the generic and more basic Handle API or, if implemented at the PID service used, the ePIC API that comes with its own business logic and additional services. In our following examples PIDINST handles are created via the ePIC API in the ePIC API test environment with a view to moving the architecture to the production environment in the future. There is also an overview for the basic CRUD operations on PIDs for either the ePIC API or the Handle API at the end.

In order to generate new PIDs and assign them to your instruments, it is necessary to become an ePIC member (provider), or work with one of their current members or repositories that has their own ePIC API endpoint. To create a PID using the test environment you will need to obtain credentials (username and password) for authentication using the test environment prefix 21.T11998. These can be obtained from ePIC by emailing support@pidconsortium.net.

PIDs are typically created using POST/PUT methods. Using the POST method will automatically generate a Universally Unique Identifier (UUID) within the suffix of a handle record. Alternatively a suffix can be manually created via PUT method using a local identifier (see https://doc.pidconsortium.eu/guides/api-create/).

All examples below use cURL requests at the command line (in Linux). Requests can also use PHP, Perl and Python (see https://doc.pidconsortium.eu/guides/api-create/). Examples also use the test API endpoint http://vm04.pid.gwdg.de:8081/handles/. Each ePIC member may use their own API end-point.

To generate a PID handle record automatically generating a UUID for the suffix:

curl -v -u "username:password" -H "Accept:application/json" -H "Content-Type:application/json" -X POST --data '[{"type":"URL","parsed_data":"https://linkedsystems.uk/system/instance/TOOL0022_2490/current/"}]' http://vm04.pid.gwdg.de:8081/handles/21.T11998/

Result: https://vm04.pid.gwdg.de:8081/handles/21.T11998/0000-001A-64A4-A

To generate a PID handle record automatically generating a UUID within the suffix:

curl -v -u "username:password" -H "Accept:application/json" -H "Content-Type:application/json" -X POST --data '[{"type":"URL","parsed_data":"https://linkedsystems.uk/system/instance/TOOL0022_2490/current/"}]' http://vm04.pid.gwdg.de:8081/handles/21.T11998/\?prefix=BODC\&suffix=TEST

Result: https://vm04.pid.gwdg.de:8081/handles/21.T11998/BODC-0000-001A-64A3-B-TEST

To manually generate a suffix using PUT method:

curl -v -u "username:password" -H "Accept:application/json" -H "Content-Type:application/json" -X PUT --data '[{"type":"URL","parsed_data":"https://linkedsystems.uk/system/instance/TOOL0022_2490/current/"}]' http://vm04.pid.gwdg.de:8081/handles/21.T11998/564987-8865544-9998

Result: https://vm04.pid.gwdg.de:8081/handles/21.T11998/564987-8865544-9998

2.2. Viewing PID handle records

If you have specified the URL property in the handle record it will automatically redirect you to it when you view the handle record:


If you want to see the handle record then use:


The REST API calls can also yield JSON responses:


2.3. Updating the description of a PID handle record

Properties are updated using the PUT method by either specifying the JSON properties directly in the cURL request or parsing them via a JSON file (see JSON example).

Directly specifying properties within the cURL request:

curl -v -u "username:password" -H "Accept:application/json" -H "Content-Type:application/json" -X PUT --data '[{"type": "21.T11148/8eb858ee0b12e8e463a5","parsed_data": "{\"identifierValue\":\"http://hdl.handle.net/21.T11998/BODC-0000-001A-64A3-B-TEST\",\"identiferType\":\"MeasuringInstrument\"}"},{"type": "21.T11148/4eaec4bc0f1df68ab2a7","parsed_data": "[{\"Owner\": {\"ownerName\":\"National Oceanography Centre\",\"ownerContact\":\"louise.darroch@bodc.ac.uk\",\"ownerIdentifier\":{\"ownerIdentifierValue\":\"http://vocab.nerc.ac.uk/collection/B75/current/ORG00009/\",\"ownerIdentifierType\":\"URL\"}}}]"}]' http://vm04.pid.gwdg.de:8081/handles/21.T11998/BODC-0000-001A-64A3-B-TEST

Note: Double quotes must be escaped with a backslash (\) within the JSON parsed_data string

Specifying properties with a JSON file:

curl -v -u "username:password" -H "Accept:application/json" -H "Content-Type:application/json" -X PUT --data @/users/.../ePIC_json_example.json http://vm04.pid.gwdg.de:8081/handles/21.T11998/BODC-0000-001A-64A3-B-TEST

