How to create web application using Qt?
This depends on what you mean by "web application". If you mean an application that can show parts of a web page in its interface as rendered HTML, like a browser can...yes. Qt incorporates something called QtWebKit:
http://doc.qt.io/qt-5/qtwebkit-index.html
(Note: Back in the olden days it was Microsoft--I think--who first made an embeddable Internet Explorer control so that you could fetch a URL into the midst of some MFC or VB application and run a browser in the midst of your otherwise-form-based application. The event hooks for Microsoft's solution sucked, Qt's are much better.)
Anyway, this is great if you want people to install your application on their machine, where it fetches web data but takes advantages of native features to be richer than a browser could. But be careful because these days native apps have to be really outstanding to surpass the advantage of something that runs in a browser they already have.
HOWEVER If you are trying to use QtCore to push server-side content out and fulfill web requests, that'll be an uphill battle. You might find some related examples if you look hard enough:
https://web.archive.org/web/20100922075100/http://labs.qt.nokia.com/2006/12/20/whats-this-cgi/
Very few people use C++ (much less Qt) to generate web pages server-side. Yet there are still some doing it, even in pretty cool ways:
http://www.webtoolkit.eu/wt
...regardless, QtCreator will be no help in that kind of pursuit.
The functionality you are asking for does not exist within Qt itself. However, there exists (at least) one third party library that allows some of the Qt code for a desktop app to be re-used to a certain extent for serving up a web app:
http://cutelyst.org/
However, this does not magically allow you to write a QML interface with QML Widgets and have a visual interface accessible via a web browser.
What do you mean by "web application"? Is it a desktop app with web features? If so, yes Qt in general is very good for that.
If you mean a kind of server that outputs HTML, then you should use something else because you would have to reinvent many wheels to make it work.
You'd require to run or embed web server. It would be more whise to turn to a Apache Web Server or Apache Tomcat based approach. Otherwhise you'd run somewhat against the odds.
Consider also using some HTTP server library like libonion or Wt. Wt is close in spirit to Qt. However, you won't use Qt itself. libonion is lower level (and you may want to use browser-side Web frameworks like e.g. JQuery or AngularJS with it).
If you already have some Web server, you could consider developing some FastCGI application in C++.
You surely need a good understanding of HTTP protocol and of HTML5 & AJAX.
Since this is 11 years old, I thought I'd come here to tell you that it does indeed seem possible now that qt supports webassembly. The newest version, 6.4 (newest version as of today jan 31 2023), now offers support for webassembly and their website has various examples of apps built with qt that run in the browser.
https://www.qt.io/qt-examples-for-webassembly
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I'm using Python and QT (PySide) in a local application (which connect to a database on cloud Azure).
Now, my objective is moving this app on the web, in particular on Azure (I have an Azure subscription), simply transfering it on Azure, it's possible in some manner? I have not found examples on the web.
The important question is: is Python QT (app web) compatible with Azure?
Thanks
UPDATED ANSWER!
Yes, now you can. Well sort of. The mad mads at Digia have created something called "QT for Web Assembly" that can compile your whole app into something that runs embedded into a web page.
https://doc.qt.io/qtcreator/creator-setup-webassembly.html
You might have to rethink connecting directly to the database however, as thats simply not gonna fly with web-sockets (And honestly direct app to remote RDBMS has never been a smart move. Theres a LOT of things that can go wrong letting the internet connnect to your databaes). But you could at least keep the UI and rewrite the databaes layer to interogate something like a GraphQL (or whatever) front end to the data.
OLD ANSWER
I'm afraid your up for a nearly complete rewrite. QT is a desktop/mobile platform. It doesn't go anywhere near HTML/CSS except perhaps for displaying them in a webview component. Azure or AWS won't magically make it into a web application for you.
Your code as it stands needd to be rewritten in a web-first transactional manner. That is it takes a request, processes it, produces a result. To some extent websockets has changed this dynamic for a limited subset of use cases where interaction needs to be non transactional, and modern web app design hides much of the transactionality behind a web-services model, but 90% of web work is still very much transactional.
