Working with Node.JS - node.js

Last night I dump windows 7 and formatted my hard driver to port to a Linux based operating system, Purely for the reasons that I wanted to start working with Node.JS
So I have installed Node.JS and have done a few test stuff, the http server and sockets etc.
What I would like to do is build a HTTP Server that is tightly intergrated with an MVC Framework, but before I get started on all that I need to learn how to build efficiently in Node.
For example within PHP as my framework I would create a bootloading system to load all base classes etc, then i would fire my events system ready to start attaching callbacks.
I would continue to process the request etc until the output is generated which then gets sent of to an output handler that would process headers etc etc
But Node s a totally new environment for this and im wondering on the best practises to build an system in Node.
The information im looking for is more to do with the design structure rather then the actual coding of the application, how to load the lib where to load the libs, etc etc
Any help is appreciated.
So far my WebApplication is coming along nicely, I have built my application pretty traditionally and a little procedural.
What i have started out is creating a directory structure like so:
<root>
startup.js
/public/
favicon.ico
/images/
/stylesheets/
/javascripts/
/system/
init.js
config.js
/libs/
/exceptions/
http.js
server.js
/application/
/views/
/_override/
/errors/
generic.view
/partials/
sidebar.voew
index.view
/controllers/
index.js
/models/
users.js
This directory structure is like most MVC Based Web Applications out there so using this method I feel comfortable.
The startup file is whats executed by node as the entry point, node startup & and looks like so:
/*
* Header of t he file, Copyright etc
*/
var _Intitialize = require("./system/init.js");
//Displays the command line header, title, copyright etc
_Intitialize.DisplayCommandLineHeader();
//Check the enviroment, Permissions, Ports etc
_Intitialize.CheckEnviroment();
//Start the server and listen the port.
_Initialize.StartServer();
the init file is the main work, its what tells all other areas of the system to run, stop etc.
I have a file in libs called serverhandler.js, and this is required into init.js, I then create a server and assign the callback to the ServerHandler.Listener. Who then listens for requests, checks to see if the file exists in public directory, if so it then reads in chunks and sends back.
if no file was found in public it would then create a route with Route.Create("/path?params"); which deters 3 elements, Controller, Method, Params from the uri, and then the controller files are loaded if exists.
I've taken on the approach of throwing error pages like so:
if(!FileSystem.exists(RequiredPath))
{
throw new HTTPExceptions.FileNotFound();
}
Hope this helps some people getting started in Node.

Have a look at
http://dailyjs.com/2010/11/01/node-tutorial/ , it's pretty relevant.
I would suggest looking at the current modules too
https://github.com/joyent/node/wiki/modules
and reading the code of any of the projects in the areas you are interested in, esp. the middleware, routing and module loaders.

Related

AppImage from electron-builder with file system not working

I’m using Electron Builder to compile my Electron app to an .AppImage file, and I’m using the fs module to write to an .json file, but it’s not working in the appimage format (it’s working fine when I have the normal version not made with Electron Builder). I can still read from the file.
The code (preload):
setSettings: (value) => {fs.writeFileSync(path.join(__dirname, "settings.json"), JSON.stringify(value), "utf8")}
The code (on the website):
api.setSettings(settings);
The project: https://github.com/Nils75owo/crazyshit
That's not a problem with AppImage or Electron Builder but with the way you're packaging your app. Since you didn't post your package.json*, I can only guess what's wrong, but probably you haven't changed Electron Builder's default behaviour regarding packing your application.
By default, Electron Builder compiles your application, including all resources, into a single archive file in the ASAR format (think of it like the TAR format). Electron includes a patched version of the fs module to be able to read from the ASAR file, but writing to it is obviously not supported.
You have two options to mitigate this problem: Either you store your settings somewhere in the user's directory (which is the way I'd go, see below) or you refrain from packing your application to an ASAR file, but that will leave all your JavaScript code outside the executable in a simple folder. (Note that ASAR is not capable of keeping your code confidential, because there are applications which can extract such archives, but it makes it at least a little harder for attackers or curious eyes to get a copy of your code.)
To disable packing to ASAR, simply tell Electron Builder that you don't want it to compile an archive. Thus, in your package.json, include the following:
{
// ... other options
"build": {
// ... other build options
"asar": false
}
}
However, as I mentioned above, it's probably wiser to store settings in a common place where advanced users can actually find (and probably edit, mostly for troubleshooting) them. On Linux, one such folder would be ~/.config, where you could create a subdirectory for your application.
To get the specific application data path on a cross-platform basis, you can query Electron's app module from within the main process. You can do so like this:
const { app } = require ("electron"),
path = require ("path");
var configPath;
try {
configPath = path.join (app.getPath ("appData"), "your-app-name");
} catch (error) {
console.error (error);
app.quit ();
}
If you however have correctly set your application's name (by using app.setName ("...");), you can instead simply use app.getPath ("userData"); and omit the path joining. Take a look at the documentation!
For my Electron Applications, I typically choose to store settings in a common hidden directory (one example for a name could be the brand under which you plan to market the application) in the user's home directory and I then have separate directories for each application. But how you organise this is up to you completely.
* For the future, please refrain from directing us to a GitHub repository and instead include all information (and code is information too) needed to replicate/understand your problem in your question. That'd save us a lot of time and could potentially get you answers faster. Thanks!

