Develop Reference

Application server use for non-web applications

I am interested in understanding "best practice" for the use of application server (for example Glassfish). I have a medium size application that consists of various components that consume and source web services. These components are hosted in a Glassfish environment.
I now have a requirement for a simple scheduled function that copies data from one database to another. That is, it requires no web type functionality. It could easily be built as a simple application (say around Quartz) and deployed in the same Glassfish server with the other components. I understand that this is a simple question, however is this a "reasonable" approach or should it really be a stand alone application running independently from an application server? I guess the more general question is "What are appropriate uses for an application server and what are not?"

It could just be a shell script called from cron...
Seriously, not a very good use of an app server UNLESS you're going to get some sort of monitoring or load distribution out of it. But it sounds like this is really just a batch job in which case you should do the easy thing and just write a script or a simple app with a main method that you either call from cron (or something similar) or run from the command line with some sort of embedded timer (or a sleeping thread).

What server platform to choose for periodically running a standalone (Java) program?

I need to develop a game server that will run periodically (e.g., triggered by a CRON job every five minutes or hour as appropriate). Once started up, the server will access all of the current game state (fetched through REST from the game's data servers (Stackmob, Parse or similar), do the processing of player actions, and then POST the results back to the data server. In other words, it will be doing a lot of HTTP requests, but does not itself necessarily need to be a web service.
I've been considering multiple ways of developing this.
I do not feel for setting up a server myself, so I need to find a service to run this on that permits the workflow I would like.
The game engine is Java, so something that works neatly with that.
Will need to GET and POST data files, so access to static files would be needed.
Most of the services that exist which provide something similar to what I require are directed at web services - which generally means that one needs to jump through some hoops to get things to work.
Google App Engine, for instance, would require that I implement this using backends (since the game server could potentially run for more than 60 seconds), and isn't particularly happy with the idea of static files.
Amazon EC2 would seem easier to develop on (again by building a web service frontend, of course), but there seems to be relatively poor support for CRON.
Generally speaking, it feels like I want to shoot some sparrows with a slingshot, but all the services are offering me cannons. Are there any alternative platforms/frameworks beyond the big two mentioned above that would be suitable for something like this?

You could try Heroku. They support Java. If you created a project that used a single worker dyno then the hosting would be free (see link).
The process would be running continuously, so you might want use a Timer for periodic execution. You could also use Quartz, but it might be overkill.
Edit:
Here's some links that might help get started:
Running non-web Java processes on Heroku
Heroku Java quickstart - this is for a web app ('web dyno') rather than a 'worker dyno', but it may help.
java.herokuapp.com has links to some example projects (again web apps rather than workers)

How about using EC2, but rather than putting the scheduler in the instance (which won't work because the instance can go away at any time), putting it in AWS? Like this guy:
http://alestic.com/2011/11/ec2-schedule-instance
Alternatively, if you manage your EC2 instances through Ylastic, it looks even easier:
http://blog.ylastic.com/scheduling-tasks-on-the-aws-cloud
Although you'll have to pay for Ylastic as well as EC2, i imagine.

I found a nifty way of writing something like this in Groovy with Maven. You can write a multithreaded Groovy script to pull the stats, do the updates, etc. and then have maven's assembly plugin assemble the whole thing into a self-contained, executable jar file that can be called by a CRON job. One nice thing about Groovy is that its syntax allows you to do this:
def google = "http://google.com".toURL().text
which will turn the string into a URL and handle all of the details of turning the URL into a HTTPURLConnection and getting the raw text.

You could develop the app as a standalone Java program first and then worry about where to deploy it later.
To develop the app you could write a simple Java program that uses HtmlUnit to talk to the external web services. The job could be internally started via Quartz. If you really wanted to start the job externally via CRON, you could have CRON run the app, passing in args. The app would then run and exit.
Alternatively, you could have the app always running and have cron run a bash script that triggers the job in some way.
Essentially, all you need to deploy is a Unix machine so you could use AWS.

running jar as webservice?

Can a .jar be run as a webservice?
Since jar file consume a lot of cpu on my development machine, I would like to call and run it on another machine via network. Need advice on this, what is the best way of doing it?
Thanks.

You can create a web service to run a Java command line application. It is relatively straightforward, but you will need to code a servlet wrapper that (typically):
maps HTTP requests and their arguments onto calls to your application, and
turns the output from the application into something that a web browser can handle.
And there are significant limits on what the service will be able. For instance, it won't be able to read or write files into the local file system of your development machine.

can you use JVM and use something like tomcat or some other java container?
lots of docs out there for that kind of stuff, most containers even have their own samples on how to create webapps.

Pure Java app on Glassfish?

