I have encountered many different ways to turn a Java program into a Windows Service or a *nix daemon, such as Java Service Wrapper, Apache Commons Daemon, and so on. Barring licensing concerns (such as JSW's GPL or pay dual-license), and more advanced features, which one would you recommend? All I intend to do is convert a simple Java program into a service; I don't need anything fancy, just something that runs as a service or a daemon, so I can start it or stop it in the service manager, or it runs for the lifetime of my *nix uptime.
EDIT:
I've decided to make this community wiki. I didn't start this question with an intention to find an answer for a problem I really had. I was just doing some reading and researching and chanced upon this question, so I was looking for recommendations and the like. Sorry for not doing this sooner or doing this at first. I didn't know what community wiki was for when I first started, and I completely forgot about this question until now. Many thanks for the answers!
I've used JavaService for years and have been very happy with it. Very simple.
That said, we're switching to JSW for the next major release - its multi-platform support is awesome. Also, having all of the params in a .conf file vs the Windows registry is a major plus. But if you're only looking at Windows, JavaService might be a good way to go. (no experience with Apache Commons Daemon)
On Unix, I tried and quite liked daemontools when I set up a VPS to run Tomcat instances.
Using daemontools, I could write a fairly simple start script and have the Tomcat process run as part of my regular system startup routines. I was running several different Tomcats under different user IDs, to support private JVMs for a couple of sites.
Of course, this is all possible with a SysV style init script that runs jsvc, but having tried the former I found it much easier to set up the daemontools alternative. Also, I was using daemontools across the board for a VPS to try to reduce resource usage as much as possible. The biggest downside to daemontools was I couldn't find a way to indicate a dependency between services easily, but it hasn't caused problems in the end as nothing falls over just because it takes a few extra seconds for the database to start.
Related
We would be in near future implementing a solution to modernize our iSeries applications
written as RPG programs with some stored procedures, and our preferred way is leveraging the latest and greatest of what Java has to offer in this space.
From googling and checking other questions here on STOVFlow, JTOpen seems to be the defacto
library/toolset which has worked for most and I was encouraged to see that Tomcat runs on an I-series box with out any issues.
With this as the background, I am thinking of the following as the high level sol arch
Install IBM JRE and use JTOpen's capabilities to invoke RPG Programs and in some cases directly call the stored procedures running on DB2
Have Tomcat host a modern web application built using Grails and other frameworks (Camel, Smooks) to provide an application logic layer which would fill any mediations, transformations required for the old functionality to be offered to the user from a browser
Questions-
If any one of you has been involved in such an exercise, please share the pitfalls with this approach
Is there a significant performance drop with respect to response times for the end user?
Would it be better to some how expose the JT400 code as web services and run the web app on a different machine altogether consuming these web services?
Be very careful with calling RPG from Java because RPG is not threadsafe without some changes.
When I was at COMMON, the best product I felt on the market was Profound UI. There are several others from a variety of vendors. Most of these products do not use Java. Java on the i tends to be slow. (There are things that can be done to make it faster, but native is always faster.) You'll pay the price for these products, but just imagine how much time it would take you to do this yourself. For the above, I was quoted in the $20+ thousand range. But like all i products prices vary greatly based on system.
To directly answer your questions:
I have been doing research on modernization as time allows, the products weren't quite there yet (at the time I looked) to use it for what we wanted to use it for (before COMMON 2011). Now it looks like it might work.
This really depends on your system. A newer system will have less problems than an older system. Web will always be slower than the green-screen. Hands-down entry people won't like it. Executives and younger people will love it.
Your slow point is running the business logic. It wouldn't matter which server the HTML is coming from.
I've found that for all practical purposes an AS/400 behaves like an AIX box seen from Java code, and you must use jt400 (jtOpen) to communicate with the AS/400 specific features like data queues, files etc. This works pretty well, but the slowness of invoking the JVM pressures Java based solutions to be long running.
Note also that QTEMP is generally unavailable as a mechanism to keep state due to the nature of prestarted jobs.
Under V6R1 Java 6 is available and runs pretty well in the "new technology" edition. You can then run almost all Java based solutions, including web servers like Jetty in it. Note that Java defaults to code page 819 when accessing IFS files directly. Windows clients using AS/400 as a network drive uses a compatible code page.
Two Java programs have to communicate with each other, To do that I found two possibilities
Using Sockets
Using JavaSpaces
After looking into the description, I found out, that JavaSpaces is apparently the better solution. Sadly, I can't get it to run. Ever totourial roots me to another installation process, to other files and so on.... :(
How to install JavaSpaces, where to download them etc?