GET / POST using Clarion

I have Clarion 9 app that I want to be able to communicate with HTTP servers. I come from PHP background. I have 0 idea on what to do.
What I wish to be able to do:
Parse JSON data and convert QUEUE data to JSON [Done]
Have a global variable like 'baseURL' that points to e.g. http://localhost.com [Done]
Call functions such apiConnection.get('/users') would return me the contents of the page. [I'm stuck here]
apiConnection.post('/users', myQueueData) would POST myQueueData contents.
I tried using winhttp.dll by reading it from LibMaker but it didn't read it. Instead, I'm now using wininet.dll which LibMaker successfully created a .lib file for it.
I'm currently using the PROTOTYPE procedures from this code on GitHub https://gist.github.com/ddur/34033ed1392cdce1253c
What I did was include them like:
SimpleApi.clw
PROGRAM
INCLUDE('winInet.equ')
ApiLog QUEUE, PRE(log)
LogTitle STRING(10)
LogMessage STRING(50)
END
MAP
INCLUDE('winInetMap.clw')
END
INCLUDE('equates.clw'),ONCE
INCLUDE('DreamyConnection.inc'),ONCE
ApiConnection DreamyConnection
CODE
IF DreamyConnection.initiateConnection('http://localhost')
ELSE
log:LogTitle = 'Info'
log:LogMessage = 'Failed'
ADD(apiLog)
END
But the buffer that winInet's that uses always returns 0.
I have created a GitHub repository https://github.com/spacemudd/clarion-api with all the code to look at.
I'm really lost in this because I can't find proper documentation of Clarion.
I do not want a paid solution.
It kind of depends which version of Clarion you have.
Starting around v9 they added ClaRunExt which provides this kind of functionality via .NET Interop.
From the help:
Use HTTP or HTTPS to download web pages, or any other type of file. You can also post form data to web servers. Very easy way to send HTTP web requests (and receive responses) to Web Servers, REST Web Services, or standard Web Services, with the most commonly used HTTP verbs; POST, GET, PUT, and DELETE.
Otherwise, search the LibSrc\ directory for "http" and you will get an idea of what is already there. abapi.inc for example, appears to provide a wrapper around wininet.lib.

Why can't I require files which are available due to app.use?

If a directory has been made available to a node application in the server.js file which sits in the main directory using:
app.use("/scripts",express.static(__dirname + "/scripts"));
and I attempt to use require from a file inside of that directory (/scripts/custom.js) using:
var Testing123 = require('../app/models/article');
Is there a reason this is not possible? and is there a solution to that problem?
Edit: In one of my views (views/tree.ejs) I use:
<script type="text/javascript" src="../scripts/custom.js"></script>
to access my Custom script which sits inside my scripts folder which is made available using express.static, Custom uses a web scraper to scrape articles and present them in circles (in the form of an image, title and link) on views/tree.ejs, I now want custom.js to save each article it creates to a mongodb database but to do so, it needs access to things like my Article Schema hence the problem above.
You cannot because Node.js scripts and browser scripts do not run in the same context. Your app.use call just exposes a /scripts route that serves assets statically on your HTTP Server.
Your scripts/custom.js script seems to be a browser-side script (Because you load it with a script tag inside an ejs view) but you want to use require inside it and this will not work as this is a Node.js function.
Have a look at LearnYouNode which is an excellent Node beginner tutorial so that you will understand how modules work in Node and know a bit more about the separation between server-side and client-side JS.

