sequential-ids

node-sequential-ids

A Node.js module that allows centralized generation of sequential and human-readable ids.

Sample Id: ACB - 00423

aspect	detail
version	0.0.0-alpha.4.1
dependencies	none
last updated	4th Oct, 2014

installation

From Npm:

$ npm install sequential-ids --save

usage

// assuming `db` is a variable holding a database connection with the
// method `.store(key, value)`

var sequential = require("sequential-ids");
var generator = new sequential.Generator({
  digits: 6, letters: 3,
  store: function(ids) {
    db.store("last-id", ids[ids.length - 1]);
  },
  restore: "AAB - 000"
});

generator.start();
var new_id = generator.generate(); // => AAB - 001

// possibly in another file
var accessor = new sequential.Accessor();
accessor.next(function(err, id) {
  console.log("new id: %s", id); // => AAB - 002
});

notes

1. new Generator([options])

• you only require to create a single generator instance

• options is an object having the following attributes:

  • digits:
    • no. of numbers to use in the ID.
    • numbers will be padded with zeros to satisfy this.
    • assigning 0 (zero) lets you ignore the number part
    • Defaults to 6.
  • letters:
    • no. of letters to use.
    • assigning 0 (zero) lets you ignore the letters part
    • Defaults to 3.
  • store:
    • a function that will be called to store the IDs on disk for persistence.
    • the function is passed an array of IDs that have been generated.
    • repeatedly storing the last id is useful to know where to start from in the next session.
    • Defaults to null.
  • store_freq:
    • frequency at which the store function should be called.
    • Defaults to 1(called every 1 ID is generated)
  • restore:
    • last ID that was generated.
    • IDs will be generated from here on.
    • digits and letters will be ignored so as to follow the restore ID style.
    • it must be in the same style as IDs generated by the Generator
    • If not specified, generates from start.
    • MUST be a string.
    • Defaults to null.
  • port:
    • port at which the generator serves IDs.
    • Defaults to 9876.

• in a case where you may require more than one generator, you would allocate them to different ports. See ahead on how to target each of the different generators.

var sequential = require("sequential-ids");
var generatorA = new sequential.Generator({port: 8998});
var generatorB = new sequential.Generator({port: 7667});

• A generator has the following methods:

  • Generator#start()

    • starts the generator. If no Error is thrown, the generator will be ready for Accessors.

  • Generator#generate()

    • generates a new id. The new id is returned immediately.

  • Generator#stop()

    • stops the generator. No more ids will be given to Accessors.

1. new Accessor([port])

• used to access ids.

• port is the port number of your generator. In case where, you did not specify a port when creating a Generator instance, you may leave this out. Defaults to 9876.

• an accessor may be initialized in a separate file. Ensure you got the port numbers correct.

• an accessor has the following methods:

  • Accessor#next(callback):
    • callback signature: function(err, id)
    • requests generator for a new ID.
    • The new ID is passed to the callback, on success.
  • Accessor#ping(callback)
    • callback signature: function(err)
    • pings the generator to see if it is online

• All methods are asynchronous, the Node.js way

TODO

• Robust Error handling
• Implement these features:
  • session(callback) - passes the number of IDs generated in the session.
  • .used(callback) - passes the total number of IDs generated.
  • .semantics(callback) - passes the remaining no. of ids to be generated before breaking our semantics specified while creating the generator.

contribution

• Source Code is hosted on Github
• Pull requests be accompanied with tests as in the /tests directory
• Issues may be filed here

license

Copyright (c) 2014 Forfuture LLC

Sequential Ids and its source code are licensed under the MIT license. See LICENSE file accompanying this text.