node-l

node-l

L interfacing with Node.js. Can deserialize all q data types (including guid) to JavaScript. Can serialize all JavaScript data types to q.

Installation

npm install node-l

Usage

Create Connection

var nodeq = require("node-l");
nodeq.connect({host: "localhost", port: 5000}, function(err, con) {
	if (err) throw err;
	console.log("connected");
	// interact with con like demonstrated below
});

Create Connection with user and password auth

var nodeq = require("node-l");
nodeq.connect({host: "localhost", port: "localhost", 5000, user: "user", password: "password"}, function(err, con) {
	if (err) throw err;
	console.log("connected");
	// interact with con like demonstrated below
});

Execute Q code and receive result

con.k("sum 1 2 3", function(err, res) {
	if (err) throw err;
	console.log("result", res); // 6
});

Execute function with one parameter and receive result

con.k("sum", [1, 2, 3], function(err, res) {
	if (err) throw err;
	console.log("result", res); // 6
});

Execute function with two parameters and receive result

con.k("cor", [1, 2, 3], [4, 5, 6], function(err, res) {
	if (err) throw err;
	console.log("result", res); // 1
});

Async execute Q code

con.ks("show 1 2 3", function(err) {
	if (err) throw err;
});

Async execute function with parameters

con.ks("show", [1, 2, 3], function(err) {
	if (err) throw err;
});

Subscribe to kdb+tick

con.on("upd", function(table, data) {
	console.log(table, data);
});

con.ks(".u.sub[`;`]", function(err) { // subscribe to all tables and all symbols
	if (err) throw err;
});

Close connection

con.close(function() {
	console.log("con closed");
});

Types

q has more data types than JavaScript. Therefore you need to know how types are converted.

From q to JavaScript (deserialization)

q type	JavaScript type	Null	+Infinity	-Infinity
boolean	Boolean
guid	String	Null
byte	Number
short	Number	Null	Infinity	-Infinity
int	Number	Null	Infinity	-Infinity
long	Number 5	Null	Infinity	-Infinity
real	Number	Null	Infinity	-Infinity
float	Number	Null	Infinity	-Infinity
char	String	Null 4
symbol	String	Null
timestamp	Date 1, 2	Null
month	Date 2	Null
date	Date 2	Null
datetime	Date 2	Null
timespan	Date 1, 2, 3	Null
minute	Date 2, 3	Null
second	Date 2, 3	Null
time	Date 2, 3	Null

• 1: q comes with nanoseconds precision. JavaScript only with milliseconds. You can disable nanos2date deserialization during connect(params, cb) to get the nanoseconds timestamp as a plain Number.
• 2: think about running your Node.js process with TZ=UTC node ... to run in UTC timezone. q doesn't know timezones.
• 3: date is set to 2000-01-01 in the Date object. Only evaluate the time part.
• 4: You can disable emptyChar2null deserialization during connect(params, cb) to keep the empty char.
• 5: You can disable long2number deserialization during connect(params, cb) to represent longs as long.js.

dict

q) (`a`b`c)!(1 2 3i)

becomes Object

{
	a: 1,
	b: 2,
	c: 3
}

list

q) 1 2 3i

becomes Array

[1, 2, 3]

table

q) ([] sym:`a`b`c; size:(1 2 3i))

becomes Array of Object per row.

[
	{sym: "a", size: 1},
	{sym: "b", size: 2},
	{sym: "c", size: 3}
]

You can disable flipTables during connect(params, cb) to get a table as an Object with an Array per column.

{
	sym: ["a", "b", "c"],
	size: [1, 2, 3]
}

From JavaScript to q (serialization)

Simple (infer type)

JavaScript type	q type
Boolean	boolean
String starting with `	symbol
String	list[char]
Number	float
Date	datetime
Object	dict
Array[*]	list[*]
Null	unary primitive
Infinity	float
-Infinity	float

Advanced (explicit types)

If you want to explicitly serialize a JavaScript type as a q type you need to use the typed API.

