bin-protocol

bin-protocol

bin-protocol is a library for parsing and creating arbitrary byte buffers. It was created for Apache Kafka client.

You can build your own type definitions based on the following methods:

• Int8
• UInt8
• Int16LE
• UInt16LE
• Int16BE
• UInt16BE
• Int32LE
• Int32BE
• UInt32LE
• UInt32BE
• FloatLE
• FloatBE
• DoubleLE
• DoubleB

Int64 support (using long.js):

• Int64BE
• Int64LE

Read or write raw bytes:

• raw

Loops (arrays):

• loop

Install

$ npm install bin-protocol

Reader examples

Built-in metods:

var protocol = require('bin-protocol');

var reader = new protocol.Reader(new Buffer([0, 1, 2, 3]));

reader
    .Int8('num1')
    .Int8('num2')
    .Int8('num3')
    .Int8('num4');

console.log(reader.result); // => { num1: 0, num2: 1, num3: 2, num4: 3 }

Define custom 'char' and 'array' methods:

var protocol = require('bin-protocol');

protocol.define('char', {
    read: function () {
        this.Int8('char');
        return String.fromCharCode(this.context.char); // convert from char code to character
    }
});

protocol.define('array', {
    read: function () {
        this
            .Int8('length')
            .loop('items', this.char, this.context.length); // read 'length' characters with above defined 'char' method
        return this.context.items; // return just items, without 'length' property
    }
});

var reader = new protocol.Reader(new Buffer([5, 97, 98, 99, 100, 101]));

reader.array('chars');

console.log(reader.result); // => { chars: [ 'a', 'b', 'c', 'd', 'e' ] }

Writer examples

var writer = new protocol.Writer();

writer
    .Int8(1)
    .Int8(2)
    .Int8(3);

var buffer = writer.result();

console.log(buffer); // => <Buffer 01 02 03>

Define an array data type which first writes data array length as a single byte

protocol.define('array', {
    write: function (values) {
        this
            .Int8(values.length)
            .loop(values, this.Int8); // write all values with Int8 method
    }
});

var writer = new protocol.Writer();

writer.array([2, 3, 4]);

console.log(writer.result()); // => <Buffer 03 02 03 04>

Define reader and writer methods together, this one writes (or reads) raw buffer preceeded by its length as 32 bit integer.

protocol.define('bytes', {
    read: function() {
        this.Int32BE('length');
        if(this.context.length <= 0){
            return null;
        }
        this.raw('value', this.context.length);
        return this.context.value;
    },
    write: function(value) {
        if (value === undefined || value === null) {
            this.Int32BE(-1);
        } else {
            if(Buffer.isBuffer(value) || typeof value === 'string'){
                this
                    .Int32BE(value.length)
                    .raw(value);
            } else {
                throw new Error('Kafka bytes value should be a Buffer or String');
            }
        }
    }
});

Loops (arrays)

All next 3 examples are essentialy identical:

Read data with your own code:

protocol.define('customArray', {
    read: function () {
        var i = 0;
        this.Int32BE('length');

        for(i = 0; i<this.context.length; i++){
            this.Int32BE('items[' + i + ']'); // yes, this works
        }

        return this.context.items;
    }
});

Read with .loop() method by providing the length (loop count):

protocol.define('loopArray', {
    read: function () {
        this
            .Int32BE('length')
            .loop('items', this.Int32BE, this.context.length);
        return this.context.items;
    }
});

Read with .loop() method until the end() is called:

protocol.define('loopArrayEnd', {
    read: function () {
        var len;
        this.Int32BE('length');
        len = this.context.length;
        this.loop('items', function (end) {
                this.Int32BE();
                if((len -= 1) === 0){
                    end(); // call end() to break from loop
                }
            });
        return this.context.items;
    }
});

See Kafka protocol for more examples.

License (MIT)

Copyright (c) 2015 Oleksiy Krivoshey.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.