We currently have an Java application that can be deployed on clients or run as a shortcut from the server. We have intermittently received ClassNotFound exceptions when running the JAR from the server which looks like Windows dropping the network connection with only part of the classes from the JAR loaded (user opens a different screen then the problem is apparent).
I am currently looking at the Web Start technology to allow us to run a single shortcut.
However the application has several folders it requires to be in the same folder the JAR is launched (for configuration, logs, etc.). These folders will require full access for all users to allow them to write log files. There are lots of configuration files under the configuration folder hierarchy.
The application also requires access to environment user settings (such as getting their user folder). It also requires certain command line parameters (including which folder to use for configuration, log file location, java memory usage, etc.)
Edit
The application also contains a reference to 2 signed JARs. These are:
jh.jar
mail.jar
It looks like these are signed by SUN Microsystems. jh is used for help integration in our application whilst mail is used for email integration.
I have now downloaded the latest versions of these files from java2s.com which do not have the signed equivalents.
end edit
The application is developed in Netbeans which compiles a single JAR file and copies the dependant JARs to the dist/lib folder. I enabled the Web Start functionality in Netbeans for the application and it generates the JNLP file.
Bearing everything in mind is Web Start the way to go for an application like this?
Can you include folders in a Web Start deployment? I could not find anything to do this in the XML structure for a JNLP file.
Cheers,
Andez
Yes, you could use WebStart for this.
Permission:
If you need permission to the file system, you have to sign your jars and put the all-permissions tag in your jnlp.
Arguments:
Arguments can be provided by using the arguments elements in application_desc.
Folders:
I'm don't think you can include folders in the WebStart application, but you could put the config files in a jar and read them from there, or extract them on startup.
ClassNotFoundError:
We have intermittently received
ClassNotFound exceptions when running
the JAR from the server which looks
like Windows dropping the network
connection with only part of the
classes from the JAR loaded
Does not sound plausible to me. per default, all jars will be downloaded before the application starts. If you set "download" to "lazy", the jar will be downloaded when first needed, but I would guess it will be downloaded completly then.
You can provide read-only resources for Java WebStart. Getting the log back is harder. I would suggest looking into a centralized logging solution, using one of the standard appenders in the log framework you use.
For a Java Web Start application it is always advised not to create files or folders in the class path. Recommend user's home directory to store your settings or database files.
Related
I am using Websphere application server 9. I have some external files that are not supposed to be packaged as part of war file, but those files should be available for Websphere application server in its classpath. i.e the external files should be available in the classpath.
Can anyone tell which directory of Websphere will be available in classpath by default so that I can keep all those files there?
If the above option is not available, I will keep my external files in some location of Websphere server, but how to tell the server that "hey! you should look for specific directory and make it available in your classpath"?
There are several directories which are on the classpath by default like %WAS_ROOT%/lib/ext or %PROFILE_ROOT%/properties however it is not recommended to use them for application specific files.
The recommended approach would be to create Shared Library where you could define directory where you want to store files that would be accessible and then associate it with the application.
Check these links:
how-create-shared-library-and-associate-it-application-server-or-enterprise-application
managing shared libraries
I have a JNLP application that is executed from Java Web start applications. The application uses eParaksts digital signature. All the required jars are loaded and signed. They work properly. However, the jnlp requires certain eParaksts licenses to be configured in the class path as they are read by the third party libraries.
When the JNLP is executed as standalone, it is able to read classpath files mentioned in the config folder but unable to read when executed using web start. How can I make my JNLP read this files?
What do you mean when you say
When the JNLP is executed as standalone ...
You meant, when the application is run as a standalone Java application?
Java Web Start application cannot work with configuration folder/files the way a regular Java app does (see section resources Element). If these eParaksts licenses are files, put them in a jar and deploy it as a JNLP resource. They should be then in the classpath of the application.
I have a Java desktop application and now we distribute it as a jar in a installer of a main application (currently the Java application is only an importer/exporter). But as the jar is updated more often than the main application we are thinking of making it run through Java Web Start so it's updated independently when it start.
My question is how can I distribute it in the installer so if the user don't have internet it use the jar bundle in the installer (and copied in the main application folder) but when he launch and have internet, Java Web Start update it?
Edit: I have think in making two JNLP files one for local launch and one for online launch so it get updated, but then they need to share the cached jar so isn't installed two times, and I don't know if this is possible.
Edit, more explanations:
Maybe I haven't explain it very well. I have a native application and is distributed as an MSI, from download and through CD. With this application we distribute the Java application (a jar) that the main application used to exchange data to other formats. The MSI installs both the native app and copy the jar (not really install). Now if the user have internet and a new update is published, the complete MSI is downloaded and installed (updating the installation). Ok?
Well, we like to update only the jar in a more fashion approach, with Java Web Start, so it's updated when the jar is run independently of the main app. This have the problem that if we only deploy it as Java Web Start, if the user install the app in a computer without internet (for example carrying the MSI in a pen-drive or cd) he will not be able to use it, because as he don't have internet he can't download the jar.
