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@thi.ng/rstream-query

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Readme

@thi.ng/rstream-query

This project is part of the @thi.ng/umbrella monorepo.

About

@thi.ng/rstream based triple store & reactive query engine with high re-use ratio of sub-query results. Inserted triples / facts are broadcast to multiple indexing streams and any query subscriptions attached to them. This enables push-based, auto-updating query results, which are changing each time upstream transformations & filters have been triggered (due to updates to the set of triples / facts).

Triples are 3-tuples of [subject, predicate, object]. Unlike with traditional RDF triple stores, any JS data types can be used as subject, predicate or object (though support for such must be explicitly enabled & this feature is currently WIP).

Current features

Entirely based on stream abstractions provided by @thi.ng/rstream
All data transformations done using @thi.ng/tranducers
Dynamic dataflow graph construction via high-level methods
Extensive re-use of existing sub-query results (via subscriptions)
Auto-updating query results

Status

This project is currently still in early development and intended as a continuation of the Clojure based thi.ng/fabric, this time built on the streaming primitives provided by @thi.ng/rstream.

Installation

yarn add @thi.ng/rstream-query

Usage examples

import { TripleStore } from "@thi.ng/rstream-query";

store = new TripleStore();
store.addTriples([
    ["london", "type", "city"],
    ["london", "part-of", "uk"],
    ["portland", "type", "city"],
    ["portland", "part-of", "oregon"],
    ["portland", "part-of", "usa"],
    ["oregon", "type", "state"],
    ["usa", "type", "country"],
    ["uk", "type", "country"],
]);

// find all subjects with type = country
store.addParamQuery("countries", ["?country", "type", "country"]).subscribe(trace("country results:"));

// find all relations for subject "london"
store.addParamQuery("london", ["london", "?p", "?o"]).subscribe(trace("london results:"));

// country results: [ { country: 'usa' }, { country: 'uk' } ]
// london results: [ { p: 'type', o: 'city' }, { p: 'part-of', o: 'uk' } ]

After setting up the above 2 queries, the dataflow topology then looks as follows:

graphviz output

The blue nodes are TripleStore-internal index stream sources, which emit changes when new triples are added. The red nodes are basic pattern queries, responsible for joining the individual (S)ubject, (P)redicate and (O)bject sub-queries. The results of these are then further transformed to bind result values to query variables, as well as the final subscriptions to output them to the console (using trace, see above).

Btw. The diagram has been generated using @thi.ng/rstream-dot and can be recreated by calling store.toDot() (for the above example)

(Many) more features forthcoming...

Authors

Karsten Schmidt