These questions are equivalent: - Can an integrity value be computed for each SPDXv3 Element? - Are SPDXv3 Elements immutable?
The RDF Concepts <https://www.w3.org/TR/rdf11-concepts/> document discusses mutability: ---------------------------------------------- *1.5 RDF and Change over Time* 1. The RDF data model is atemporal: RDF graphs are static snapshots of information. 2. However, RDF graphs can express information about events and about temporal aspects of other entities, given appropriate vocabulary terms. 3. Since RDF graphs are defined as mathematical sets, adding or removing triples from an RDF graph yields a different RDF graph. 4. We informally use the term RDF source to refer to a persistent yet mutable source or container of RDF graphs. An RDF source is a resource that may be said to have a state that can change over time. A snapshot of the state can be expressed as an RDF graph. For example, any web document that has an RDF-bearing representation may be considered an RDF source. Like all resources, RDF sources may be named with IRIs and therefore described in other RDF graphs. Intuitively speaking, changes in the universe of discourse can be reflected in the following ways: a. An IRI, once minted, should never change its intended referent. (See URI persistence [WEBARCH].) b. Literals, by design, are constants and never change their value. c. A relationship that holds between two resources at one time may not hold at another time. d. RDF sources may change their state over time. That is, they may provide different RDF graphs at different times. e. Some RDF sources may, however, be immutable snapshots of another RDF source, archiving its state at some point in time. ---------------------------------------------- SPDXv3 Elements form a graph where each node is an Element identified by its "id" IRI. The Element graph [statement 1] is distinct from Artifacts - the ArtifactURL property of an Artifact Element may, for example, reference a specific version (immutable) or the latest version (mutable) of an entity [statement 2]. It seems obvious to me that statement 1. (every RDF graph is a static snapshot) and bullet a. (an IRI assigned to an Element always refers to the same Element) require that the Element (all of its properties including its "id" IRI) are immutable. The lifecycle of RDF graphs is addressed by statements 3 and 4: If a graph is created from Elements 1, 2, 3, 4, and 5, then it is fixed forever. If Element 6 is then created, referencing previous Elements, it yields a different RDF graph since it adds an Element to the previous graph. None of Elements 1-5 reference Element 6 in either graph. Do we agree? Dave -=-=-=-=-=-=-=-=-=-=-=- Links: You receive all messages sent to this group. View/Reply Online (#4219): https://lists.spdx.org/g/Spdx-tech/message/4219 Mute This Topic: https://lists.spdx.org/mt/86264868/21656 Group Owner: [email protected] Unsubscribe: https://lists.spdx.org/g/Spdx-tech/unsub [[email protected]] -=-=-=-=-=-=-=-=-=-=-=-