Database <---> Web server/Web app stack <--- Internet! --> Web browser
My suggestion is to pick up Django (or one of the other systems. If its just simple, Flask is another good alternative. Flask for simple apps, Django for the big stuff. Or use something else, you have choices here!, and start from scratch. Analyse your products function and start mapping out how to make this work as a database driven transactional system.
Theres no shortcuts here, I'm afraid.
I'm looking at enterprise JavaFX, and how to integrate JavaFX with server-side code. In the last few weeks I've done a certain amount of research in DataFX and Open Dolphin, and downloaded some videos, as well as looking at a couple of other frameworks. For example I've looked at the video on DataFX at:
https://www.youtube.com/watch?v=EN4fo6x0DcQ
However, although this video and others I've looked at explain how to set up a client application that connects with a server, I've found very little information on how to put together some server-side code that the client can connect to. Sure, one could use JAX-RS, but why re-invent the wheel? In the first instance I would like to put together some really simple server-side code that some test client-side code can connect to using DataFX or one of the other frameworks. The aim eventually is to get a client using JavaFX to communicate with a server.
My second question is that of the various frameworks available, is DataFX the best to use for a simple application?
I have experience with a Glassfish server hosting a JSF application, and it may be useful to have such a server hosting a JSF application communicating with a browser as well as communicating with a client JavaFX, as that way I can test out that the communication with the JavaFX application.
The latter is a bit of an aside, and my main questions are where can I get information on server-side programming for this, and the best frameworks to use?
Many thanks in advance.
If you are able to manage yourself the client-server communication you can pick any JavaFX Application Framework listed there:
https://github.com/mhrimaz/AwesomeJavaFX
Any of them allows to separate UI code from communication code.
As I'm author of JRebirth, I can advice you to create some RemoteService (extends Service and providing JAX-RS facilities or whatever) to perform this job.
If you search an all-in-one library managing client AND server side, DataFX + OpenDolphin is probably the most advanced one.
I'm the author of DataFX & Dolphin Platform (https://github.com/canoo/dolphin-platform). Both are valid frameworks that fill fit to your needs. Maybe a combination of both - Dolphin Platform as remoting layer between client and server and DataFX to define the routing and mvc based views on the client.
Some days ago I copied all the DataFX sources to GitHub (https://github.com/guigarage/DataFX) and currently trying to create a new version based on the modules that are maintained by me. Maybe I will extract the MVC related stuff and create a new framework based in it, we will see. What I currently can say is that I plan to work on it the next month next to the Dolphin Platform since I think a combination of both will be a good fit.
I would use this combination today to create applications but yeah, I'm the main developer of both frameworks so the choice is quite easy for me ;)
As you mentioned JSF I think that Dolphin Platform is a perfect match for you since one idea of the framework is to have a modern successor for JSF that can be used to create desktop & web based applications but provide managed controllers on the server. We provide a cool maven based jumpstart (Maven archetype) that will give you a quick introduction and a runnable client / server application with a desktop and web client in 2 minutes: https://canoo.github.io/dolphin-platform/#_dolphin_platform_jumpstart
I have a qt main-window application from which several dialogs are accessed.
I implemented the server and client versions of the application using tcp/ip using c socket programming.
But now I have been told to make the application accessible to any web browser after username and password have been given using QHttp or any appropriate class.
I'm a beginner and have no idea of implementing this. Could anyone give some tips or examples.
I'm using qt 4.6.2
I'm not sure I understand you. You have a Qt main window which contains some widgets arranged in a GUI. You want those same widgets to be accessible inside a web browser? Then you need to re-create all your GUI code in HTML, CSS and JS.
Your Qt app can use QHttp to listen for incoming client connections. When one of those comes, you reply with a webpage (written in HTML, CSS, JS). When this webpage is received by the user, his browser will display it. When the user interacts with the webpage, you'll probably want to send some data back to the Qt server eventually. You can do this either via form posting or via XMLHttpRequest.
You should know client-side web development is not that simple. Even when you know your languages, there's lots of things to learn about browser compatibility, security, accessiblity, JS app architecture, etc.
You want to make your application into an Http server. Here is an example using Qt to get you started:
http://doc.qt.nokia.com/solutions/4/qtservice/qtservice-example-server.html
As Stefan notes, this means putting your GUI into HTML/CSS/JS and more.
