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How to upload jar files in webswing?

I want to convert my Swing application to web application. Getting help from How to deploy swing application on web browser?
Please have a look to second step of first answer ("Install this [AjaxSwing] application in your system"). Where can I upload jar file and how?

You don't actually upload a jar file, I think the related answer is misleading. Webswing is a software you download and install on-premise. It starts a web server which serves your application on a web page. All you need to do is create a configuration where you specify the path to your jar file. As Gilbert pointed out, you can get the idea when you read the Webswing documentation https://www.webswing.org/docs/20.1/start/quickstart.html

Where to upload an image/file to make it appear on HTML?

Well,I'm working on an Eclipse Dynamic Web Project under Tomcat.
I'm trying to make a web application/site.In a jsp/html page,there is a form where a user can upload a photo.
I handle then this action from a servlet that has to store this image/file somewhere so as to make it possible the image appears whenever I want on the site.
Here is the problem.I started by storing it on my file system,(path in a database) but when I wanted to retrieve it the page didn't appear.
I guess the reason is here:
Why can't I do <img src="C:/localfile.jpg">?
Then,I tried to store the file in the eclipse project folder(WebContent/folder) where I've stored manually some images that do appear.
File folder=new File("/TED/res/img");
File file=new File(folder,fileName);
System.out.println(file.toPath());
Files.copy(fileContent, file.toPath());
But this exception happens:
java.nio.file.NoSuchFileException: /TED/res/img/2017-08-13-123524.jpg
It's one the line of files.copy command which means that
new File(folder,fileName) that I tried failed
What should I do? From what I've read,I understood that also saving file in the IDE's project folder is also wrong but what other choice do I have?

Ultimately, the project will be deployed to a server. As such, there are three distinct issues:
Uploaded user content location: content like images should be uploaded to a folder outside your web app (project). Images inside the web app (project) should be those that are necessary for the application and provided by the developer, not user-generated.
In Eclipse, during development and testing, you will want to serve these images through Tomcat. There are many ways to do this. Tomcat configuration is probably not the best for this - please read the answer and discussion here: Simplest way to serve static data from outside the application server in a Java web application
Once the application is deployed to the server, Tomcat will most likely run behind a Web server like Apache or Nginx. In this case, the external image folder and its contained files can be served directly by the Web server. Even if you implemented a servlet in (2) for local testing with Eclipse and this servlet is part of the code that is deployed, it will not be invoked as the URL will be intercepted by the Web server before it reaches Tomcat. For example, if your uploaded image folder is C:\images on your development environment, it can be served by the servlet using the technique in (2) as /images/*. When deployed to a server, the Web server can be configured to servet /images/* from /srv/content/images and this request will never reach Tomcat.

How does Jetty deployment on Azure App Service work?

I have a Java web app that I run on an Azure App Service instance. To deploy it, I use a Bitbucket repo with a .war file inside it. When I commit a new .war file to this repo, it is supposed to be deployed automagically by the service. However, more often than not, I have to either restart, re-deploy, or even upload the .war file via FTP for the deployment to be completed successfully.
I have a single Jetty instance residing in this service, hence my .war file is named ROOT.war. AFAIK, when uploaded to the service (whether via Bitbucket or FTP), this .war file should be unarchived into the same directory, which is /site/wwwroot/webapps. In my case, this doesn't happen. The web app works with the ROOT.war file sitting alone inside /site/wwwroot/webapps. And every once in a while, I get a ROOT folder under /site/wwwroot/webapps, with two default files index.jsp and background.png. I don't have the slightest idea what causes the ROOT folder to appear with these default files. The only clue I have is that it happened a couple of times after I changed an environment variable.
Also after the ROOT folder appears with the empty server files, the only way I can re-deploy the app is to manually delete this ROOT folder via FTP or the console provided in the portal, and only then my re-deploy request succeeds with my web app.
So, if it isn't clear enough, my question is what is going on here? I can't make anything out of the behaviors I'm facing. I feel like I'm using this Azure service blindly, and can't get to fix anything when something goes wrong. Are there any resources that may explain what happens in the background when a web app is deployed?

