I've read similar questions but I still don't have all the pieces together.
Is it possible (and if yes how) to start an Apache Felix based OSGi desktop application via Java Web Start?
My main concern is that you have to specify the bundles somewhere in JNLP file if you want to enable the update checks of Web Start (which is a requirement). But the only thing I see that could help is a jar resource. But this would just add jars to the classpath, not starting them as bundles.
Any ideas?
Right, any JARs you list in the JNLP will simply be put on the classpath. There is no way to get Web Start to install them as bundles, because Web Start knows nothing about OSGi.
You could use Web Start to kick off a small launcher application, which consists of just the OSGi Framework and a "management agent" of some kind. That management agent could then use other means (e.g. OBR) to install and update bundles from a repository.
This approach would also help you to eventually migrate from Web Start entirely, which would be for the best since Web Start is obsolete and may not even be supported in future versions of Java.
Related
I'm reading about OSGi and JBoss modules. I understand the purpose of modules -- to avoid Jar hell and conflicting classes -- but I don't know where to start if I want to write a new application that uses them. Is there a kernel somewhere that I can start with, that then loads the other modules? I don't want to run Eclipse or Wildfly; I want to start fresh with my own app. Hello world for modules.
Edit: I'm using IntelliJ, and for several reasons I really don't want to switch to Eclipse. So I can't do much with answers that require I install Eclipse plugins.
OSGi would be the first choice. JBoss Modules is still much more an internal JBoss thing than a general purpose modularity solution.
To start with an OSGi application, take a look at Bndtools. This is an Eclipse plugin to make OSGi development easy. From there you can create a "run configuration" which is the definition of your application. From there you can also export the application to a single executable JAR to distribute your app.
This is a nice video to get you started.
Also, for more high level components (REST, databases, scheduling etc.) take a look at Amdatu.
Try starting with OSGi enRoute: http://enroute.osgi.org/. This is a project, still in development, to demonstrate using OSGi.
If i want to deploy one application on different servers like Open Source Glassfish or TomEE. How can I achieve that without having to include different libraries for each application server? As an example if would like to use Jersey as the rest framework and eclipselink as the persistence framework i have to make sure both support these frameworks. But in case of TomEE it's shipped with other implementations like OpenJPA.
Is it possible to ship the dependencies only with the project and not in combination of server libraries + project libraries?
What is a good way to achieve server compatibility?
Any information or link which describes a solution or help me understand why it's done this way would be great.
Thanks in advance
This is more of a application server classloading issue and usually all application servers have a provision for a configuration file which you can put in your application and instruct the server to load the libraries included in the web application instead of the one present in application server. For e.g., Weblogic has a weblogic.xml file which is put in WEB-INF of war application and where you can instruct server to prefer the application packaged libraries. For JBoss there is similar configuration file jboss-deployment-structure.xml. This way it is easier to have a self contained application which contains all dependencies even if the server has equivalent libraries. Also you can upgrade to higher version of libraries than supported by application server otherwise you have to resort to all sort of hacks.
Easy solution I can think of is using ant task to create war file for each servers. You can have at most 2-3 servers in reality like tomcat ee, jboss and glasfish. So create 3 ant tasks for each like tomcatWar, jbossWar and glassfishWar and each ant task makes sure required jars are shipped as well in the war. This is more easy and extendable solution, also easy to understand and modify for new requirements.
I am writing a java web application using spring, hibernate and mysql. The applications is getting larger so I want to break it into smaller parts e.g. smaller projects, components or which ever way possible. For example I have login and image uploading functionality, I don't want both of these to be in a single code base or project. I want to be able to use these separately almost like separate services independent of each other. Is there a way of doing this e.g. convert the image uploading functionality into a jar and then reference this jar in the actual project? How are the Enterprise projects split?
Hope it make makes sense and please advice if I am going the right direction as it is my first project? It would be nice if someone can point me to a mini example or recommend reading.
thanks in advance
Try with OSGi. If you are using Spring, then declarative services and possibly blueprint container in OSGi specs are what you need to leverage what you have done until now.
