We Keep Coding

Fastest way to send data from C# to javascript? [closed]

Closed. This question is opinion-based. It is not currently accepting answers.
Want to improve this question? Update the question so it can be answered with facts and citations by editing this post.
Closed 1 year ago.
Improve this question
I have two separate apps. One of them is a UI web application written with pure JS, the other one is console application written by C#.
Currently I'm calculating some variables (which can not done in JS because of browser limitations) with C# console app, then it's writing results to a txt file.
Then I read the file with JS application to bring results to UI. But the variable often changes in milliseconds and writing results to disk and retrieving it again is pretty slow.
What can I do? Any suggestions?

The console application is effectively a server. Communicating between a web app and a server by means of a local text file is, well, unconventional! If this is not just for your own use on the one machine, it will be very difficult to deploy for another user. Write a small server application and communicate with it the usual way, i.e, by posting the data to the server's IP address and receiving the server's response. You can remove any connection latency (after the initial connection) by communicating over websocket.

As others pointed out WebSockets seem to be a great choice for this task.
Mozilla has a mini tutorial that seems perfect for this task: Writing a WebSocket server in C#.
RE: Comment:
Good point! There is also a MSFT guide for SignalR: Tutorial: Get started with ASP.NET Core SignalR

It's open to some debate what you mean by "fastest" - fastest for you to write or fastest in terms of performance of the app..
It's relatively simple to turn your C# code into an API - visual studio has templates for API type projects; your logic will then get a url and can be triggered simply by visiting it in any browser or having JavaScript do a fetch of the url. The url itself can be used to pass variable data, C# knows how to parse it and present it in code so a method like (attributes etc removed for clarity)
public class CalcController:ApiController{
public int Add(int a, int b){
return a+ b;
}
}
Can be triggered by visiting a url of `http://host/api/add/1/2 and you get JSON back, which JS understands out of the box. If your web app serves your js up the js can automatically talk to the web app without any CORS etc because it was served by the same server
See https://learn.microsoft.com/en-us/aspnet/core/tutorials/web-api-javascript?view=aspnetcore-5.0 for a full tutorial (it's pretty involved, uses databases and everything - you can boil it down a lot simpler, probably even just making a web app project from a SPA template in vs will create everything you need to have front end JS and back end C#
Another option to look at is Blazor; you can dump the JS entirely and put c# in the browser (or leave c# on the server and let Blazor handle transiting the UI changes between client and server) if you want, or you can interoperate with JS
Finally it's been commented about SignalR - a tech from MS that builds on top of websockets and handles the connectivity management, and finding and calling code on either end. It helps create event driven apps where the events happen at either end (like a chat app; one person speaks, it causes JS in their browser to call a method on the server and transits what they types to the server, then the server pushes that message out to a group of other connected clients). You set up events in your JS like "onChatReceived" so when the server pushes data, you respond to it. SignalR deals firewalls automatically; it either uses websockets (long lived bidirectional data flow), long polling (make a request and the server doesn't answer until a message it available to send) or repeated polling (any update? any update? any update?) automatically, so it can make your app very portable, especially if one day you want to host your calculations on a server you control, to protect you're intellectual property
Full MS tutorial on SignalR here - https://learn.microsoft.com/en-us/aspnet/core/tutorials/signalr?view=aspnetcore-5.0&tabs=visual-studio - you're essentially setting up a group of eventing mechanisms; your JS can trigger your server to do something and later your server can trigger your JS to do something.
This is slightly different to your JS requesting your server do something and waiting for the response - that model might work fine and be simpler for you to implement as its most close to what you already have, you're just swapping out the file reading for a network call, which JS is allowed to do autonomously

How to protect (obfuscate/DRM) trained model weights in Tensorflow.js?

I am working on a React-based web app that uses Tensorflow.js to run an AI model in realtime on the client in the browser. I've trained this AI model from scratch and I'd like to protect it from being intercepted and used in other projects. Are there any protections available to do this (obfuscation, DRM, etc.)?
From a business perspective, I'd only like the model to work on my web app, nowhere else.
The discussions (1 2 3) I've been able to find on this are more geared toward native apps, not web apps.
Here is an example open source web app that uses Tensorflow.js. These weights are an example of what I would like to protect in my app.

Client-side code obfuscation will never fully prevent it. Use a server instead.
Obfuscation
If your client-side application contains the model, then the user will be able to somehow extract it. You can make it harder for the user, but it will always be possible. Some techniques to make it harder are:
Obfuscating your code: That way the user will not be able to read your code and comments easily. Depending on your build tools, this might already be done for you when you produce a "production ready" build.
Obfuscating the library and its public API: Even if your code is obfuscated, the user might still be able to guess what is going on by seeing the public API calls of the library. Example: It would be rather easy to set a break point at the model.predict function and debug your code from there on. By also obfuscating libraries and their API, this will become harder.
Put "special checks" in your code: You could also check if the page the code is running on is your page (e.g. if the domain matches), etc. You also want to obfuscate this code as well.
Even if your code is perfectly obfuscated and well protected, your client-side code still contains your model somewhere. With these methods it will always be possible to somehow extract your model.
Server-side approach
To make it impossible to get your model, you need a different approach. Only put your "dumb logic" on the client. Exclude the part of code that you want to protect. Instead you offer a API on your server that executes the "protected part" of your code.
This way, instead of running model.predict on the client-side, you would make an AJAX request to your backend (with the parameters) and then return the results. That way the user only sees the input and the output and cannot extract the model itself.
Keep in mind that this means a lot more work, as you not only have to write the code for your client-side application but also for your server-side application, including the API. Depending on how your application looks like (e.g.: does it have a login?), this might be a lot more code.

