Low-level Tarantool driver for node.js
#Transport - low-level Tarantool driver
Transport incapsulates socket, manages callbacks, composes request headers, parses response headers, and composes response from several data packets.
Use Connector as a high-level driver or create your own.
npm install tarantool-transport
Transport.connect port, host, callback or
new Transport socket to instantiate
First way is common and preferrable while second allows to prepare
socket, mock it or hack it.
transport.request type, body, callback to send request.
typemust be Number, any valid request type: 0x0D, 0x11, 0x13, 0x15, 0x16 or 0xFF00.
bodymust be Buffer (preferrable) or String (empty string is usable, see example below).
callbackwill receive response body as Buffer, maybe empty, never
All arguments are obligatory.
Transport = require 'tarantool-transport'PING = 0xFF00 # ping request typetransport = Transportconnect porthost-> # on connectiontransportrequest PING''-> # on responseconsolelog 'got ping response'consolelog 'sent ping request'# the other way, if you want to prepare socket somehow# net = require 'net'# socket = net.connect port, host, -># # on connection# transport = new Transport socket
Before reading source please note that:
- In Tarantool, request and response headers are sequences of unsigned little-endian 32-bit integers.
- Tarantool allows to set
request_id. Server will just white this value into
response, it won't check or compare it with anything. In
transportwe call this field
callback_id— we pass callbacks and one response calls means one callback here.
transport sets up
socket in this way:
node.jsexit if we're not awaiting responses
socket.setNoDelay()to reduce latency (added in 0.2.3)
socket.on('data', cb)to parse and process responses
socket.ref() on request and
socket.unref() on last awaited response. Thus,
node.js from shutting down until it receives all responses.
This is the most common use case, but you can play with
socket in any way, at your own risk.
For those who want to hack Transport — list of inner variables:
netsocket or Object you passed to constructor
remainder— Buffer, will prepend next data chunk in order to compose responses from several data packets
callbacks— Hash (Object), keys are numeric response ids, values are passed callbacks
nextCallbackId— non-negative Number, incremented on request, when reaches 4294967296 overflows to 0, you can use it to describe request frequency
responsesAwaiting— non-negative Number, incremented on request, decremented on response, stored to know when
Bug reports and pull requests are welcome.
Tarantool Transport for node.js is published under MIT license.