Layer 1 of MMS5 Flexo MMS handles the versioning of ‘models’ on an abstracted layer above the quadstore by emulating a git version control paradigm. Under the hood, Layer 1 must orchestrate the atomic insertion and deletion of triples to various named graphs on a single quadstore.
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A trivial solution for handling competing transactions is to allow the client to use preconditions when submitting SPARQL Updates with HTTP conditional requests. Essentially, an application can require that no other modifications have been made to some resource in order for their update to take effect. MMS5 Flexo MMS facilitates conditional requests using ETags that it generates based on the modifications made to database objects and model commits.
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PUT /orgs/openmbee/repos/demo/branches/develop <> mms:ref <./main> . |
MMS5 Flexo MMS will respond with something like:
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If some other client or application has modified the branch, MMS5 Flexo MMS will abort the update and respond with an HTTP 412 Precondition Failed code.
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