Change configuration in runtime by changing environment variables using the module node-config

I'm trying to use the node-config module to change some parameters of my configuration (basically logging level) during runtime.
In the official documentation says:
Environment variables can be used to override file configurations. Any environment variable that starts with $CONFIG_ is set into the CONFIG object.
I've checked that this is true when the server starts but it does not seem to work once it's up. (The handler of the watch function is never called when an environment variable is changed unlike a change in the runtime.json file or directly changing a config variable).
I'm currently watching the whole CONFIG object like this:
var CONFIG = require('config');
CONFIG.watch( CONFIG , null , function(object, propertyName, priorValue, newValue){
console.log("Configuration change detected");
});
Does anyone know if this is possible?
The environment is available during startup of a process.
If the process is running, you won't be able to change the environment anymore, the process is in.
The only option is to restart the process or use other mechanisms to communicate with it.
Say for example having a rest or tcp listener inside, where you can transfer your variable inside.
Best regards
Robert
As you must knowing, React is a single page application which is eventually when it is complied is a static page app that means all the files of the react application is complied into vanilla JS and CSS file bundle in a Tarball. Now that Tarball is eventually deployed on a web server. It could be Apache web server, nginx web server or anything which you are using it but an important point is the static app is running in someone else browser and someone access to website CSS and JS are downloaded in a browser and it is running in the browser runtime environment so technically you cannot have a runtime environment variable for someone else browser but may be there would be a way to access them during runtime.
SOLUTION
I have achieved this goal with the package called runtime-cra.
follow the steps on this official documentation: https://blog.risingstack.com/create-react-app-runtime-env-cra/

Temporary File Download

Is there a service that creates basically a one-time download of a file, preferably something I can use from NodeJS?
I've done some research on FilePicker, and haven't found anything about regenerating the link it gives you for a file. There may be a way to do this with NodeJS, but I'm using Meteor at the same time so many Node things probably will conflict.
You could build it with meteor. Using meteor-router with meteorite & use server side routing to deliver the files.
You need a collection to keep track of downloaded files:
Server JS
var downloads = new Meteor.Collection("downloads");
//create a link
downloads.insert({url:"/mydownload.zip",downloaded:false})
Meteor.Router.add('/file/:id', 'GET', function(id) {
download = downloads.findOne(id);
if( download) {
if(dowload.downloaded) {
this.response.send("You've already downloaded me")
}
else
{
//I guess you could just redirect or stream the file for an extra layer of surety
this.response.redirect(download.url);
}
}
});
On the client you can use /files/{{_id}} with _id of the file from downloads the person has as the link
My recommendation would also be to add custom server-side logic to count # of uploads (or just flag a file as downloaded/not downloaded) and respond accordingly. The closest you could do with Filepicker.io would be using the security policies to restrict downloading the file to a specific time interval.
in addition to using the router package
in Meteor.startup you can add
var require = __meteor_bootstrap__.require;
fs = require( 'fs' );
the fs variable should be declared on the server only. the fs package is used by Meteor and does not need to be added separately.
once you have done this, you can create files with Meteor.uuid() as their name which makes them unique and very difficult to guess. It is also possible to delete the file after a certain amount of time by using Meteor.setTimeout
the question is: where do the files to be downloaded come from?
Solution using Heroku Cloud and NodeJS Meteor Hooks
Heroku in particular is actually great for temporary file download links: they offer a "temporary scratchpad" filesystem that is reset every time the program restarts, and each running Node server cannot see the files other instances have created.
Each dyno gets its own ephemeral filesystem, with a fresh copy of the
most recently deployed code. During the dyno’s lifetime its running
processes can use the filesystem as a temporary scratchpad, but no
files that are written are visible to processes in any other dyno and
any files written will be discarded the moment the dyno is stopped or
restarted.
Taken from the Heroku documentation: https://devcenter.heroku.com/articles/dynos#ephemeral-filesystem
Thus, any files written to the "filesystem" will be temporary.
This allows for a very easy solution to this problem: you can simply use NodeJS filesystem manipulation to create temporary files on the server, serve them once (or for a limited time), and then remove them so they cannot be downloaded again.
This in combination with something like $.download() will make a seamless experience which in turn prevents unauthorized downloads.

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