2.4. Managing PIDs

2.4.1. Using the ePIC API

The following HTTP protocol methods enable users to manage their PID handle records using the ePIC API based on username-password. Server: vm04.pid.gwdg.de, Port: 8081, Resources: handles/

Get a PID:

curl -D- -u "username:password" -X GET -H "Content-Type: application/json" http://vm04.pid.gwdg.de:8081/handles/21.T11998/BODC-0000-001A-64A3-B-TEST

Delete a PID (not allowed for production Handles):

curl -v -u "username:password" -H "Accept:application/json" -H "Content-Type:application/json" -X DELETE http://vm04.pid.gwdg.de:8081/handles/21.T11998/BODC-0000-001A-64A3-B-TEST

Update a PID:

curl -v -u "username:password" -H "Accept:application/json" -H "Content-Type:application/json" -X PUT --data '[{"type":"21.T11148/8eb858ee0b12e8e463a5","parsed_data":"{\"identifierValue\":\"http://hdl.handle.net/21.T11998/BODC-0000-001A-64A3-B-TEST\",\"identiferType\":\"MeasuringInstrument\"}"}]' http://vm04.pid.gwdg.de:8081/handles/21.T11998/BODC-0000-001A-64A3-B-TEST

2.4.2. Using the Handle API

The following HTTP protocol methods enable users to manage their PID handle records using the generic Handle API based on Certificates. Server: vm04.pid.gwdg.de, Port: 8081, Resources: handles/

The process to derive the privkey.pem and certificate_only.pem from a is described for instance at: http://eudat-b2safe.github.io/B2HANDLE/creatingclientcertificates.html

The Handle API does not have an internal suffix generator. The suffix needs to be provided by the user.

The Handle API only knows POST, GET and DELETE methods, which means that, if the Credentials are sufficient, an existing PID could be accidentally overwritten by a request intended for creation. This has to be detected by the user in advance.

Access parameters:

For given username, index, where the public key HS_PUBKEY is stored, and prefix the certificate files are stored here with the naming convention ${INDEX}_${PREFIX}_${USER}_???.pem.

PREFIX="21.T11998" # prefix of the PID service
USER="USER21" # USER that has access to PIDs under $PREFIX
INDEX="300"  # index where HS_PUBKEY is stored for $USER
SERVPORT="vm04.pid.gwdg.de:8001" # PID service and port
VERBOSE="" # optional “ -v "
# Certificates

Create Handle:

curl -s --insecure ${VERBOSE} --key ${USERKEY} --cert ${USERCERT} -H "Content-Type:application/json" -H 'Authorization: Handle clientCert="true"' -X PUT --data  '{"values":[{"index":100,"type":"HS_ADMIN","data":{"value":{"index":'${INDEX}',"handle":"'${PREFIX}'\/'${USER}'","permissions":"011111110011","format":"admin"},"format":"admin"}},{"index":1,"type":"URL","data":"www.gwdg.de"}]}' https://${SERVPORT}/api/handles/${PREFIX}/test_epic3_1234

Get Handle created:

curl -s --insecure ${VERBOSE} --key ${USERKEY} --cert ${USERCERT} -H "Content-Type:application/json" -H 'Authorization: Handle clientCert="true"' -q https://${SERVPORT}/api/handles/test_epic3_1234

Modify Handle created:

curl -s --insecure ${VERBOSE} --key ${USERKEY} --cert ${USERCERT} -H "Content-Type:application/json" -H 'Authorization: Handle clientCert="true"' -X PUT --data  '{"values":[{"index":100,"type":"HS_ADMIN","data":{"value":{"index":'${INDEX}',"handle":"'${PREFIX}'\/'${USER}'","permissions":"011111110011","format":"admin"},"format":"admin"}},{"index":1,"type":"URL","data":"pid.gwdg.de"}]}' https://${SERVPORT}/api/handles/${PREFIX}/test_epic3_1234

Delete Handle created:

curl -s --insecure ${VERBOSE} --key ${USERKEY} --cert ${USERCERT} -H "Content-Type:application/json" -H 'Authorization: Handle clientCert="true"' -X DELETE  https://${SERVPORT}/api/handles/test_epic3_1234