Over the past 6 months I've been developing web sites using asp.net. When I design something such as a contact form, 99% of the time I find myself using a script manager and update panels. Recently I tried out silverlight and expression blend, and I love it.
Is there any big cons for me to start building my forms with silverlight instead? The only big one I can think of is the user might not have silverlight and not want to download the plugin.
I guess to solve the has and has not issue, I could make a silverlight version and a standard version until it comes to the point where the plugin is as popular as flash.
Personally i would advocate doing everything in SL because i love what you can do with it. But common sense dictates otherwise. There is no point replacing relatively static webpages with a SL app. While there are methods to communicate/cooperate between SL apps and the web pages that host them, you don't really want to do this unless you have to, you can end up with quite a kludgy solution.
SL is not suitable for everything. The times you want to use it are when you can redo (or create) a whole web app (or significant chunks of it), and you want to create a more immersive and interactive desktop-like experience for the user. You also need to read up on authentication with SL and WCF services, SL navigation, and become familiar with the SL4 Out of Browser feature as it offers you some features/benefits beyond what is available to an in-broswer SL app.
The Silverlight plugin is not available in mobile devices. Also, SL 3/4 is not yet 100% supported in Linux.
You really have to take in consideration your targeted audience.
If your app is meant to be used anywhere SL or event Flash is not a good choice. None of them run on iPhones for instance.
The Silverlight platform is a good compromise between the richness of a fat client and the easy of deployment of a web app. Intranet environmentss are great candidates to take advantage of that.
The platform runs well in both Windows and Macs, and should get better in Linux too.
We have a large code base in MFC and VB. A few applications are in .NET. All these applications interoperate with each other on the user's machine and also connect with Unix servers via sockets.
Recently we have started discussing a re-write of our applications and possibility of moving a lot of these desktop applications to web (they would run in intranet). A straight forward way is rewritting them in one of the .NET technologies. But a suggestion about using Google Web tookit has popped up and the argument is that it would help creating applications that would run in a browser on both desktop and mobile devices.
One of the key problem that I see is that GWT is a large abstraction over Javascript. This will require the team to learn GWT, Javascript, IDEs etc as their experience has been primarily Microsoft technologies and not Java. It would be easier for them to learn .NET technologies instead of GWT.
I do not have a depth of GWT and its drawback pittfalls and do not know about a parallel Microsoft Technology that I should investigate.
So I would appreciate if people here can share their views or experiences using GWT or equivalent Microsoft technology.
Questions like this are subjective, so you wont get one straight answer. Are you rewriting the unix/socket backend as well? Or do you intend to put a web service wrapper in front of the sockets because without this I cant see a web / internet solution working.
For my money if you are a .net/microsoft house then a MS technology is the way to go. MS is currently backing jQuery which is a client side javascript framework, but there are others like extjs. If you stick with MS and a server side solution then ASP.NET MVC is currently gaining a lot of traction. MVC and jQuery work well together imho.
If you set up a REST based web service layer for your backend it means you can even get away with flat html front ends powered by any javascript framework without needed a server side web rendering technology at all. For REST you can look at .NET WCF if you stick with MS tech.
Given that you've been working with MFC and VB, .NET is going to be a new world to you as well. At least with Microsoft you'll have strong development tools and learning resources that you'll need. Not so sure that will be the case with GWT.
But also, if one of your developers wins the lottery and leaves the company, you'll have fewer problems finding another MS developer to replace him.
Given you guys are a Microsoft development shop, I'd stick with the Microsoft stack (unless your developers really want to learn something new - in my experience that's rarely the case).
Anyway, I thought I'd bring up that Microsoft had an "embraced and extended" version of GWT called Volta that they release 2-3 years ago. The idea is that it takes C# as its source file, and compiles that to Javascript.
I suspect the project is dead (I can't seem to find a whole lot of information about it), but you may want to verify that. I brought it up because you guys seemed like a Microsoft shop who's interested in GWT.
Based on your provided information I think it is better to use fromMicrosoft Technologies instead of Google Technologies.
This will reduce Cost (include Time to learn and also the budget and etc)
on the other hand, Silverlight goes on the windows phone mobiles with (WinMo7) so your application will run as the same in Cellphones too. So my sugesstion is to use Microsofts Technologies.