If someone offers me a better solution for it I'll be thankful to (JavaSpaces seems to be from 2005)
this are the websites I found so far:
http://www.jroller.com/matsh/entry/intreagued_by_javaspaces_try_blitz
(Installation description, not working...)
http://www.jini.org/wiki/Main_Page
(Download links are broken)
http://www.jarvana.com/jarvana/inspect/com/sun/jini/jini-starterkit/2.1/jini-starterkit-2.1.zip?folder=jini2_1/
(Download of jini starter kit)
For one quick start using GigaSpaces, a commercial JavaSpaces product (with a community edition available), see http://www.gigaspaces.com/wiki/display/XAP8/Data+Grid+Quick+Start
Also see http://replay.waybackmachine.org/20070202031207/http://www.theserverside.com/tt/articles/article.tss%3Fl%3DUsingJavaSpaces and http://www.theserverside.com/news/thread.tss?thread_id=42164 and http://www.enigmastation.com/?page_id=425
JavaSpaces is great, IMO (I'm biased, as I work for GigaSpaces... but then again, I work for GigaSpaces because I think the underlying technology is great.) - it's got a very simple API but the transaction model is actually pretty strong, and it's very fast. It's simpler and stronger than JMS, and has a simpler deployment/connection model.
If you're GigaSpaces-averse for some reason ("yikes, someone makes money from this") you can look into Blitz as well.
In Feb 2009 another user on SO mentioned, that GigaSpaces is a mature version of JavaSpaces.
Looking at that older question, I start believing that JavaSpaces is dead..!?
Have you considered also using something like RMI where it becomes transparent the fact that you are invoking a method on a remote system?
Or JMS where you just send and read messages -- and the infrastructure routes them to the right place/process?
Or how about another approach where you have a network cache (e.g. memcached) where both processes can put and get items to/from the cache -- thus allowing for inter-process communication to a certain extent?
open ended question I realize.. and probably well documented somewhere!
I used to write a lot of Java server code way way back - mostly banking etc...
I have been using mostly a windows platform for quite some time.. so I am about to re-embark on the Linux/Java/PHP/MySQL travels...
Just wonder, given the administration for Windows Server, is there anyone out there who has found some good tips.. i.e.
Choice of Linux flavours that might be easier to move to from a Win Svr background
Any LAMP stack tools that might ease the process of installation/setup..
A Java server implementation that is good for beginners to get up to speed.. all I can remember is things like JBOSS etc!
Any thoughts or pointers gratefully received!
I would suggest using Ubuntu as the Linux platform. It is both user and developer friendly.
You might find these directions helpful: http://www.unixmen.com/linux-tutorials/570-install-lamp-with-1-command-in-ubuntu-910
I plan to start learning a Java web framework (I love the Java API) I have already used Rails and Django.
I want something close to Java but without all the complexity of J2EE.
I've found 2 frameworks that could be good for me:
Grails
Grails looks great, it uses Groovy which is better than Java for web application (I think..) but it's slower than pure-java based frameworks (Hibernate, Strut, Spring) It looks pretty simple to deploy (send .war and it's ok!), the GSP is great! It's a bit harder to debug (need to restart the server at each modification and stacktraces contain a mix of Java and Groovy traces which is not always the easiest to understand)
Play!
This framework also looks great; it's faster than Grails (It uses Java) but I don't really like how it uses Java, it modifies the source code to transform the property calls as setXXX/getXXX, I do not like that... The framework also has a caching function that Grails does not have. I don't really like the Template Engine.
It's also easer to debug (no need to restart the server, stacktraces are clearer)
What do you recommend?
I am looking for something easy to learn (I have a lot of Ruby experience, not so much Java experience but I love the Java API), fully featured (That's no a problem with all the Java Library available, but if it's bundle and integrated I prefer), has good scalability and is not too slow (faster than Ruby) Ideally I would like to use a framework with a decent community to easily find support.
PS: I am not interested in JRuby on Rails
I switched from Grails to Play and I never looked back. My biggest problem with Grails was overall robustness and developer usability. Most of the time I got bitten by the fact that Grails glues together the usual stack of Spring MVC and Hibernate while trying to hide this fact and giving you a Rails-like API (personal opinion of mine). The problem with this is, once something goes beyond the trivial samples, it easily broke and didnt work for me. Developing with it was like walking on eggs (for me). Whenever I googled for documentation of a feature I needed, I was not redirected to samples, tutorials, blogs, but to the Grails JIRA explaining me why the feature wouldnt work for my use case and that the bug was unresolved since two versions before the one I was using.
While that may not be the overall experience for every developer (I am not writing this to bash Grails, but to give my experiences with it here), I needed something that helped me and would not stand in my way or break down on me when I needed it the most. Thats when I found Play and I have quickly migrated my app to it after I found out about it (around the ~1.0 release).
So far it has been a great ride and for the first time in my web development career, I have stopped looking at other frameworks trying to find something that I would like better.
If I had to close with one thing that Play did better than Grails - at least for me - it would be the fact the Play is built from the ground up with developer usability in mind. It does not sacrifice ease of use for enterprise buzzwords. It has the guts to throw away what does not fit into this paradigm (e.g. ditchting Servlet-based runtimes during development for faster turnaround). It is willing to make compromises in order to guarantee awesomeness. And that is something I have only seen in communities like Rails or Django before I found Play.
