izs.js

/** Import the net nodejs package. */
var connect = require('net');

function Izs(host, port) {
    /** Field object type to define a field for Izs message fields. */
    var Field = function(name, length, value, justify) {
        if (name == null) throw new Error('a name has to be specified for a field.');
        if (length == null)  length  = 0;
        if (value == null)   value = '';
        if (justify == null) justify = 'left';
        return { name: name, length: length, value: value, justify: justify };
    };

    function Fields() {
        this.fields = [
            new Field('length', 5, '00578'), new Field('type', 3, 'ABE'),
            new Field('vendor', 10, 'BML'), new Field('product', 5, 'NODEJ'),
            new Field('terminal', 15), new Field('batch', 15), new Field('merchant', 15),
            new Field('location', 35), new Field('reference', 16),
            new Field('feeCode', 2), new Field('feeAmount', 14, '', 'right'),
            new Field('accessFee', 14, '', 'right'), new Field('timestamp', 19),
            new Field('userId', 4, 'IZS'), new Field('customerId', 10), new Field('requestType', 1, 'E'),
            new Field('debitAccount', 13), new Field('debitAccountCurrency', 3),
            new Field('debitTransactionCode', 3), new Field('debitAmount', 14, '', 'right'),
            new Field('debitNarrative1', 35), new Field('debitNarrative2', 35),
            new Field('debitNarrative3', 35), new Field('creditAccount', 13),
            new Field('creditAccountCurrency', 3), new Field('creditTransactionCode', 3),
            new Field('creditAmount', 14, '', 'right'), new Field('creditNarrative1', 35),
            new Field('creditNarrative2', 35), new Field('creditNarrative3', 35),
            new Field('exchangeRate', 25, '', 'right'), new Field('startDate', 7),
            new Field('endDate', 7), new Field('code1', 3), new Field('code2', 3),
            new Field('sequence', 3, '', 'right'), new Field('flag1', 1),
            new Field('consumerAccount', 20), new Field('serviceNumber', 20),
            new Field('billNumber', 20), new Field('mobileNumber', 10)];
    }

    /** Set the value of the specified field. If the field name is not valid throw an Error. */
    Fields.prototype.setValue = function(name, value) {
        var field = null;
        this.fields.forEach(function(e) {
            if (e.name == name) {
                e.value = value;
                field = e;
            }
        });
        if (field == null) throw new Error('invalid field name for setValue()');
    };

    Fields.prototype.serialize = function() {
        var fields = this.fields.map(function(e) {
            var value = null;
            if (e.justify == 'left')  {
                value = e.value + '                                   ';
                value = value.substring(0, e.length);
            } else if (e.justify == 'right') {
                value = '                         ' + e.value;
                value = value.substring(e.value - e.length, e.length);
            }
            return value;
        });
        return fields.join('');
    };

    /** Initialize the list of Fields. */
    this.fields = new Fields();

    /** Try connecting to Izs. */
    this.conn = connect.connect({ host: host, port: port});
    this.conn.on('error', function(error) { throw error; });
};

Izs.prototype.setValue = function(name, value) {
    this.fields.setValue(name, value);
};

Izs.prototype.request = function(onDataCallback) {
    if (typeof(onDataCallback) != 'function')
        throw new Error('the onDataCallback to request should be a function.');
    this.conn.on('data', onDataCallback);
    this.conn.write(this.fields.serialize());
};

Izs.prototype.close = function() {
    this.conn.end();
};

module.exports = Izs;

test-izs.js

var izs = require('./izs.js');

var client = new izs('172.16.1.11', 5125);
client.setValue('reference',            '123');
client.setValue('debitAccount',         '7703217955101');
client.setValue('debitAccountCurrency', 'MRF');
client.setValue('debitTransactionCode', '010');
client.setValue('debitAmount',          '1400');

client.request(function(data) {
    console.log(data.toString());
});