IO Connector Plugin

Version: 1.0

Status:

IOConnector plugin for Thunder framework.

Table of Contents

• Introduction
• Description
• Configuration
• Interfaces
• Methods
• Properties
• Notifications

Introduction

Scope

This document describes purpose and functionality of the IOConnector plugin. It includes detailed specification about its configuration, methods and properties as well as sent notifications.

Case Sensitivity

All identifiers of the interfaces described in this document are case-sensitive. Thus, unless stated otherwise, all keywords, entities, properties, relations and actions should be treated as such.

Acronyms, Abbreviations and Terms

The table below provides and overview of acronyms used in this document and their definitions.

Acronym	Description
API	Application Programming Interface
GPIO	General-Purpose Input/Output
HTTP	Hypertext Transfer Protocol
JSON	JavaScript Object Notation; a data interchange format
JSON-RPC	A remote procedure call protocol encoded in JSON

The table below provides and overview of terms and abbreviations used in this document and their definitions.

Term	Description
callsign	The name given to an instance of a plugin. One plugin can be instantiated multiple times, but each instance the instance name, callsign, must be unique.

References

Ref ID	Description
HTTP	HTTP specification
JSON-RPC	JSON-RPC 2.0 specification
JSON	JSON specification
Thunder	Thunder API Reference

Description

The IO Connector plugin provides access to GPIO pins.

The plugin is designed to be loaded and executed within the Thunder framework. For more information about the framework refer to [Thunder].

Configuration

The table below lists configuration options of the plugin.

Name	Type	M/O	Description
callsign	string	mandatory	Plugin instance name (default: IOConnector)
classname	string	mandatory	Class name: IOConnector
locator	string	mandatory	Library name: libWPEIOConnector.so
startmode	string	mandatory	Determines in which state the plugin should be moved to at startup of the framework
pins	array	mandatory	List of GPIO pins available on the system
pins[#]	object	mandatory	Pin properties
pins[#].id	integer	mandatory	Pin ID
pins[#].mode	string	mandatory	Pin mode (must be one of the following: Active, Both, High, Inactive, Low, Output)
pins[#]?.activelow	boolean	optional	Denotes if pin is active in low state (default: false)

Interfaces

This plugin implements the following interfaces:

• IIOConnector (IIOConnector.h) (version 1.0.0) (compliant format)

  This interface uses legacy lowercase naming convention. With the next major release the naming convention will change to camelCase.

Methods

The following methods are provided by the IOConnector plugin:

Built-in methods:

Method	Description
versions	Retrieves a list of JSON-RPC interfaces offered by this service
exists	Checks if a JSON-RPC method or property exists
register	Registers for an asynchronous JSON-RPC notification
unregister	Unregisters from an asynchronous JSON-RPC notification

versions ^method

Retrieves a list of JSON-RPC interfaces offered by this service.

Parameters

This method takes no parameters.

Result

Name	Type	M/O	Description
result	array	mandatory	A list ofsinterfaces with their version numbers Array length must be at most 255 elements.
result[#]	object	mandatory	...
result[#].name	string	mandatory	Name of the interface
result[#].major	integer	mandatory	Major part of version number
result[#].minor	integer	mandatory	Minor part of version number
result[#].patch	integer	mandatory	Patch part of version version number

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "IOConnector.1.versions"
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": [
    {
      "name": "JMyInterface",
      "major": 1,
      "minor": 0,
      "patch": 0
    }
  ]
}

exists ^method

Checks if a JSON-RPC method or property exists.

Description

This method will return True for the following methods/properties: pin, versions, exists, register, unregister.

Parameters

Name	Type	M/O	Description
params	object	mandatory	...
params.method	string	mandatory	Name of the method or property to look up

Result

Name	Type	M/O	Description
result	boolean	mandatory	Denotes if the method exists or not

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "IOConnector.1.exists",
  "params": {
    "method": "methodName"
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": false
}

register ^method

Registers for an asynchronous JSON-RPC notification.

Description

This method supports the following event names: activity.

Parameters

Name	Type	M/O	Description
params	object	mandatory	...
params.event	string	mandatory	Name of the notification to register for
params.id	string	mandatory	Client identifier

Result

Name	Type	M/O	Description
result	null	mandatory	Always null

Errors

Message	Description
ERROR_FAILED_REGISTERED	Failed to register for the notification (e.g. already registered)

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "IOConnector.1.register",
  "params": {
    "event": "eventName",
    "id": "myapp"
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": null
}

unregister ^method

Unregisters from an asynchronous JSON-RPC notification.

Description

This method supports the following event names: activity.

Parameters

Name	Type	M/O	Description
params	object	mandatory	...
params.event	string	mandatory	Name of the notification to register for
params.id	string	mandatory	Client identifier

Result

Name	Type	M/O	Description
result	null	mandatory	Always null

Errors

Message	Description
ERROR_FAILED_UNREGISTERED	Failed to unregister from the notification (e.g. not yet registered)

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "IOConnector.1.unregister",
  "params": {
    "event": "eventName",
    "id": "myapp"
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": null
}

Properties

The following properties are provided by the IOConnector plugin:

IOConnector interface properties:

Property	R/W	Description
pin	read/write	GPIO pin value

pin ^property

Provides access to the GPIO pin value.

The id parameter shall be passed as the index to the property, i.e. pin@<id>.

Index (Get)

Name	Type	M/O	Description
id	integer	mandatory	Pin ID

Index (Set)

Name	Type	M/O	Description
id	integer	mandatory	Pin ID

Value

Name	Type	M/O	Description
(property)	object	mandatory	GPIO pin value
(property).value	integer	mandatory	Value of the pin

Name	Type	M/O	Description
(property)	integer	mandatory	GPIO pin value

Errors

Message	Description
ERROR_UNKNOWN_KEY	Unknown pin ID given

Example

Get Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "IOConnector.1.pin@189"
}

Get Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": 0
}

Set Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "IOConnector.1.pin@189",
  "params": {
    "value": 1
  }
}

Set Response

{
    "jsonrpc": "2.0",
    "id": 42,
    "result": "null"
}

Notifications

Notifications are autonomous events triggered by the internals of the implementation and broadcasted via JSON-RPC to all registered observers. Refer to [Thunder] for information on how to register for a notification.

The following events are provided by the IOConnector plugin:

IOConnector interface events:

Notification	Description
activity	Notifies about GPIO pin activity

activity ^notification

Notifies about GPIO pin activity.

Parameters

The id parameter shall be passed as index to the register call, i.e. register@<id>.

Notification Parameters

Name	Type	M/O	Description
params	object	mandatory	...
params.value	integer	mandatory	Value of the pin

Example

Registration

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "IOConnector.1.register@189",
  "params": {
    "event": "activity",
    "id": "myid"
  }
}

Notification

{
  "jsonrpc": "2.0",
  "method": "myid.activity@189",
  "params": {
    "value": 1
  }
}

The client ID parameter is passed within the notification designator, i.e. <client-id>.activity@<id>.

The id parameter is passed as index within the notification designator, i.e. <client-id>.activity@<id>.