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Node.js

Node.js® is a JavaScript runtime built on Chrome's V8 JavaScript engine. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient. Node.js' package ecosystem, npm, is the largest ecosystem of open source libraries in the world.

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What technologies are best suited for the highest performance web services to handle the heaviest loads? Thousands (even millions) of transactions per second?

I know that Node.js can handle thousand(s) sessions on a single thread. And I do not know of any other technology which handle more than one session per thread. Am I right about that? Are there others that can do this also?

What about real-time programming as it relates to web-services. Is there such a thing?

And how about a few general words about hardware deployment? Having a central API call which distributes calls to hundreds of more specialized web servers? What about Caching for successive related calls?

And what about Machine Learning? Can algorithms be optimized by existing Machine Learning algorithms that reduce the average response times of the most heavily load web service?

Thanks.
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Learn how to optimize MySQL for your business need
LVL 3
Learn how to optimize MySQL for your business need

With the increasing importance of apps & networks in both business & personal interconnections, perfor. has become one of the key metrics of successful communication. This ebook is a hands-on business-case-driven guide to understanding MySQL query parameter tuning & database perf

jquery
node.js
css
javascript
html5

great to learn on w3schools.com because code editor is provided and examples are short


is there another w3schools.com so I can become a better beginner
not looking for 500+ characters code samples where i create entire websites
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I updated node and npm and now yo is not working. I installed it in many ways including sudo npm install -g yo.

It does install and runs the yo doctor. Everything checks out. But when I type yo doctor, it says

-bash: yo: command not found

Im wondering if it has to do with my path and node. I even tried to brew link node and have done many steps. Not sure what else to do so asking the experts!

Thank you all.
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Hello All,

I am reading a book called express.js Blueprints.  I am trying to wrap my mind around understanding authentication using passport.  serializing and deserializing is not registering to me.  I have just started learning node and express js so that's a big reason why.

Here's a code from the book on setting up passport.  Starting with line 5, can someone please break down what's happening?  Where is the "user" parameter coming from in the serializeUser function?  Where did "user.id" come from?

var passport = require('passport');
var LocalStrategy = require('passport-local').Strategy;
var User = require('mongoose').model('User');

passport.serializeUser(function(user, done) {
done(null, user.id);
});
passport.deserializeUser(function(id, done) {
User.findById(id, done);
});

passport.use(new LocalStrategy(function(email, password, done) {
User.findOne({
email: email
}, function(err, user) {
if (err) return done(err);
if (!user) {
return authFail(done);
}
if (!user.validPassword(password)) {
return authFail(done);
}
return done(null, user);
});
}));

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Hi Guys/Girls i'm having trouble with an exchange server, I am trying to upgrade to CU17.

Host is Server 2012R2

i have prepared AD via;

setup.exe /PrepareAD /IAcceptExchangeServerLicenseTerms
setup.exe /PrepareSchema /IAcceptExchangeServerLicenseTerms

then once running the setup for CU17 i get through all pre req checks etc, get too around 94% and the process hangs before Exchange will finally tell me upgrade has failed with this error;

Error occurreSystem.Exception: Failure configuring SearchFoundation through installconfig.ps1 - Error occurred while configuring Search Foundation for Exchange.System.TimeoutException: Timed out waiting for Admin node to be up and running

I have googled, until i can no longer google. Only references i see are firewall issues or permissions issue, none of which are a problem for me, firewall is off, and i am using full permissions.

I think the problem has something to do with my Exchange HostControllerService, It will start but stops immediately after, event viewer reports no problems in regards to it.

I Noticed OWA also will not search mail, So sure that these two problems are related, With search issues i normally expect database index state, but all is healthy.

im all out of things to try, was hoping for some advice. Cheers.
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Hi everyone,
                      my tsm 6.4  backup is failing with the message: ANS0326E This node has exceeded its maximum number of mount points.


any idea or steps to solve this issue?

Thanks in advance.

Santiago.
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I havecreated a node.js express app using pdfkit to create dynamic PDFs.  I need to set the color as a Spot color, or at least 100% Black using CMYK for my workflow purposes.

