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1. Overview

lwm2m-id is a dictionary of identifiers defined by OMA LightweightM2M(v1.0), IPSO SmartObject Guideline(Smart Objects Starter Pack1.0 and Smart Objects Expansion Pack). Please visit their websites for more information.


2. Installation

$ npm install lwm2m-id --save


3. Usage

lwm2m-id provides you with two getters, i.e. getOid() and getRid(), to get the key-value pair of an Object and a Resource identifier. The getter returns an item which has properties of 'key' and 'value', or returns undefined if not found. In the returned item, item.key is the idetifier in string and item.value is the identifier in number.

Let me show you some examples.

var lwm2mid = require('lwm2m-id')

// get Object Id
var oidItem1 = lwm2mid.getOid('device');                // { key: 'device', value: 3 }
var oidItem2 = lwm2mid.getOid(3);                       // { key: 'device', value: 3 }
var oidItem3 = lwm2mid.getOid('3');                     // { key: 'device', value: 3 }
var oidItem4 = lwm2mid.getOid(999);                     // undefined
var oidItem5 = lwm2mid.getOid('noSuchId');              // undefined

var oidKey = lwm2mid.getOid(3).key;                     // 'device'
var oidId = lwm2mid.getOid('device').value;             // 3

// get Resource Id
//   (1) The rid is specific to an Object
var ridItem1 = lwm2mid.getRid('lightCtrl', 'onOff');    // { key: 'onOff', value: 5850 }
var ridItem2 = lwm2mid.getRid(3311, 'onOff');           // { key: 'onOff', value: 5850 }
var ridItem3 = lwm2mid.getRid(3311, 5850);              // { key: 'onOff', value: 5850 }
var ridItem4 = lwm2mid.getRid('3311', '5850');          // { key: 'onOff', value: 5850 }
var ridItem5 = lwm2mid.getOid('lightCtrl', 'noSuchId'); // undefined
var ridItem6 = lwm2mid.getOid('noSuchId', 5850);        // undefined

var ridKey = lwm2mid.getRid('lightCtrl', 5850).key;     // 'onOff'
var ridId = lwm2mid.getRid(3311, 'onOff').value;        // 5850

//   (2) The rid is an unique id
var ridItem7 = lwm2mid.getRid('sensorValue');           // { key: 'sensorValue', value: 5700 }
var ridItem8 = lwm2mid.getRid(5700);                    // { key: 'sensorValue', value: 5700 }
var ridItem8 = lwm2mid.getRid('5700');                  // { key: 'sensorValue', value: 5700 }

var ridKey = lwm2mid.getRid(5700).key;                  // 'sensorValue'
var ridId = lwm2mid.getRid('sensorValue').value;        // 5700

4. APIs


.getOid(oid)

Returns an item of the Object identifier.

Arguments

  1. oid (String|Number): oid can be given with a string or a number. Notice that a numbered string will be recognized as a number, e.g. '128' is equal to 128.

Returns:

  • (Object | Undefined) Returns an item of { key: 'sampleId', value: 1234 }, otherwise returns undefined if not found.

Example

lwm2mid.getOid('temperature');  // { key: 'temperature', value: 3303 }
lwm2mid.getOid(3303);           // { key: 'temperature', value: 3303 }
lwm2mid.getOid('3303');         // { key: 'temperature', value: 3303 }

lwm2mid.getOid('xxxx');         // undefined 
lwm2mid.getOid('9999');         // undefined 
lwm2mid.getOid(9999);           // undefined


.getRid([oid,] rid)

Returns an item of the Resource identifier.

There are two kinds of Resource id, the unique Resource id and the Resource id specific to an Object. An Object can use both of these two kinds of Resource id to define its characteristic.

  • Unique Resource id
    • Resouce id is a reusable one and its id number is always constant and unique across Objects.
    • To query an unique Resource id, only the single argument rid is needed.
  • Resource id specific to an Object
    • The meaning of a Resource is specific to an Object that holds it.
    • To query a Resource id specific to an Object, both oid and rid should be given.

Arguments

  1. oid (String|Number, optional): oid can be given with a string or a number. Notice that a numbered string will be recognized as a number, e.g. '128' is equal to 128.
  2. rid (String|Number): rid can be given with a string or a number. Notice that a numbered string will be recognized as a number, e.g. '128' is equal to 128.

Returns:

  • (Object | Undefined) Returns an item of { key: 'sampleId', value: 1234 }, otherwise returns undefined if not found.

Example

// get a Resource id specific to an Object
lwm2mid.getRid('location', 'lon');             // { key: 'lon', value: 1 }
lwm2mid.getRid(6, 1);                          // { key: 'lon', value: 1 }
lwm2mid.getRid('temperature', 'sensorValue');  // { key: 'sensorValue', value: 5700 }
lwm2mid.getRid(3303, 5700);                    // { key: 'sensorValue', value: 5700 }
lwm2mid.getRid('temperature', '5700');         // { key: 'sensorValue', value: 5700 }

// get an unqiue Resource id
lwm2mid.getRid('appType');                     // { key: 'appType', value: 5750 }
lwm2mid.getRid(5750);                          // { key: 'appType', value: 5700 }
lwm2mid.getRid('5750');                        // { key: 'appType', value: 5750 }


.getOdef(oid)

Returns the sepc. definitions of an Object.

Arguments

  1. oid (String|Number): oid can be given with a string or a number. Notice that a numbered string will be recognized as a number, e.g. '128' is equal to 128.

Returns:

  • (Object | Undefined) Returns the definition with an data object, otherwise returns undefined if not found. The definition object is of the form: { multi: false, mand: true }
Property Description Possible Settings
multi Allow multiple instances true, false
mand Mandatory true, false

* Please refer to Appendix in OMA LightweightM2M(v1.0) specification for details.

Example

lwm2mid.getOdef('temperature');  
// returns { "multi": true, "mand": false }
  
lwm2mid.getOdef('lightCtrl');  
// returns { "multi": true, "mand": false }

lwm2mid.getOdef('device');  
// returns { "multi": false, "mand": true }

lwm2mid.getOdef('xxxx');            // undefined


.getRdef(oid, rid)

Returns the definitions of a Resource specific to an Object.

Arguments

  1. oid (String|Number, optional): oid can be given with a string or a number. Notice that a numbered string will be recognized as a number, e.g. '128' is equal to 128.
  2. rid (String|Number): rid can be given with a string or a number. Notice that a numbered string will be recognized as a number, e.g. '128' is equal to 128.

Returns:

  • (Object | Undefined) Returns the definition with an data object, otherwise returns undefined if not found. The definition object is of the form: { access: null, multi: false, mand: true, type: "boolean", range: null, init: false }
Property Description Possible Settings
access Access control 'R', 'W', 'RW', 'E', null (cannot access)
multi Allow multiple instances true, false
mand Mandatory true, false
type* Resource value data type 'boolean', integer', 'float', string', 'time', execute', 'opaque'
range Limit of Resource value A number, null if no limit.

* Please refer to Appendix C. Data Types in OMA LightweightM2M(v1.0) specification for details.

Example

lwm2mid.getRdef('temperature', 'sensorValue');  
// returns { "access": "R", "multi": false, "mand": true, "type": "float", "range": null }
  
lwm2mid.getRdef('lightCtrl', 5850);  
// returns { "access": "RW", "multi": false, "mand": true, "type": "boolean", "range": null }

lwm2mid.getRdef('temperature');     // undefined. rid should be given
lwm2mid.getRdef('xxxx', 1234);      // undefined
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