So, Azure API Apps are a PAAS, not IAAS service. You can access the PaaS platform by coming to yoursite.scm.azurewebsites.net, where you can browse the file system in CMD or Powershell, and you can see the running processes. This may feel like you are on a single VM, but you are not. The data you see here is replicated down into your API App instances. You can control how many instances you have through scaling your API App.
I have commonly seen your issue with deploying, then ROOT being empty(working internally to see this fixed...).
The best method that works every time for me, is to stop your API App, manually UNZIP your ROOT.war. Move the files into /ROOT/, then to start your API App.
You can simply place ROOT.war, and let the system unpack it when you turn it back on, but this can sometimes lead to that empty ROOT directory, then requiring another restart.
All of this has me moving to Spring-Boot instead. No unpacking required. Simply configure your web.config and drop the jar file.
https://learn.microsoft.com/en-us/azure/app-service-web/web-sites-java-custom-upload#springboot

I had the same problem. The solution is to call the endpoint after de deploy.
Stop the Azure App Service.
Deploy the ROOT.war artifact in the /webapps folder.
Start the Azure App Service.
Call the URL of the App Service once.
The four-step is very important and start the process that you mentioned before (the automagically deploy).
I lost a lot of time figuring out what was the problem.

Tomcat needs to be restarted due to jasper reports

I am using Jasper reports in my application for generating reports.
I have also provided the facility to download the reports in Pdf/Csv format.
But the problem I am facing is that, whenever I upload a new war file
(with or without the changes in the JRXML files used for designing the reports) I have to start/stop the tomcat server. Unless I do that, I am not able to generate the reports. There are no logs seen nothing happens and the
reports are not generated as well. As soon as I restart the server, everything starts working like a charm. Reports get generated and everything else is fine. Why is this so? Why do I have to restart the server every time I upload a new war file? And this is a random behaviour.
Its not always necessary to restart the server the moment new war file is uploaded, it may be required to restart the server after some time.
(But it has to be restarted once in the new war's lifetime)
Is there any bug in Jasper reports regarding this behaviour?
How can I avoid this server-restart issue?

You can configure reloadable contexts in server.xml but it only monitors /WEB-INF/classes/ and /WEB-INF/lib. If you want to re-deploy your webapp you can restart tomcat as you are doing or use tomcat manager

Where do I put application generated HTML reports to that they don't get removed when I deploy a new WAR file?

I have a simple web application which lets the user upload local user data and then they can generate HTML reports from that uploaded data. Once the HTML is generated, I display a link to the report which they can click on to view in their browser or they can share the link with others.
The problem is that I am currently putting the "/Upload" folder in the "WEB-INF" folder because I don't want that folder data accessible to the outside world. I am then putting the "Reports" folder in the root directory of the web application. This work fine in that I can deploy the WAR file to the their server, the user can upload the files, and then request for HTML reports to be generated. The problem is that when I send them software updates in the WAR file it deletes everyone in the /MyWebApp directory including the /Upload and /Reports folder. So then the user has to re-upload the data and they loose any of their existing reports in the "/Reports" folder.
Now I did find an answer for the /Upload folder on StackOverflow with this discussion.
Where can I put an uploading folder so that when I deploy/undeploy the site in Tomcat that folder won't be affected
But I still don't know where to put my "/Reports" folder? I thought I would have to put it in the web application context directory as I am doing now in order for the Tomcat server to serve it up as a link (e.g.: http://example.com/MyWebApp/Reports/report01.html).
The other thing to note is that this application is running on Apache Tomcat only, I don't have the request going through an Apache server. We decided to just have it running on the users local server with Tomcat because it seems easier to deploy then trying to deploy and configure both to work together. Also, there are only 2-3 people using this application per server site and with that load Tomcat seems to be doing a great job handling everything on its own. So maybe that is making the solution more difficult?
Any hep with best practices for this would be greatly appreciated.

There should be no difference between the strategy you used for placing uploaded-files on the disk with placing reports on the disk: both are files that were generated by the webapp during its deployment (forget the fact that a client uploaded the file) and need to be protected in the same way.
If you are willing to upgrade to Tomcat 7, there is a new <Context> attribute, aliases, which will allow your webapp to serve content from that directory but not delete it when the webapp is undeployed.