Solid IoT (LwM2M) Data saver (soliddatasaver)

Description

This Node.js program allows us to save data from a Leshan server into a users Solid datapod (if their credentials are available), without having to interface with a GUI.

source files

Found in src/

• main.mjs: Starts the program. First logs in to the Solid pod(s) and dowloads the ontology, then registers itself at the leshan server(s).
• leshanEventRetriever.mjs: Registers EventListener with a callback
• rmlmapper.mjs: Maps incoming JSON object to RDF(N3). Does some preprocessing and uses then RocketRML.
• solidPodSaver.mjs: Logs in into Solid pod(s) and accepts RDF measurements, which are send to the Solid pod.
• getPodData.mjs: Return the right IoTDocument to write our data to, if webID is given. Uses the private type index of solid.
• ontologySearcher.mjs: Downloads LwM2M ontology and uses this to query which Object/Resource Class is bound to which number. Thus, this is used to map objectnumber <-> objectname (like: object3303 <-> lwm2m:LWM2MTemperatureObject).

In config/

• config.mjs: All configuration parameters can be adjusted here.
• mapping_uuid.ttl: RML file to denote how the transformation from JSON to RDF has to happen. This file uses skolemization of blank nodes, which means that blank nodes get a random IRI.
• mapping_blank_nodes.ttl: Same as above, but using blank nodes instead of nodes with a random IRI. This would be preferred, but 'rdflib.js' has some problems with blank nodes, thinking they are the same when they shouldn't be. (Thus squashing measurement into 1 node :/)

Installation and usage

Generator tool

1. Go into scripts/generator.py and edit the program parameters to your liking.
2. run py generator.py or python3 generator.py to generate the static data.

Datasaver

1. After cloning repository, run npm install to install all needed dependencies into the node_modules folder.
2. !!! Important: Due to some ridiculous unpatched issue, for this to work following patch needs to be applied manually:
   • Go to node_modules/@solid/cli/source/SolidClient.js at line 110.
   • Add scope: ['openid'] to the authenticate object just like here.
3. When fix is applied, use npm start to run the datasaver program.

Bugs

seems like there can occur a race condition (in the start of the program), causing this:

genid:8a545544-6ee9-46aa-a3f1-2a48df36b9e5
    a om:MinMeasuredValue, om:ResourceInstance;
    om:hasTimeStamp
        "2020-04-30T15:33:12.313Z"^^XML:dateTime,
        "2020-04-30T15:33:12.569Z"^^XML:dateTime;
    om:hasValue "-544.6"^^XML:float;
    om:organizedInto n0:0.