In August 2022, the United States Office of Science and Technology Policy (OSTP) issued a memo (PDF) on ensuring free, immediate, and equitable access to federally funded research (a.k.a. the “Nelson memo”). Crossref is particularly interested in and relevant for the areas of this guidance that cover metadata and persistent identifiers—and the infrastructure and services that make them useful.
Funding bodies worldwide are increasingly involved in research infrastructure for dissemination and discovery.
Preprints have become an important tool for rapidly communicating and iterating on research outputs. There is now a range of preprint servers, some subject-specific, some based on a particular geographical area, and others linked to publishers or individual journals in addition to generalist platforms. In 2016 the Crossref schema started to support preprints and since then the number of metadata records has grown to around 16,000 new preprint DOIs per month.
TL;DR One of the things that makes me glad to work at Crossref is the principles to which we hold ourselves, and the most public and measurable of those must be the Principles of Open Scholarly Infrastructure, or POSI, for short. These ambitions lay out how we want to operate - to be open in our governance, in our membership and also in our source code and data. And it’s that openness of source code that’s the reason for my post today - on 26th September 2022, our first collaboration with the JSON Forms open-source project was released into the wild.
Ans: metadata and services are all underpinned by POSI.
Leading into a blog post with a question always makes my brain jump ahead to answer that question with the simplest answer possible. I was a nightmare English Literature student. ‘Was Macbeth purely a villain?’ ‘No’. *leaves exam*
Just like not giving one-word answers to exam questions, playing our role in the integrity of the scholarly record and helping our members enhance theirs takes thought, explanation, transparency, and work.
Notification callback is a service you can use to notify you when a submission log is available for a metadata, batch query, or Cited-by query submission. Notification is provided in the form of a HTTP(S) URL where the log can be retrieved. If the notification callback service is enabled, you will no longer receive submission log emails.
How the notification callback service works
The callback will be an HTTP(S) request to a URL (notify-url) provided by the member with all data relayed via HTTPS headers. The notification specifies the availability of the result, some context of the request, and an HTTP(S) URL from which to get the result. The submission log may then be retrieved using the HTTP(S) URL.
The headers use the simple name and value structure; that is, the value has no additional structure that divides it into parts. To ensure that all Unicode values can be accommodated all header values will be UTF-8 encoded.
When the notify-url is used the following HTTPS headers are provided:
CROSSREF-NOTIFY-ENDPOINT: the notify-endpoint (required) is just the name used to identify the specific notification (more on this below)
CROSSREF-EXTERNAL-ID: the id given by the member with regards to the request. For metadata deposits, for example, it is the value of the doi_batch_id element (Optional)
CROSSREF-INTERNAL-ID: the id given by us with regards to the request (Optional)
CROSSREF-RETRIEVE-URL: the URL for the member to use to retrieve the request’s result. Since the HTTPS header value is UTF-8 encoded, the URL will contain no URI encodings. For example, an Á will not be encoded as %C3%81
CROSSREF-SERVICE-DATE: the date and time stamp of the service request. Learn more about format specification in RFC 2616.
CROSSREF-RETRIEVE-URL-EXPIRATION-DATE: the timestamp after which service result is no longer available at the given retrieve-url.
Setting up an endpoint
You’ll need to set up and register an endpoint to receive callbacks.
your endpoint info (notify-endpoint and notify-url) – the notify-endpoint is just a name to identify the specific notification. The notify-endpoint should be something you can recognize so when you receive responses that include the endpoint name, it is easy to know which of the callback feeds it is coming from. Thenotify-url has to be the actual URL of your callback receiver, as that is where the notification callback transmits to via http/https.
the services you’re activating the service for (metadata submissions, batch querying, Cited-by alerts)
the username and/or DOI prefix you’ll be using.
Make sure you inform us of any changes to your endpoint: if a message fails to send we will retry for up to a week after which you will no longer be able to receive it.
Example of a notification
For the submission 1368966558 the notification would be as follows (new lines have been added between header name and header value to improve readability):
The notification callback service can be queried for past callbacks. The query is implemented as an HTTPSservice.(Access control and limits to end-points and time frames TBD).
The query takes 3 criteria, the notify-endpoints, an inclusive from timestamp, and an exclusive until timestamp. All timestamps use the ISO 8061 format YYYY-MM-DD’T’hh:mm:ss’Z, for example, 2014-07-23T14:43:01Z.
The query results in a JSON array of callbacks. For example, querying for the single endpoint “1CFA094C-4876-497E-976B-6A6404652FC2” returns:
A flat structure is used to aid processing the result as a stream. There is no order defined.
The audit item is a record of attempted callbacks. It details the notify-endpoint’s notify-url used at the time of the callback, the timestamp of the callback, and the HTTPS status of the callback. If more than one attempt has been tried then the audit array will contain multiple elements; there is no order defined.
The usr and pwd are your Crossref username and password. The ENDPOINT value is a notify-endpoint or a space separated set of notify-endpoints.
Glossary of notification callback service terms
notify-url: the URL that the member provides and is used to notify them of the availability of a service request’s result. How the URL is provided to us will depend on the service.
notify-endpoint: an opaque token used to select a notify-url. The token will be anonymous and difficult to guess. The notify-endpoint is provided by the member. The notify-endpoint is associated with one notify-url (many notify-endpoints can be associated with the same notify-url).
retrieve-url: the URL that we provides that is used by the member to get the service request result.
notify-payload: the data that specifies what service request this notification is for. This payload will use HTTPS headers so as to be HTTPS method-neutral (such as POST, PUT).
retrieve-payload: the service result. Each service will define its own result content-type (that is very much like what would be sent in email today).
notification-authentication: This is the method of authentication we will use with the notify-url. Credentials are provided by the member.
retrieval-authentication: This is the method of authentication the member will use with the retrieve-url. The account credentials are provided by us.
Page owner: Isaac Farley | Last updated 2022-August-01