I'd suggest Grails. It has a bigger community than the play framework does (~350 plugins covering pretty much every basic need). Also, grails is written almost completely in Java, it just lets you use Groovy for your domain specific implementation.
If you do run into a performance issue where the groovy pages that you've created are the bottleneck, you can always just switch to a Java implementation. Then you're in the same boat that you would have been with the Play framework all the time. You've optimized your development time by putting off the coding of things in Java till you know that you actually need to do it (which, in my experience is very rare).
I'm also not sure where you heard that you need to restart your server for each modification, but that's actually not true. Grails supports reloading of controllers/gsps/services/domain objects, etc without restarting your server.
The mixed stacktraces can get a little long, but tool vendors (like Intellij) have made some recent improvements that strip out all the stacktrace portions that you don't care about.
I've been using grails since the .5 days and have been very happy with the platform.
Take note that the Play! framework now supports using Scala as of 1.1
From my experience with Play it's a great framework. My favorite features are the cool controller system and the template system - both are simple but feature-rich and powerful.
However the most important benefit of Play is definitely the rapid development cycle, where virtually no reloading is needed on code changes. But if you're not careful, this greatness won't last much, and slowness will eventually creep into your code.
Why is that?
With Play there is common use of some plugins with pretty heavy initialization, notably EJB (Hibernate) and Spring. The initialization of these plugins is re-run on every code change before the new code is loaded. As a result of this, as your model and your system configuration grow, this heavy initialization starts to seriously slow down your development. In the system I used 20 seconds were a typical startup time on a virtual machine running on a kickass laptop.
What you can do to avoid this depends on your application, e.g. if you're building a NoSQL application then then EJB plugin should not give you trouble. Spring can be replaced with a custom hard-coded Java plugin, which IMHO is also easier to maintain, or run a Groovy script if scriptability is that important. In any case, watch out for these problems and kill them while the're young - and be sure not to be running your own bulky initializations on every refresh.
If you have used Ruby and Python before, you will probably enjoy Grails better than Play. It very hard to get back to Java once you are used to these dynamic languages.
There is also Lift on Scala.
Imho scala is the best static typed language and lift is a pretty nice framework (for a static typed language).
We have a Java web application and we'd like to set up some basic monitoring with a view to expanding this monitoring in future. Our plan is as follows:
(1) Collect generic information (e.g. memory and threads) about the virtual machine of the web container that application is running in.
(2) Monitor the "state" of the application. This is rather vague but at the least we'd like to see if the web application is still alive and can respond to requests.
(3) In the future we'd like to collect more information that is specific to our application. Again this is rather vague but you can assume that we might want to make certain statistics collected internally by the application available to the support staff.
Usually the web application will be deployed in a Tomcat 5.5 or 6 environment. A quick bit of searching on the web shows that JMX can be enabled for Tomcat and that JConsole can then be used to connect to the server. This gives us lots of basic information that solves point (1). Also, some information is available in the MBeans section for "Catalina" and drilling down on this I can at least, for example, see how many requests a particular servlet has received. This is not quite what we want for point (2) but at least gives us some information. There seems to be quite a lot of information there but it's rather difficult to interpret using JConsole. Perhaps there is a better tool for interpreting the MBeans exposed by Tomcat.
For point (3), it seems, at first glance that we could write our own MBeans and then make these available to something like JConsole. Personally, this would involve me learning about JMX which I'm quite happy to do but I have a concern. Having looked around I notice that most of the textbooks on the subject haven't been updated for several years and the open source tools seem to be languishing without recent updates. So my main question is a simple one. What are your opinions on JMX? Does it have a future or is it/has it been superseded by something else? Given we already have our web application but we're starting from scratch for the management console, should we choose JMX or is there something more appropriate with a better future ahead of it?
I ask this question with no personal axe to grind, I'm simply interested to hear your opinions and experiences. I'm sure there's no one correct answer but I think an informed discussion would be useful.
Thanks in advance,
Adam.
JMX is certainly a good solution here. I wouldn't worry about it languishing. Most enterprises I've worked for recently use (or have plans to use) JMX, and I'd have to hear a pretty convincing argument before choosing something else in the Java world. It's easy to write clients (monitoring solutions) for it and you can return complex data very easily indeed. Most 3rd party components support monitoring via JMX as well.
Note that you may want to consider integration with any existing management solutions (e.g. Nagios, BNC Patrol, HP Openview etc.) as well. They may not be so Java-aware, but rather prefer tests like simple HTTP connectivity for testing if a web-site is up (easy using Nagios), or integration using SNMP (which Openview talks natively).
If applicable to your situation (Java 6 update 10 JDK or later, plus on the same machine) then consider using jvisualvm instead as it can dig even deeper than JConsole.
You may find that the easiest way to do what you need is a plugin to jvisualvm knowing your application