Create unique and reusable identifiers as buffers or arrays
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README.md

buffer-id

Build Status

Install

npm install buffer-id

Create unique and reusable identifiers as buffers or arrays.

Example ids created by this module:

  • [0,0,0] (as buffer <00 00 00>)
  • [0,1] (as buffer <00 01>)
  • [0,0,0,0,255] (as buffer <00 00 00 00 ff>)

Use

Create store and pass some options to it. For example idStore with options:

  • idLength = 3
  • indexRange = 256

will be able to create ids of length 3 where first id will be [0,0,0] and last [255,255,255]. That gives 16777216 possible ids.

// Require module
const BufferId = require('buffer-id');

// Create idStore
const idStore = new BufferId({
    idLength: 3,
    indexRange: 256
});

// Create id as array
const id = idStore.create(); // [0,0,0] 

// Create another id
const id2 = idStore.create(); // [0,0,1]

// Remove id from idStore and release it
idStore.remove(id2); 

// Create new id [0,0,1], since we released it in previous step 
const id3 = idStore.create(); // [0,0,1] 

Options

idLength - length of id

type required
Number true

indexRange - specifies maximum values of each part of id

type required default
Number false 256

Note that starting value is always 0, so range 256 will allow values form 0 to 255. If ids are intended to use as buffer there is no point setting indexRange greater than 256.

For example if idLength is set to 3:

  • indexRange = 256 will produce ids from [0,0,0] (<00 00 00> as buffer) to [255,255,255] (<ff ff ff> as buffer) (that gives 16777216 ids)
  • indexRange = 10 will produce ids from [0,0,0] (<00 00 00> as buffer) to [9,9,9] (<09 09 09> as buffer) (that gives 1000 ids)

idFormat - default format of ids (can be array or buffer)

type required default
String [buffer|array] false array

Methods

create

Creates new id. New id is either buffer or array (depends on store settings).

remove

Params:

name type required
id array | buffer true

Removes id from store, so it can be reused.

Implementation

Tree is used as internal structure of idStore. Animation shows creating and removing id when idLength is 3 and indexRange is 3. Identifiers are from range [0,0,0] to [2,2,2].

implementation of buffer-id

Use case

This module can be used to create buffer ids which we can be sent to some service alongside with buffer message.

Lets say we have two microservices A and B, which can communicate using strings and buffers. Sending file from A to B could look like that:

  1. A to B: "I am about to send file named cat.jpg",
  2. B to A: "Ok, send it with id [0,0,0],

Then on the side of A:

// we have cat.jpg in variable named cat
const id = Buffer.from([0,0,0]); // creates <Buffer 00 00 00>
const msg = Buffer.concat([id, cat]); // Ads id just before cat
  1. A to B: <Buffer 00 00 00 ff d2 03 04 ... e5 06 0f 08>
  2. B gets the message. Knowing that first 3 bytes is id it extracts cat from message and saves it as cat.jpg.

Test

AVA is used for testing. To run tests just type command:

npm run test