The documentation for pdfkit shows only hex values as possible (#00000, #ff0000, etc...).  Does anyone know if it is possible to set a CMYK or Spot color?
0
-------my code-----

import xml.dom
import xml.dom.minidom
doc = xml.dom.minidom.parseString('''
<root>
   <person id="01">
      <name> abc</name>
      <age>32</age>
      <address>addr123</address>
      <siblings>
        <name></name>
        <name></name>
      </siblings>
   </person>
   <person id="02">
      <name> def</name>
      <age>44</age>
      <address>addr456</address>
      <siblings>
        <name></name>
        <name></name>
        <name></name>
      </siblings>
   </person>
</root>

''')


def innerHtml(root):
    text = ''
    nodes = [ root ]
    while not nodes==[]:
        node = nodes.pop()
        if node.nodeType==xml.dom.Node.TEXT_NODE:
            text += node.wholeText
        else:
            nodes.extend(node.childNodes)
    return text

for statusNode in doc.getElementsByTagName('person'):
    for childNode in statusNode.childNodes:
        if childNode.nodeType==xml.dom.Node.ELEMENT_NODE:
            print("{}={}".format(childNode.nodeName, innerHtml(childNode)))

-------------output i got is------------------
name= abc
age=32
address=addr123
siblings=
                     
name= def
age=44
address=addr456
siblings=

---------but expected output should be in tableformat-----
i need to get the person id attribute also...pls answer

person id         name         age      address
01                abc          32      addr123
02                def          44       addr456
0
Team, I need some help diagnosing this issue, asked by one of our DBA's, server is part of a cluster, the cluster was manually failed over to the other node around the time this issue/error occurred?
errorSQL.png
Message
Login failed for user 'XXX\WINXXXX$'. Reason: Token-based server access validation failed with an infrastructure error. Check for previous errors. [CLIENT: XX.XXX.XX.XX] - Any ideas where/how I diagnose what the issue is here?

Many thanks
0
I have this function 'loadSong' that I got from an example on the net. It works fine.

I now want to make 'songName' assigned the value retrieved from a QueryString, such as
localhost:3000?songName=Imagine

How can I do that please?

This is a Node.js application I have running on my local machine where I am testing. Eventually it will be on a Node hosting plan (Heroku).

Thanks!



function loadSong(songName) {
    resetAllBeforeLoadingANewSong();

    // This function builds the current
    // song and resets all states to default (zero muted and zero solo lists, all
    // volumes set to 1, start at 0 second, etc.)
    currentSong = new Song(songName, context);

// I NEED THE VARIABLE songName to be the value of a querystring. For example, from
// localhost:3000?songName=Imagine

// THE REST OF THE CODE IS INFO ONLY



    var xhr = new XMLHttpRequest();
    xhr.open('GET', currentSong.url, true);

    xhr.onload = function (e) {
        // get a JSON description of the song
        var song = JSON.parse(this.response);

        // resize canvas depending on number of samples
        resizeSampleCanvas(song.instruments.length);

        // for eah instrument/track in the song
        song.instruments.forEach(function (instrument, trackNumber) {
            // Let's add a new track to the current song for this instrument
            currentSong.addTrack(instrument);

            // Render HTMl
            var span = document.createElement('tr');
         

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0
Will your db performance match your db growth?
LVL 3
Will your db performance match your db growth?

In Percona’s white paper “Performance at Scale: Keeping Your Database on Its Toes,” we take a high-level approach to what you need to think about when planning for database scalability.

Hi, please need guidance on how to fix the npm error. Thanks so much in advance.

# rpm --query centos-release
centos-release-6-6.el6.centos.12.2.x86_64

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# node --version
v0.10.48

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# npm --version

module.js:340
    throw err;
          ^
Error: Cannot find module 'npmlog'
    at Function.Module._resolveFilename (module.js:338:15)
    at Function.Module._load (module.js:280:25)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at /usr/lib/node_modules/npm/bin/npm-cli.js:18:11
    at Object.<anonymous> (/usr/lib/node_modules/npm/bin/npm-cli.js:86:3)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)