Let's start with two examples:

con.k("type", nodeq.short(1), function(err, res) {
	if (err) throw err;
	console.log("result", res); // -5
});

con.k("type", nodeq.shorts([1, 2, 3]), function(err, res) {
	if (err) throw err;
	console.log("result", res); // 5
});

For every primitive type in q, this module exports a method to wrap the JavaScript value. You can also wrap a JavaScript array into a q type by appending an s to the primitive wrapper's name.

q type	primitive wrapper	array wrapper
boolean	boolean(Boolean)	booleans(Array[Boolean])
guid	guid(String)	guids(Array[String])
byte	byte(Number)	bytes(Array[Number])
short	short(Number)	shorts(Array[Number])
int	int(Number)	ints(Array[Number])
long	long(long) 1	longs(Array[long]) 1
real	real(Number)	reals(Array[Number])
float	float(Number)	floats(Array[Number])
char	char(String)	chars(Array[String])
symbol	symbol(String)	symbols(Array[String])
timestamp	timestamp(Date)	timestamps(Array[Date])
month	month(Date)	months(Array[Date])
date	date(Date)	dates(Array[Date])
datetime	datetime(Date)	datetimes(Array[Date])
timespan	timespan(Date)	timespans(Array[Date])
minute	minute(Date)	minutes(Array[Date])
second	second(Date)	seconds(Array[Date])
time	time(Date)	times(Array[Date])

• 1: JavaScript can not represent 64bit longs. Therefore this module uses the long.js module to represent longs.

API

connect(params, cb)

• params: Object
  • host: String (e. g. "localhost")
  • port: Number (e. g. 5000)
  • user: String (optional)
  • password: String (optional)
  • socketNoDelay : Boolean (optional, see http://nodejs.org/api/net.html#net_socket_setnodelay_nodelay)
  • socketTimeout: Number (optional, see http://nodejs.org/api/net.html#net_socket_settimeout_timeout_callback)
  • nanos2date: Boolean (optional, default: true)
  • flipTables: Boolean (optional, default: true)
  • emptyChar2null: Boolean (optional, default: true)
  • long2number: Boolean (optional, default: true)
• cb: Function(err, con)
  • err: Error or undefined
  • conn: Connection or undefined

@deprecated connect(host, port, [user, password,] cb)

This is deprecated. Please use the new, mor flexible API above!

• host: String (e. g. "localhost")
• port: Number (e. g. 5000)
• user: String (optional)
• password: String (optional)

Connection

Is an EventEmitter.

k(s, [x, [y, [z, [...,] ] ] ] cb)

Sync request/response.

• s: String
• x: Object (optional)
• y: Object (optional)
• z: Object (optional)
• ...: Object (optional)
• cb: Function(err, res)
  • err: Error or undefined
  • res: Object or undefined

ks(s, [x, [y, [z, [...,] ] ] ] cb)

Async request.

• s: String
• x: Object (optional)
• y: Object (optional)
• z: Object (optional)
• ...: Object (optional)
• cb: Function(err)
  • err: Error or undefined

close(cb)

• cb: Function(err) (optional)
  • err: Error or undefined

Events

upd(table, data)

If you use kdb+tick and subscribe like con.ks(".u.sub[;]", function(err) { throw err; }) you will receive all Updates via upd Event.

• table: String (e.g. trades)
• data: Object (table represented in JavaScript as Array of Object)

error(err)

If the socket emit an error event.

• err: Error

end()

If the socket emit an end event.

timeout()

If the socket emit a timeout event.

close(had_error)

If the socket emit a close event.

• had_error: Boolean (true if the socket had a transmission error)

Contribution

If you want to create a Pull-Request please make sure that make test runs without failures.

If you have a kdb+tick setup please also run make mochait.

Code Style

make jshint

Unit Tests

make mocha

Integration Test

Assumes running kdb+tick process on localhost:5000!

make mochait

Circular depdendencies

make circular