Another way you can protect your model is to split the model into more than one blocks. Put some blocks at server side and some at client side. This method may also introduce a lot of engineering work, but once you do that you can trade off the computation loading and network latency between the server and client. Users can only get some model blocks which is useless without cooperating with server side blocks.

Is it safe to use AngularJS? [closed]

Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 7 years ago.
Improve this question
I've been developing my first AngularJS application for while, and I just realized that anyone could simply get/copy all the information from my JSON files at once. Therefore I ask:
Is is safe to use AngularJS - i.e. should I be worried about
people copying all the content of my app at once and then simply pasting
somewhere else?
Is there a way I can make it unreadable for people to read the JSON file? I do know that there are some tools and websites that could make Javascript scripts unreadable, but as I pass it to the view it makes the json unreadable by the browser.
There's a website called Udemy, that uses Angular in part of it. I have tried by all means to see the classes titlebut still I can't find/read the Json file that contains the content. How is such thing possible?
Many thanks.

You should never send to the user any data that they are not allowed read, independent from the fact whether the data is actually displayed on their screen. I assume that your data comes from a server (which possibly reads it from a DB); even with Angular.js you need to make sure that your server will only send the data that particular user is authorized to see.
So the answers to your questions are actually not related to Angular at all, but to the server-side technology you use to feed the data to the angular client running in the user's browser.

No, since AngularJS is client-side, anything you send it is available to the client. Therefore:
1) Depends on what you mean by safe. But yes, people can "read" all the content of your app that isn't in the backend.
2) No, not if you're using them in your javascript code.

There is no safe way to give someone both content and key but prevent them from read them.
And that is what DRM does, actually what you are looking for.
Actully, any content is not considered 'safe' after you sent both content and key to client.
If they have key and content, they of course can find some way to decrypt and read them.

First off, yes, it's safe to use AngularJs. Angular and any client-side utility should only be concerned with processing the "view logic" of the data it's receiving. That data is the result of the server-side "business logic" which is completely oblivious to the workings of Angular.
I believe you can still answer your security concerns by requiring authentication for your data. Require users to login and allow them to access data via an authentication cookie or similar model. You can get this out of the box (or at the very least learn the process) by using MEANJS (meanjs.org).
All JSON data supplied to your site should be the data you want to be seen. If you're concerned that people can simply use your JSON URLs to aggregate your data on their own servers (assuming they pass the authentication process) then I'm sorry to say there are plenty of tools and savvy developers who can cherry pick that data off any site regardless of whether it's delivered via JSON, HTML, XML, etc.
In order to reliably hide data between client and server you'll need to build your own web application (think app) that uses one or more encryption methods on both ends. Even if you try to build your own client-side encryption/decryption/two-way-handshake for a standard web browser, you'll inevitably expose the business logic nested in the Javascript and defeat the purpose entirely.

is json the answer to this: python program will talk and javascript will listen?

the same problem haunting me a month ago is still haunting me now. i know ive asked several questions regarding this on this site and i am truly sorry for that. your suggestions have all been excellent but the answer is still elusive. i now realize that this is a direct result of me not being able to phrase my question properly and for that i am sorry.
to give you guys a generalized view of things, here i go: the situation is like this, i have 2 server side scripts that i want to run.
a python program/script that continuously spouts some numbers
based on the output from that python script, a javascript script will perform some action on a webpage (e.g., change background color, display alert message, change some text)
ive studied the replies to my previous posts and have found that what i want to accomplish is more or less accomplished by json. it is my understanding that json transforms 'program-specific' variables into a format that is more 'standard or general or global'.
two different programs therefore now have the means to 'talk' with each other because they are now speaking the same 'language'.
the problem is then this, how do i actually facilitate their communication? what is the 'cellphone' between these server side scripts? do they even need one?
thank you!

If I understand what you're asking, the "cellphone" is TCP/IP. The javascript is not server-side; it runs on the client side, and alters what the client's browser displays based on json data that it downloads from the server -- data that in this case is generated by Python.
This question provides a relevant example, though it's a bit technical: JSON datetime between Python and JavaScript
Here's a very basic tutorial that explains how to create a dynamic webpage using python and javascript. It doesn't appear to use json, but it should familiarize you with the fundamentals. Once you understand what's there, using json to transport more complicated data should be fairly straightforward.
http://kooneiform.wordpress.com/2010/02/28/python-and-ajax-for-beginners-with-webpy-and-jquery/

I assume you mean: Python is on the web server, and Javascript is running in the client's web browser.
Because browsers are all different (IE6 is terrible, Chrome is great), there are a huge number of ways people found to "hack" this "cellphone" into place. These techniques are called AJAX and COMET techniques. There is no one "cellphone", but a whole bunch of them! Hopefully, you can find a library to select the right technique for the browser, and you just have to worry about the messages.
Comet is harder to do, but lets the server "push" messages to the client.
Ajax can be easier - you just periodically "pull" messages from the server.
Start with Ajax, then look at comet if you really need it. Just start by have the client (javascript) make a "GET" request, to see if the number has changed.