I may be barking up the wrong tree here -- it's relatively easy to wrap a vanilla Java app in a daemon/service -- but it'd be really helpful for deployment if we could push pure Java apps onto a Glassfish server and have them start up automatically.
We use JMS to connect this app to several other beans living on the Glassfish server. We are actually using glassfish to "deploy" it to the production machine, but it doesn't start automatically. Have been looking into JCA, but it doesn't seem like quite what I'm looking for.
Thanks!

If your 'pure Java app' is packaged as .war you could add a ServletContextListner to your app that gets called when the application is loaded and that performs the starup of the application...

How to deliver a Java program locally through a browser

I want to write an application that runs entirely locally on one machine - there is no need for connection to the internet or to any external machines.
I was thinking that it would be a good idea to use a web browser as the platform for this application so that I would not have to mess around with lots of UI stuff - I could just knock together the web pages fairly quickly and take advantage of CSS to get consistent styles throughout the application.
However I want to interact with a MYSQL database on the machine in question. With this in mind I was thinking that I could somehow use Java to process the information that the user inputs from the application and communicate it to the database via JDBC.
I know that I could use an applet to do this but the downside to that is that I would like the user to be able to save files to the local machine - and I have read that applets run in a sandbox which prevents them from gaining any access to the local machine.
I also know that I could use PHP but I would like to take advantage of object oriented design which Java is perfect for.
Does anyone have any thoughts, suggestions or links to tutorials/webpages which could help me to decide how best to go about this.
Any thoughts are very much appreciated..

I know you said you don't want to mess around with GUI stuff in java, but have you looked in to java web start? It does almost exactly what you need; a user clicks a link through a web browser and your application is deployed on their machine, it even checks to make sure the right JVM is used. Because it is a full application and not an applet, your app won't be sandboxed, and you don't have any access restrictions in your program (other than the normal java stuff..), and for example, it would be easy to do what you mentioned and talk to a mySQL DB. The only downside, is what I mentioned earlier, is that you would have to design a UI in java.
Web Start Wikipedia Page
Sun FAQ on Web Start

Grails may be a useful starting point. It'll provide you with a web server solution that's standalone, and it'll look after the JDBC requirements and the CRUD (create-read-update-delete) capability via dynamically generated web pages. It should take minimal effort to put together an app providing your database interfacing via web pages.
(fyi. Grails is the Java equivalent of Rails)

If you feel comfortable with Java EE-based web development, you could probably just bundle your application with Tomcat or Jetty.
If you do not want to run standalone servlet container just for one application, you can also embed Jetty into a runnable Java application (see documentation here).
Either way you can leverage existing Java EE frameworks (Spring JDBC, Hibernate, all those web frameworks) for abstracting away technical complexities, although with embedded Jetty, you'd probably need to write some kind of integration layer for the web application framework of your choice.

I think you should give Restlet, a lightweight rest framework a try. The tutorial shows you how to start a local webserver, and by that deliver a "Hello World" through the browser within minutes (no joke!), and there's plenty of extensions for any kind of need.
In combination with Java Web Start by which you can deploy and start the application to the local host this should be what you need.

as someone suggested already you can use embbeded jetty server on your application and just let your user to start it using somekind of shell script or batch script. You only need to make your layour directory complaint with a Java Web Application and your on it. ie:
MyApplication
app/
WEB-INF/
lib/
classes/
web.xml
start.bat |
start.cmd - depends on your client OS
start.sh |
Then you should only need to take care of launching Jetty in your start.[bat|cmd|sh] with your app as your webaplication context and your done!

Using JDBC doesn't mean that you have to write an applet, you can use JDBC in any kind of application: a desktop application, a web application, EJBs, MDBs, etc.
You want to use a browser and Java on the server side? Then go for it and use Servlets / JSPs. Consider maybe using an presentation framework (Wicket, Struts2, Spring MVC,...), Hibernate for data access and Spring for other facilities and wiring. Grails is a good idea too.
BTW, I'm not a PHP specialist but PHP has object-oriented capabilities (introduced in PHP4 , enhanced in PHP5) so you won't sacrifice everything if you choose PHP.
So it really depends of what you want to do. If you want to write some Java (webapp or desktop app): choose Java. If you want to put quickly a few web pages in place and have an apache server, choose PHP. If you look for really high productivity, go for RoR or Grails.

You can try GWT + Google Gears
GWT is a GUI toolkit similar to Swing for the browser. Google Gears is a browser side database. Your app is completely in Javascript in a single HTML file and cross-browser compatible.
GWT app can make Server calls and Gears can sync up with a Server database. So you need not restrict your app data completely to the local desktop.

If you're interested in some experimentation, like new stuff and would like to reuse the plethora of Java libs (including JDBC) then you might be interested in the lift web framework, which is Scala-based.

If you want to do it as an applet you can. Sign the applet and give it permissions to the local network (to connect to the MYSQL server that way)... that should be possible. Here is a tutorial on it.