Fedora provides factilities by which to conduct multiple operations against a repository in an atomic fashion. This is accomplished by the use of headers on requests. An atomic series of operations should not require any more requests than the same series of operations performed non-atomically.
A client begins an atomic series of requests by sending any request to any resource with
the header Atomic-Start. The server MUST respond by including a header
Atomic-ID with a unique identifier for the series. The effect of the
request, if it has one, and if the request is successful, MUST be visible to clients
using that identifier to add to this series of requests, as described
below, until the series expires or is finished. The effect of the
request, if it has one, and if the request is successful, SHOULD NOT be visible to
clients not using that identifier to add to this series of requests. The effect of the
request MUST NOT be durable unless and until the series is successfully
finished.
A client adds to an atomic series of requests by sending any request to any resource with
the header Atomic-ID and the identifier for that series. The effect of the
request, if it has one, and if the request is successful, MUST be visible to clients
using that identifier to add to this series of requests, until the series expires or is
finished. The effect of the request, if it has one, and if the request is successful,
SHOULD NOT be visible to clients not using that identifier to add to this series of
requests. The effect of the request MUST NOT be durable unless and until the series is
successfully finished. An implementation MUST respond
to any request with multiple Atomic-ID headers with different values or
with an Atomic-ID header with a value that has not been assigned to a
series or that has expired (see below) with a 409 response.
That response MUST include an Atomic-Invalid header or headers with the
invalid identifier or identifiers.
An implementation MAY enforce automatic expiration for an atomic series of requests.
If so, the response to any request made as part of the series MUST have a
Atomic-Expires header with the HTTP datetime at which the series will
expire. An implementation MAY extend the lifetime of a series upon the receipt of any
request specifying the unique identifier of that series in the Atomic-ID
header.
A client can finish an atomic series of requests by sending any
PUT/POST/PATCH/DELETE request
including both a Atomic-Commit header and a Atomic-ID
header with the unique identifier of an existing series. The effects of all requests
in the series MUST become durable and MUST become visible to all clients. The unique
identifier of the series MUST be expired and MUST NOT be reused.
A client can finish an atomic series of requests by sending any request including
both a Atomic-Abort header and a Atomic-ID header with
the unique identifier of an existing series. The effects of all requests in the
series MUST disappear to all clients, and MUST be durably gone. The unique identifier
of the series MUST be expired and MUST NOT be reused.