I don't know Javascript or json, but...
if you've ever seen an Unix-like operating system, you know about pipes. Like program1 | program2 | program3 ... Why don't you just connect Python and Javascript programs with pipes? The first one writes to stdout, and the next one reads from stdin.

This probably isn't the answer that you are looking for, and without links to your previous posts, I don't have much to go on, but nonetheless...
javascript is client side. I can interpret your question 2 different ways...
Your python script is running on your computer, and you want a script to actually alter your current browser window.
Not too sure, but writing a browser plugin may be the answer here.
Your python script is running on the server, and as a result of the script running, you want the display of your site to be changed for viewing persons.
In this case, you will could use ajax polling (or similar) on your site. Have your site be polling the server with ajax, call a server method that checks the output of the script (maybe written to a file?), and see if it has changed.

When 2 process need to communicate, they need to decide of a common/shared way to express things and a protocol to exchange those things.
In your case, since one of the processes is a browser, the protocol of choice is http. So the browser needs to do an http request or regular http request to your python process.
This python process Will need in Some way or another to be exposed via http.
There are several ways to build a web server in python. You should read this article : http://fragments.turtlemeat.com/pythonwebserver.php as a jumpstart.
Once you have this, your browser Will be able to issue HTTP GET requests to your server and your server can reply with a string.
This string can be whatever you like. Nevertheless if your answer contains structured data it can be a good start to use the XML notation or the json notation.
Json (stands for Javascript object notation) is very easy to use in javascript and this is why many people advised you to choose this notation.
I hope this will help you
Jérome wagner

Do I need server-end knowledge (e.g. Django, Rails), if I want to do Javascript, AJAX stuff?

I am trying to get into web development, specially interested building the front-end, UI part of websites while learning JavaScript maybe with AJAX technology. (I have a UI, HCI background.)
However, I have absolutely no previous knowledge about server-end web development either. To my understanding, frameworks like Django seem to pretty good at this (correct me if I am misunderstanding).
So the question is: how much Django, or Rails do I need to know, if my interest is primarily the user interface part of web development. Can I just let somebody else do the back-end stuff?
Pardon me for my imprecise choice of terminologies.

You need to know a bit about the server side. Here's what you need to know.
If you have a heavy JavaScript website, you're likely going to want to pass information from the server to clients with JSON (JavaScript Object Notation). This is just a way to format data into strings that JavaScript knows how to convert to objects.
So, each of your server-side functions that send data to the client will return JSON. If you have someone writing the server-side for you, that's all you should have to know. You're JS functions will receive JSON, and then you deal with it.
If you have to write the server-side yourself, then that involves 1) getting data from database 2) formatting the data 3) converting to JSON.
I have open-sourced a commenting widget that accepts JSON messages, and gives examples of how you would set up the Django server code. Maybe it will help you: http://www.trailbehind.com/comment_widget/

You can make a career of front-end user interface development without know a ton about server code. You would do well though to have at least a rudimentary understanding of what happens on the server when you send it a request, where your data comes from, and what the life-cycle of a web page is. This assumes that you have the support of back-end developers. As you mentioned Ajax in your question that implies that you want your web sites to actually do something, which will require things to happen on the back-end (such as storage, manipulation of data, logging in a user, etc.).
As with all things, the more you know, the easier it will be to get what you want from the dedicated professionals. I would suggest that you learn about programming in general, not try an learn a language and framework. In particular, try to understand datatypes, server settings (like timeouts, post versus get, etc.), security and database interactions as they exist beyond JavaScript/ECMAScript. That way when a developer is explaining why they cannot do something you have requested or are offering alternatives, you are speaking the same language.

Yes and no. Typically what people think of AJAX, such as posting a comment on YouTube and seeing the comment appear instantly with a thank you message, for example, requires a server side language handling the requests, looking up data and returning results as html snippets, JSON data, or XML.
However, an AJAX call can be made to static resources as well. You could have an XML file or html snippet stored statically on your web server and have it loaded. The uses for this sort of static loading are generally fewer because if you already have the static html or data in file next to your regular page, why not just put that data directly into the page?

It helps to set up a local server and write a few lines of code to service your AJAX calls. You can do a lot of JavaScript learning with just a little back-end learning.

If you're new in web development you'd rather wait with Ajax and server-side languages until you've learnt the basics with HTML, CSS and JavaScript, especially if you want to mostly work with the user interface and not the funcionality.

As you said you can let somebody else do the back-end and focus on front-end (JavaScript, HTML, CSS).
You would need to communicate with the back-end developer when storing or processing data from the server.
As mentioned before back-end development knowledge would be useful but if you have someone doing it, it's not essential for beginning.