I'm currently working on a web based educational tool where student can look at example of code in a browser and edit the code in the browser. I have been trying to implement a system where by they can interface with a client-side compiler and run/debug the code with in the browser. The more research I do the more I see that browsers are designed against letting this happen because of the security issues that this creates. I was wondering is there any way to run a compiler locally i.e via a extension or ajax or some other method.
The aim is to accommodate as many languages as possible although we are starting of with python.
I'm aware that I could run the script server side and display the output however This is limited in application(to my knowledge), Specifically regarding to GUIs.
I needed to do something like this (though not a compiler) for a project of mine. It had to download and process a resource given its URL into a format that could be read on a kindle. It's not exactly similar to yours since I had a browser plugin (rather than a web page) which triggered the operation and even that was not allowed to "leave" the browser.
In the end, I was forced to write a little app that ran on the client side which the plugin submitted the URL to and then processed.
The setup is something like this
browser plugin (via ajax) <------> web app on client ----> compiler/etc.
The browser sends the code snippet (in your case, a URL in mine) to a web app that runs on the local machine listening on some port (say 9999). It can access local resources and so can actually run the code and then return something to the browser which can then render it.
In my case, the browser sends a JSON string to the web app which just contains a URL. The web app fetches the resource, processes it and converts it into a .mobi file which the kindle can read and then drops it into a directory. The result of the conversion (success/failure) and the location of the converted file is sent back to the browser which informs you that it's done.
I don't think you can write a plugin that directly accesses the compiler. It'll have to communicate with a local app. The setup is complicated for non technical users (look at the README on my project) but it works.
Related
I'm trying to get some tables with specific filters on this qlikview page, for future analysis: http://transferenciasabertas.planejamento.gov.br/QvAJAXZfc/opendoc.htm?document=painelcidadao.qvw&lang=en-US&host=QVS%40srvbsaiasprd01&anonymous=true
I don't want to do it manually (downloading tables for every filter). Therefore, I searched for API's for Python on qlikview website, but only found qliksense API's for SSE (like this https://github.com/qlik-oss/server-side-extension).
Is there any chance that I could automate the retrieving process that I explained using Python?
Server side extensions are used for something else. They extend Qlik's functionality to process data (for example running some statistical functions on top of the displayed data if such functions do not exists in Qlik natively)
Interestingly is that the portal link (http://transferenciasabertas.planejamento.gov.br) is a QlikView app that later redirects to a Qlik Sense app(s). It seems that anonymous users are allowed on the platform (which makes automating data retrieval easier).
Qlik Sense communicates with the browser via web sockets. So the answer to your question is - yes. You can used Python to connect to the underlying Qlik Sense Engine and make some selections and get the data back.
The not very good news is that I dont think there is dedicated Python library so you'll have to send the raw web socket requests by yourself. The documentation for the Engine API can be found at Qlik's help site
If you are open for JS solution then you can use Qlik's enigma.js library for Engine communication.
The web sockets traffic can be monitored from the browser (to view what data is being send/received and its format)
Actual situation:
The client downloads a small pythonscript that is executable.
The client executes it. The script gathers information from the computer and sends the data to the webserver vià POST-Method.
Wanted Situation:
After the webserver recived the data, it should forward the information to the website-session of the client. And the website should display the information.
This is a visual example of the principle:
There is also a example of this principle on Can You Run It.
How can I realize this?
A common way of implementing this is using a RESTful API. Basically the API does not care if the request is from a script or web browser, it just passes data structures to and from clients. The only tricky part to your example is when there are multiple users involved because a secret must be shared between the browser and script. I believe Can You Run It puts this unique secret into the program they ask you to download.
Look into Django Rest Framework for examples of how to implement this.
I'll briefly explain what I'm trying to achieve: We have a lot of servers behind ipvsadm VIPs (LVS load balancing) and we regularly move servers in/out of VIPs manually. To reduce risk (junior ops make mistakes...) I'd like to abstract it to a web interface.
I have a Python daemon which repeatedly runs "ipvsadm -l" to get a list of servers and statistics, then creates JSON from this output. What I'd now like to do is server this JSON, and have a web interface that can pass commands. For example, selecting a server in a web UI and pressing remove triggers an ipvsadm -d <server>... command. I'd also like the web UI to update every 10 seconds or so with the statistics from the list command.