Try reading OSGi in Action by Richard S. Hall, Karl Pauls, Stuart McCulloch, and David Savage to get an insight in this technology.
OSGi is a modularazied approach for java software development that enforces loosely coupled services creation. Quoting from the OSGi alliance website:
OSGi technology is a set of specifications that defines a dynamic component system for Java. These specifications reduce software complexity by providing a modular architecture for large-scale distributed systems as well as small, embedded applications.
Hibernate supports OSGi as it can be seen here. As for the OSGi implementation, I would recommend Equinox, but many other valid OSGi implementations exist. Since your project is a web application, you could check also Virgo
Virgo from EclipseRT is a completely module-based Java application server that is designed to run enterprise Java applications and Spring-powered applications with a high degree of flexibility and reliability
and in particular,
supports vanilla WAR files, with all their dependencies in WEB-INF/lib, and Web Application Bundles, that import their dependencies via OSGi manifest metadata, via the reference implementation of the OSGi Web Container specification, based on embedded Apache Tomcat and configured using the standard Tomcat server.xml
I ended up using maven modules and maven dependency management capability. I created a separate maven project and kept adding maven modules as needed e.g. created a module for image uploading, one module for common libraries and so on.
Each of these modules are then packaged to jar files. I then import each one of these jar files using maven dependency to my main web project.
It seems to have worked great so far. Hope this is helpful for someone else, too.
Well im into building OSGi application for a while, but i can't really find some tutorials which show the way to build Desktop Application ( in any languages ) with OSGi/Karaf.
I want to use karaf because it can then wrap Felix/Equinox. Most of Tutorials i found are about Enteprise Application(WEB). So is there any tutorials, which talk about building desktop application based on OSGi/Karaf?
Here is an example of a GUI application project that uses Apache karaf:
https://bitbucket.org/lorainelab/igb-fx
Using karaf to run a gui-based desktop application decreases development time. A developer makes a change to a bundle, builds the bundle, and then uses karaf shell commands to reload just that one bundle into the running application. There is no need to restart the entire application to view the effects of the new code. This is why were are using it.
We are using OSGi because we want greater modularity in the code base and because we want to support dynamically loaded "Apps" developed by 3rd party developers who write against our genome browser API.
Sorry the main intend right now for Karaf is to be used as a Server, though it still should be possible to start some guis on top. As your already familiar with building such bundles I'm sure you most probably could use just the minor version of Karaf and place your bundles in it. I have to admit I never done this before, so I'm not really sure about it.
First of all OSGI is a component framework, it also leverages a feature missing in Java since its inception - runtime versioning. If you really need it (OSGI), it doesn't depend wether you develop a WEB or desktop application. In general I would recommend you to take a look at this documentation:
http://fusesource.com/docs/esb/4.2/deploy_osgi/Build-ModifyMaven.html
In that link you'll find how to convert an existing Maven project to bundle, check further chapters - there's info how-to deploy jars in e.g. Karaf (Karaf is an OSGI container)
Hope, this helps
Our current process for upgrading the application is to undeploy the current version, and then deploy the newly created EAR process.
I have seen softwares which have an "auto update" functionality (such as Spring Tools Suite). The software downloads the updated files automatically and performs a self upgrade. There is no need to download the complete setup again and uninstall/install the application.
I just wanted to check if anything similar exists for Java EE web applications as well?
Many servers today support hot-deployment, where you deploy the app over the running one.
This of course still needs the functionality to pull the app from somewhere.
In JBoss 4 at least (and I think it is also available in 5), you can tell the deployment scanner to watch multiple directories, so it could monitor e.g. a shared drive and when you put the application there it would see it and pick it up.
The proper way to redeploy code at runtime is to use OSGi. This is a system created to allow automatic dependency resolution. It allows e.g. for you to keep running older code for existing connections, while using the new code for new connections.
It also allows you to link to newer versions of libraries, which are loaded automatically.
See https://docs.jboss.org/author/display/AS7/Helloworld+OSGi+quickstart for a nice quickstart for using OSGi with JBoss 7.