• Last Published: 2018-06-18
• |
• Version: 3.3.0

KiWi Versioning

The KiWi Versioning module allows logging of updates to the triple store as well as accessing snapshots of the triple store at any given time in history. In many ways, it is similar to the history functionality offered by Wiki systems. KiWi Versioning can be useful for many purposes:

• for tracking changes to resources and the whole repository and identifying the source (provenance) of certain triples
• for creating snapshots of the repository that are “known to be good” and referring to these snapshots later while still updating the repository with new data
• for more easily reverting errorneous changes to the triple store, in a similar way to a wiki; this can e.g. be used in a “data wiki”

Currently, the KiWi Versioning module allows tracking changes and creating snapshots. Reverting changes has not yet been implemented and will be added later (together with support for pruning old versions).

Versioning is tightly bound to the transaction support: a version is more or less the transaction data after commit time. This corresponds to the concept of “unit of work”: a unit of work is finished when the user explicitly commits the transaction (e.g. when the entity has been completely added with all its triples or the ontology has been completely imported).

 <dependency>
     <groupId>org.apache.marmotta</groupId>
     <artifactId>kiwi-versioning</artifactId>
     <version>3.3.0</version>
 </dependency>

KiWiStore store = new KiWiStore("test",jdbcUrl,jdbcUser,jdbcPass,dialect, "http://localhost/context/default", "http://localhost/context/inferred");
KiWiTransactionalSail tsail = new KiWiTransactionalSail(store);
KiWiVersioningSail vsail = new KiWiVersioningSail(tsail);
repository = new SailRepository(vsail);
repository.initialize();

// do something with the repository (e.g. add data)
...

// list all versions (note that there are many methods with different parameters, including a subject resource,
// a date range, or both)
RepositoryResult<Version> versions = vsail.listVersions();
try {
    while(versions.hasNext()) {
        Version v = version.next();

        // do something with v
    }
} finally {
    versions.close();
}

// get a snapshot connection for a certain date
Date snapshotDate = new Date(...);
RepositoryConnection snapshotConnection = vsail.getSnapshot(snapshotDate);
try {
    // access the triples in the snapshot as they were at the time of the snapshot
    ...
} finally {
    snapshotConnection.close();
}