WoT Runtime, Scripting, Bindings Zoltan Kis, Intel W3C Web of - - PowerPoint PPT Presentation

WoT Runtime, Scripting, Bindings

Zoltan Kis, Intel W3C Web of Things WG meeting in Osaka, Japan 17 May 2017

Things Things TDs Scripting API (client, server, discovery) WoT Runtime

Manager Thing

System APIs plugin iface Protocol Binding 1..x plugin iface Legacy/HW API 1..y plugin iface System API 1..z plugin iface Service Proxy 1..s

System Things

Local Sensors HW access Secure Storage File System TDs, scripts Protocol Service 1 (OCF) Protocol Service 2 (BLE)

OS/HW

Process view

• WoT RT: process
• Script execution contexts
• Bindings: separate processes
• System APIs / OS Kernel

Special Things

• Script Manager Thing
• System Access Things

○ expose API objects ○ have TDs ⇒ discoverable (introspection) System APIs

• Protocol stack/services

(CoAP, HTTP, BLE, OCF, ...)

• file system
• secure storage
• local sensors
• Local HW API

WoT Stack

Execution context 1 Execution context n Script 1..n Script 1..m Runtime Core (process)

Things Things TDs Scripting API (client, server, discovery) WoT Runtime

Manager Thing

System APIs plugin iface Protocol Binding 1..x plugin iface Legacy/HW API 1..y plugin iface System API 1..z plugin iface Service Proxy 1..s

System Things

Local Sensors HW access Secure Storage File System TDs, scripts Protocol Service 1 (OCF) Protocol Service 2 (BLE)

OS/HW

WoT Runtime

Execution context 1 Execution context n Script 1..n Script 1..m Runtime Core (process) Script Execution Context (SEC)

• Single event/main loop
• May run multiple scripts
• Serialized execution
• Hosts multiple Thing instances

SEC Definitions

• For ECMAScript (in browsers):
• Multiple SEC
• One SEC exec’d at a time
• For WoT: more like in Node.js
• SEC may be sandboxed

Runtime Core

• Process hosting all structures
• API objects (client, server…)
• System API objects
• Bindings plugin host
• special Things
• May spawn new SECs
• Security enforcement point

(trusted)

Scripts use the Scripting API to interact with

• local and remote Things
• special Things:

○ System APIs, via System Things + bindings) ○ Script Manager Thing (save, delete, run, stop, make persistent…) Scripts can get to the device by:

• Manager Thing
• Provisioned (e.g. flashed)
• By consuming a TD

TDs may contain scripts for

• Event handlers
• Action handlers

WoT Scripting

Script 1 Script n Things Things TDs Scripting API WoT Runtime Runtime Core Manager Thing System Things System API plugin iface Protocol Binding 1..x plugin iface Legacy/HW API 1..y plugin iface System API 1..z plugin iface Service Proxy 1..s

network→ system/socket→ binding→ runtime→ → manager/action → run script → API→ runtime → [fetch TD: system APIs→ → bindings→ socket→ → runtime→ API→ TD] → → create Thing + bind to RT → manager/reply → bindings→ system/socket → network. Scripts produce runtime bound Thing instances [+ TDs], each having:

• Properties + getters/setters
• Event handlers
• Action handlers
• Mappings to Bindings

Request to run script

Script 1 Script n Things Things TDs Scripting API WoT Runtime Runtime Core Manager Thing System Things System API plugin iface Protocol Binding 1..x plugin iface Legacy/HW API 1..y plugin iface System API 1..z plugin iface Service Proxy 1..s

network→ socket→ OS → binding→ runtime→ Thing (process, reply) → API → binding→ OS → socket→ network Thing instances use the Scripting API implementation through event and action handler functions registered with the Runtime Core. The Runtime Core maps handlers to Protocol/System/Legacy/Service Bindings.

Request to access a Thing

Things Things Scripting API WoT Runtime Runtime Core System Things System API plugin iface Protocol Binding 1..x plugin iface Legacy/HW API 1..y plugin iface System API 1..z plugin iface Service Proxy 1..s TDs