My current Python daemon just outputs to a file. Should I somehow have this daemon also be a web server and serve its file and accept POST requests with command identifiers/arguments? Or a second daemon for the web UI? My only front end experience is with basic Bootstrap and jQuery usually backed by Laravel, so I'm not sure if there's a better way of doing this with sockets and some fancy JS modern-ism.
If there is a more appropriate place for this post, please move it if possible or let me know where to re-post.
You don't need fancy js application. To take the path of least resistance, I would create some extra application - if you like python, I recommend flask for this job. If you prefer php, then how about slim?
In your web application, if you want to make it fast and easy, you can even implement ajax mechanism fetching results based on interval to refresh servers' data every 10 seconds. You will fetch it from json served by independent, already existing deamon.
Running commands clicked on Web UI can be done by your web application.
Your web application is something extra and I find it nice to be separated from deamon which fetch data about servers and save it as json. Anytime you can turn off the page, but all statistics will be still fetching and available for console users in json format.
I'm looking for a bit of web development advice. I'm fairly new to the area but I'm sure there are some gurus out there willing to part with some wisdom.
Objective: I'm interested in controlling a Python application on my computer from my personal web hosted site. I know, this question has been asked several times before but in each case the requirements were a bit different from my own. To reduce the length of this post I'll summarize my objective in a few bullet points:
Personal site is hosted by a web hosting company
Site uses HTML, PHP, MySQL, Python and JavaScript, the majority of everything is coded by me from the ground up
An application that is coded in Python will run on a PC within my home and will communicate with an Arduino board
The app will receive commands from the internet to control actuation via the Arduino, and will transmit sensor data back to the site (such as temperature)
Looking for the communication to be bi-directional, fast and secure
Securing the connection between site and Python app would be most ideal
I'm not looking to connect to the Python application directly, the web server must serve as the 'middle man'
So far I've considered HTTP Post and HTML forms, using sockets (Python app would run as a web server), an IRC bot and reading/writing to a text file stored on the web server.
I was also hoping to have a way to communicate with the Python app without needing to refresh the webpage, perhaps using AJAX or JavaScipt? Maybe with Flash?
Is there something I'm not considering? I feel like I'm missing something. Thanks in advance for the advice!
Just thinking out loud for how I would start out with this. First, regarding the website itself, you can just use what's easiest to you, or to the environment you're in. For example, a basic PHP page will do just fine, but if you can get a site running in Python as well, I'd prefer using the same language all over.
That said, I'm not sure why you would need to use a hosted website? Given that you're already forced to have a externally accessible PC at home for the communication, why not run a webserver on that directly (Apache, Nginx, or even something like CherryPy should do)? That webserver can then communicate with the python process that is running to control your Arduino (by using e.g. Python's xmlrpclib). If you would run things via the hosting company, you would still need some process that can handle external requests securely... something a webserver is quite good at. Just running it yourself gives you all the freedom you want, and simplifies things by lessening the number of components in your solution.
The updates on your site I'd keep quite basic: commands you want to run can be handled in the request handlers of the webserver by just calling the relevant (xmlrpclib) calls. Dynamically updating the page is best done by some AJAX calls I reckon. Based on your story, these updates are easily put in a JSON object, suitable for periodically updating only the relevant segments of your page.
Is it possible for my python web app to provide an option the for user to automatically send jobs to the locally connected printer? Or will the user always have to use the browser to manually print out everything.
If your Python webapp is running inside a browser on the client machine, I don't see any other way than manually for the user.
Some workarounds you might want to investigate:
if you web app is installed on the client machine, you will be able to connect directly to the printer, as you have access to the underlying OS system.
you could potentially create a plugin that can be installed on the browser that does this for him, but I have no clue as how this works technically.
what is it that you want to print ? You could generate a pdf that contains everything that the user needs to print, in one go ?
You can serve to the user's browser a webpage that includes the necessary Javascript code to perform the printing if the user clicks to request it, as shown for example here (a pretty dated article, but the key idea of using Javascript to call window.print has not changed, and the article has some useful suggestions, e.g. on making a printer-friendly page; you can locate lots of other articles mentioning window.print with a web search, if you wish).
Calling window.print (from the Javascript part of the page that your Python server-side code will serve) will actually (in all browsers/OSs I know) bring up a print dialog, so the user gets system-appropriate options (picking a printer if he has several, maybe saving as PDF instead of doing an actual print if his system supports that, etc, etc).