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Hello,

I am very new to nodejs but have been learning a lot these past few weeks.  I am trying to use passport to implement authentication but I am getting an error that I need to fix.  Any assistance would be much appreciated.  Here is the error I get..
node error
Below is part of my code:

index.js
const express = require('express');
const mongoose = require('mongoose');
const hbs = require('express-handlebars');
const bodyParser = require('body-parser');
const cookieParser = require('cookie-parser')
const passport = require('passport')
const LocalStrategy = require('passport-local').Strategy
var User = require('./models/account')

mongoose.connect('mongodb:cluster0-shard-00-00-yng8g.mongodb.net:27017,cluster0-shard-00-01-yng8g.mongodb.net:27017,cluster0-shard-00-02-yng8g.mongodb.net:27017/vendorCollection?ssl=true&replicaSet=Cluster0-shard-0&authSource=admin');


app.use(cookieParser())
//Persists data in memory inside of application
app.use(require('express-session')({
    secret: 'vendorSecret',
    resave: false,
    saveUninitialized: false
}))
app.use(passport.initialize())
app.use(passport.session())

//Allows you to use static files
app.use(express.static('public'))

app.use('/vendor', vendorRouter)
app.use('/admin', adminRouter)

passport.use( new LocalStrategy(User.authenticate()) )     //<---Error on this line
passport.serializeUser(User.serialize())
passport.deserializeUser(User.deserialize())

app.listen(3000, ()=>{
  console.log("Server Listening");
})

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0
Hi, I got this Multitrack Player to work on Node.js on a Node hosting service heroku.com
https://github.com/squallooo/MT5
I also got it to work locally on my PC.

I have Wordpress hosting at Dreamhost.

Now I want to include the Multitrack Player into the Wordpress page.
I need some help with that.

For a start, how can I simply 'insert' the player into my WP page?

Thanks.
0
Hi experts,
aI'm trying to update nodejs version , i try this command lines :
f.png
I don't understand why  it can't be updated
PS: am using linux mint 17.2
0
Hello Experts,

I have a webpage and I need to get the data from a postgres db.  I will probably hire someone to actually do this, but I'd like to understand the process prior.  I think that I have to use node.js to get the data from the database.  Does that sound right?  Or is there a better way to get at the data?
0
HI experts ,
I have to  update nodejs version. I checked several links but  noway .  
This  is  the last link i tried


But  i find the same nodejs version
f.pngps : am using linux mint 17.2

Thankx for help .
0
I successfully got this example to work on my Windows 10 pc. (thanks to help from Expert it_saige)
https://www.experts-exchange.com/questions/29039118/Running-a-Hello-World-on-Node-js-on-Windows-10-newbie.html?anchor=a42185760¬ificationFollowed=191140277#a42185760

I now want to host it on a GoDaddy hosting account I just signed up for.

I've never setup a Node.js website before - though I have worked with IIS/ASP sites for years.
Is it just a matter of copying the files to a particular folder (eg. root)?

Thanks for any help.
0
I'm trying to run this example here https://github.com/squallooo/MT5 (of an HTML5 application)

It needs to run on Node.js - I am unfimilar with Node.js. (though ok with IIS)

I have downloaded Node.js and installed it. I have downloaded the ZIP file from GitHub.

Can someone please give me a step-by-step to enable me to open/run this one-page web file?

A demo is here http://mainline.i3s.unice.fr/
(pretty cool if you're a musician)

Thanks
0
I am trying to connect to MongoDB in mongoDBatlas from my javascript but I keep getting the following error.

MongoError: connection 5 to isaaccluster-shard-00-02-yng8g.mongodb.net:27017 closed
    at Function.MongoError.create (C:\Users\558642\ga\js-dc-5\11-crud-and-dbs\assignment\todo\node_modules\mongodb-core\lib\error.js:29:11)
    at TLSSocket.<anonymous> (C:\Users\558642\ga\js-dc-5\11-crud-and-dbs\assignment\todo\node_modules\mongodb-core\lib\connection\connection.js:202:22)
    at Object.onceWrapper (events.js:293:19)
    at emitOne (events.js:101:20)
    at TLSSocket.emit (events.js:191:7)
    at _handle.close (net.js:511:12)
    at Socket.done (_tls_wrap.js:332:7)
    at Object.onceWrapper (events.js:293:19)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:191:7)
    at TCP._handle.close [as _onclose] (net.js:511:12)


