![Mapping service interfaces to Node-red
To allow OSGi components to appear as Node-red nodes, they need to
implement a suitable lifecycle service interface - NodeComponent:
public void onCreate(String nodeId, JsonNode config);
public void onClose(String nodeId);
public JsonNode[] onMessage(String nodeId, JsonNode msg);
Note also the use of Jackson classes to transfer Javascript objects between
domains](https://image.slidesharecdn.com/prototypingiotsystemswithahybridosginode-redplatform-brucejacksonmyriad-181108220527/85/Prototyping-IoT-systems-with-a-hybrid-OSGi-Node-RED-platform-Bruce-Jackson-Myriad-6-320.jpg)
Prototyping IoT systems with a hybrid OSGi & Node-RED platform - Bruce Jackson (Myriad)
- 1. Prototyping IoT systems with a hybrid OSGi/Node-RED platform Bruce Jackson - CTO Thingstream.io
- 2. The problem • OSGi is a widely used platform in IoT edge devices ‣ supported by multiple device vendors ‣ many reliable components have been developed for integration into northbound (enterprise) and southbound protocols/devices/etc ‣ not easy to rapidly prototype without writing code ‣ runs on the JVM • Node-red is a ‘code free’ programming environment for IoT that is very popular for prototyping ‣ easy and quick ‣ many components for common southbound protocols/devices/etc ‣ based on Node.js (V8 + Javascript)
- 4. How to combine these two different solutions? • Both systems have their advantages, but use very different technologies • However - there was a possible solution: ‣ J2V8 - an Eclipsesource project that: “We developed ... as a high performance engine for our multi-platform mobile toolkit tabris.js and it is a great choice for executing JavaScript on Android devices” • An initial test showed that it was possible to use J2V8 to create and run the Node-red environment from Java ‣ turning that into an OSGi bundle wasn’t hard ‣ for our purposes, additional V8 runtime and native bindings needed ‣ bridging code and interfaces to map OSGi components onto the Node-red lifecycle required
- 5. How does J2V8 work? Export and import values between domains: • Objects, values Register and call functions across domains: • callback functions from Java to Javascript • execute functions defined in Javascript
- 6. Mapping service interfaces to Node-red To allow OSGi components to appear as Node-red nodes, they need to implement a suitable lifecycle service interface - NodeComponent: public void onCreate(String nodeId, JsonNode config); public void onClose(String nodeId); public JsonNode[] onMessage(String nodeId, JsonNode msg); Note also the use of Jackson classes to transfer Javascript objects between domains
- 7. Demonstration • A simple node component ‣ 1 in and 1 out ‣ simple configuration for all instances • A more complex example using Paho MQTT client ‣ wrapping an existing library in a NodeComponent ‣ multiple configurations ‣ message creation
- 8. Can this work the other way around? • This example shows how OSGi services can be exported into a javascript runtime and work together ‣ although the Javascript runtime is created via OSGi, Node-red is “the boss” ‣ OSGi components play into the Node-red world • Can this work in reverse - with Javascript components in the OSGi world? • Javascript components for OSGi ‣ modularise Javascript runtime as a service (so you can implement via J2V8 or GraalVM) ‣ create component pattern for Javascript
- 9. Demonstration • A simple component model for Javascript components in the OSGi world • Javascript component registry ‣ JS components managed via a registry bundle that creates dynamic proxies over the service interface(s) they implement ‣ marshalls calls between environments ‣ exports OSGi services to the Javascript runtime through reflective call creation on Javascript objects ‣ processes bundle metadata
- 10. References and contacts OSGi: https://www.osgi.org/ Node-red: https://nodered.org/ J2V8: https://github.com/eclipsesource/J2V8 Node-red-osgi: https://github.com/brucej72/node-red-osgi Bruce Jackson: [email protected]