And now is when my question come, can I deploy the jar in the MSI but execute through a Java Web Start so if the user have internet it get updated but if he doesn't have internet it still can use the bundle jar in the MSI?
..can I deploy the jar in the MSI but execute through a Java Web Start so if the user have internet it get updated but if he doesn't have internet it still can use the bundle jar in the MSI?
OK, I am formulating a plan here, this might be doable.
Let us presume that the MSI is capable of doing the following things.
Install a JRE if missing or too low a version available. The JRE needs to be included in the MSI (to avoid requiring the net).
Unpack the JWS launch file and Jar(s) (and native..) to the local file system as temporary files.
Invoke the javaws tool using 'IMPORT-OPTIONS' to set the code-base to the place in the local file-system they were unpacked.
At this point, desktop icons and shortcuts should be installed, and the program ready to launch. It is vital to specify a few extra options in the JNLP - specifically offline-allowed to ensure the app. can still be launched if the internet is not available.
Caveats: I don't have any experience with MSI, and my experience with using the import options is limited to calling them from build files (during development).
I earlier got to create a simple RESTful webservice on my localhost using Eclipse IDE, Tomcat, and JAX-RS libraries.
I am now trying to move the same on to a different unix server which has Tomcat installed. I am not knowing how to get started as in what is equivalent to creating a "Dynamic Web Project" that I do in Eclipse. Do I need to just create a directory myself with all the sub-directories as created by Eclipse? Should this directory be placed in webapps folder in Tomcat container. Should META-INF and WEB-INF also be created by myself?
Where should I put my Java classes?
Can somebody please clarify this or direct me to any documentation about the same.
You need to package your application in a WAR file.
The Sun Java EE 6 Tutorial has a chapter deciated to packaging.
It's pretty easy to export a web application as a war in Eclipse.
Dynamic Web Project (right click) => Export => Web =>war file =>war export dialog
Creation of web application archive - WAR is the solution for your problem,
but take care about all libraries that you need there.
You can easily extract (unzip) WAR file content
and check your project structure and libraries needed
and they will be in WAR's WEB-INF/lib.
Make sure that both Tomcats are set same way,
make sure your code is all OS friendly (users, file paths, permissions)
Always write some test simple code that will run up on app start,
and check all dependencies and libs, system clock, outside world network communication, so you can trace it in web app console or logger easily.
regards
I have installed and configured tomcat+solr on my personal linux machine and windows as well. I was able to get them working fine. I'm very new to Java and how the file structure works. (i.e. knowing where to put war files and what WEB-INF is) So now that I am ready to install solr and configure it on my clients shared hosting plan, the directions are different from what I did before. I dont want to mess this up and apparently the webserver reboots daily and I dont think I can do it manually which means I have one shot at this every day.
Here is the directions for installing a tomcat servlet on his hosting provider:
http://www.apluskb.com/scripts/Where_do_I_put_my_answer1186.html
As you can see I need to install solr under the html/WEB-INF directory, but read what it says.. its very confusing:
"All Servlets should be uploaded in the /html/WEB-INF/classes directory. Any unpacked custom classes and resources should be uploaded in the /html/WEB-INF/classes directory, while classes and resources packed in Jar files should be uploaded to /html/WEB-INF/lib."
uhh... so which is it? /classes? or /lib? I dont think they explain that very well and I'm a little confused by this statement. Also what exactly do I install? With a normal solr install, solr is put somewhere else, the war file is copied into tomcat and the rest of solr is referenced using some kind of XML configuration file.
Also, since I'm a little new to Java and servlets, can someone explain the tomcat file structure to me (in great detail will definitely get you a +1 from me) and where things should go and why?
Thanks in advance!
Web application structure is defined by J2EE spec, it's not limited (or specific) to Tomcat per se. Here is a detailed tutorial covering its layout. Briefly, however, it's as follows:
There a base (root, home, whatever you want to call it) folder which serves as root of web application, everything else goes under it.
All public stuff (html, images, CSS, javascript, JSP, what have you) goes under that folder (directly or via subfolders).
There's one special folder, also located directly under root, called WEB-INF. It contains non-public stuff, like application descriptor (web.xml), classes (which go into WEB-INF/classes folder), libraries (WEB-INF/lib) and possibly configuration files.
Application can be deployed either using expanded structure above or as WAR (web archive) which is basically an archive containing everything above starting at root folder level (but not including root).
The distinction between classes and lib folders is simple: all packaged libraries (JAR files) need to go into lib; all unpackaged classes (and resource files that need to be in classpath) have to go into classes preserving their directory structure (e.g. com.mypackage.Blah class should go into classes/com/mypackage/)
In your case, it looks like you can only have one web application deployed and it has to be deployed to /html folder. If you're deploying a war file, you need to extract it to that directory (e.g. from within that /html folder run jar xvf solr.war or whatever it's called).