Here's my code
const express = require('express')
const hbs = require('express-handlebars')
const mongoose = require('mongoose')
const bodyParser = require('body-parser')

mongoose.connect('mongodb://XXXXXXXXXXXX@isaaccluster-shard-00-00-yng8g.mongodb.net:27017,isaaccluster-shard-00-01-yng8g.mongodb.net:27017,isaaccluster-shard-00-02-yng8g.mongodb.net:27017/<DATABASE>?ssl=true&replicaSet=IsaacCluster-shard-0&authSource=admin')

const itemEntry = require('./models/toDoEntry.js')
const app = express()

app.get('/', function( req, res ) {
	itemEntry.find({}, function( err, itemEntries ) {
			res.render('todoList',

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0
Survive A High-Traffic Event with Percona
LVL 3
Survive A High-Traffic Event with Percona

Your application or website rely on your database to deliver information about products and services to your customers. You can’t afford to have your database lose performance, lose availability or become unresponsive – even for just a few minutes.

I am looking into Webpack 2 Code Splitting for a project but I'm not sure if I understand how code splitting works.

In my project I have 2 features.

Each feature consists of 4 or 5 files so the code for each feature has several javascript files where the code lives.

These javascript files are NOT ES6 Modules, just standard javascript files with code.

With Webpack 2 Code Splitting I intend to break all these files into 2 groups so that can load them on demand when needed.

So, what I'm thinking of doing with it is ...

1. Project Loads just the core

2. On demand the features will load when needed.

Would code splitting work in this circumstance and is this what it's for?
0
I am working on a project using, node, Webpack, babel and ES6.

Inside my project I've created a module which I want to load into the project at runtime.

The end result I'm looking for is that when the application will have different features. The code for each feature will be in a module.

The user can then enable or disable certain features at runtime.

How can I do this?
0
As a junior, I'm a bit new to front end programming (crammed learning JS/other languages/NPM/NodeJS/etc within three months for my current role) so apologies if what I say doesn't make sense.

I've helped to build a UI for an application with the use of NPM/Node JS. The application stores data on a UNIX server. The UI accesses the data on the server (https://myhostname:8090/blah/blah) and presents the results with a nice UI. With the help of GIT, I've managed to do move all the src UI code onto the UNIX server. The purpose is for automation

While a specific file (in my UI code) specifies the UNIX server configuration, I've used NPM to build a bundle.js (Which bundles all the JS files into a single file) file. I move this bundles.js along with the index.html and CSS styling files to an appropriate directory in order to use Maven to build a JAR file. And with a start/stop server script to run the process to run  the code, I can just enter the UNIX hostname/port number in my browser window in order to access the UI and data. This all works.

However. I now need to generalise the server configuration in my bundle.js file as well as properties file on server side such that I'm not hard coding server configuration anywhere (meaning I can deploy the UI on any server with no issue). i.e. playing with "localhost" instead of the actual server hostname etc.

I want to try my best, but I need to acknowledge that I have no real server configuration experience and hence need a …
0
Hi

In Facebook, 1000's of people can like or frown or comment on certain columns.

In the Facebook API, am I able to easily message those people interested in the topic? are there ways, Apps to do this? Any costs?

This message page suggests billions? Really . . . .? . . .  here

Do I need to use Java or PHP coding in any way?

Thanks
0
Hello Exchange Experts,

I have 1 DAG with 4 nodes with Exchange 2013, I would like to know if I could create 1 BD for my heath mailbox, I have read that is not a best practice to move them, but for my administration could be better. So my questions:
*  The health mailbox has to be local in each node? or I could have them all in one server
* Could I move the health mailbox to another DB, and another disk unit, in the same node?

Thanks a lot!
0
Hi All,

I have a 2 node hyper v cluster running a bunch of virtual machines.

I can successfully connect to the cluster via failover cluster manager with no issues. I have run the validate cluster tool which passes successfully also

When I right click on a node and select 'connect' I get the console window as expected, however it only works on hyper v host 1 not hyper v host 2.

When I also try and connect to the problem host via Hyper-V manager I receive the following:

Any suggestions?
Capture.PNG
Capture1.PNG
0

Node.js

Node.js® is a JavaScript runtime built on Chrome's V8 JavaScript engine. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient. Node.js' package ecosystem, npm, is the largest ecosystem of open source libraries in the world.

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