I our application we have several bundles that are running by the Equinox OSGI framework (with Tomcat).
Currently we are passing the application configuration mostly by Java system properties.
This properties are shared across all bundles and all of them can access to the properties value.
We are trying to find other option to pass them so only a specific bundle could access a specific property.
Is there a way to do it by a Java arguments?
How can i pass a java argument to a specific bundle?
You should have a look at the Config Admin service, it is designed for this use case, providing specific bundles with configuration information. Apache Felix File Install provides a convenient mechanism to supply configuration data through property files. Probably Equinox has something similar, but felix file install should run on Equinox.
Related
I've been using Maven to deploy my bundles over a felix server.
One of the things that fascinates me about Felix/OSGi is if i have configured a component with some values and i deploy my bundle again, even though the #Activate method will be called again for that configuration but my values which i've put there before deployment still persist.
How is Felix able to achieve this and is the configuration shown at /system/console/configMgr not an instance of my Java class used to create the OSGi Component ?
It's the job of the Configuration Admin service (for which Apache Felix provides an implementation) to deal with those details. Ideally, the "how" is irrelevant because those are implementation details, but if you are running an OSGi framework in a specialized environment (an embedded device for example), you would have to select a Configuration Admin provider that works within the limits of the host platform.
Under the hood, the Felix Configuration Admin service uses one or more PersistenceManagers to persist and retrieve the configuration data for your managed services. If you're curious about these implementation details you can read about them on the Felix website or you can take a look at the source code.
The configuration is OSGi is handled by the Configuration Admin Service
If you use OSGi container such as Karaf, you will remark that your configuration is independent from your bundle ($KARAF_HOME/etc) and are injected by the configuration admin service.
As was already said, Configuration Admin is your friend here. In OSGi enRoute we've a page about Configuration Admin and a sample project with lots of Configuration Admin example code.
I am trying to develop an application that can be configured by its users. I need the configuration to be done by installing/updating/stopping/uninstalling bundles. All this should be of course done dynamically during the run-time of the application.
I found a nice framework which is Apache Felix FileInstall that provides a directory in which it seems to add a bundle when you add the bundle file in the directory (update, and remove bundles similarly).
But I can see that this method does not work in my case. I need to have the bundles in the directory but to stop or even uninstall them by my application. And I want to install them when it is appropriate. This is how I am expecting the configuration of my application to be done.
Is what I am trying to achieve supported by Apache FileInstall? Am I making any wrong assumptions about this framework? What are other possible ways that would help me if Apache FileInstall is not enough? Thanks.
You don't need FileInstall for this, just use the OSGi APIs. You specifically mentioned installing, updating, stopping and uninstalling; these are supported with the following API calls respectively:
BundleContext.installBundle
Bundle.update
Bundle.stop
Bundle.uninstall
Incidentally these are exactly the same methods that are called by FileInstall to implements its directory-based bundle management.
I try to use the "Apache Felix" implementation of OSGi for my project, I launch the framework from the distributable jar (/bin /felix.jar). I have created simple example bundles to register or consume services in the registry.
I want to use a configuration management service so I installed the bundle "org.apache.felix.configadmin" felix in the framework, and then I do not know how and where to put the configuration file of another bundle, for example I want to install the bundle "org.apache.felix.http.jetty" and then I want to configure this bundle through the configAdmin, so how I rename my config file, and where to put it?
Another question, what is the difference between setting, for example, the property "org.osgi.service.http.port" of the jetty bundle using the framework properties(conf/config.properties) or configure it through the bundle of configuration admin service.
Best regards,
You probably also need the file-installer from felix for it to pick up the config files.
If you want to see a working example of this take a look at Apache Karaf. It's a OSGi Container with lots of nice preconfigured features. The config admin service works out of the box.
Normally you use the felix config admin service together with the felix fileinstall. So fileinstall takes care of the directory to be monitored for config files and hands over to config admin to make it available as configs in OSGi.
For a fully working example take a look at Apache Karaf. There you can see the configs you need for it to work together. You might also consider to simply install your own bundles into karaf as it makes managing the felix framework a lot easier.
We run Restlet 2.1 in an OSGi environment (Equinox) as bundle (ie. not as library within a bundle). The problem is that the Restlet Engine does not detect helpers (like converters) that are provided by Restlet extensions. Specifically, the EngineClassLoader#getResources() call does not return any result. The extensions are also deployed as OSGi bundles in the target platform.
Is automatic converter registration actually supposed to work within OSGi environments?
In fact, Restlet supports such feature thanks to a dedicated activator (see the Activator class in the package org.restlet.engine.internal).
This activator introspects bundles to find out the following things:
servers corresponding to registered servers
servers corresponding to registered clients
authenticators corresponding to registered clients
converters
Be aware that to use this feature, we must use the OSGi edition of Restlet since it's the only that has the MANIFEST file of the org.restlet bundle with the activator class specified. Otherwise you don't have to care about the bundle loading order...
Hope it helps you.
Thierry
Unless the Restlet-bundle explicitly imports the packages that contain the extensions (and I doubt it does, and it shouldn't), it wouldn't be able to load them, because bundles have isolated class-spaces.
A possible solution would be to provide the extensions as fragments attached to the Restlet-bundle. Thus, if you make it use the bundle-classloader (the documentation says this can be done by setting the Engines classloader), it would be able to load classes from the fragments.
Indeed it doesn't quite work for OSGi, as it depends on the ability to see the entire class space.
The way to do this in OSGi would be to use the service registry for the extensions, but that only works for OSGi aware libraries.
There is some help on the way: In the recently released OSGi 5 (Service Loader Mediator) there will be support to 'bridge' META-INF/services (I don't know if Restlet uses those, though) onto OSGi services, so 'legacy' libraries should work well within OSGi.
There is an implementation in Apache Aries called Spi-Fly. I looked at it briefly a while back. It might do the trick for you, it might not.
I have a server side application and want to embed an osgi framework into for dynamic bundle loading.
Suppose I want to expose a QuoteImpl implementing IQuote(instantiated as part of the server container bootstrap/Spring) to be used by different Bundles.
Q1. Is there a clean way of exposing server-application instances to Bundles ? (btw because of legacy it is not possible to make server code into bundle :) and donot want to make entire application osgi'ed.
Tried exposing via a service and bundle to cast into an IQuote. Not sure I am doing it well but fails with unresolved compilation problems as IQuote resides in the core app projects as opposed to the bundle project. any ideas?
Yes the way to do this is with a service. The "host" application would publish the service and the bundles inside OSGi would consume the service in the normal way.
The key to get this working is that the service API (i.e. the package containing IQuote) must be exported by the host application through the system bundle exports. You can control this by setting the org.osgi.framework.system.packages.extra property when you create the embedded OSGi framework. I wrote a blog post on this subject that should help you get started (look for the heading "Exposing Application Packages").
You state that you have compilation problems. To fix those it's necessary to know how you have structured your projects and build system.
This is how I embedded Equinox OSGi runtime in my Java class. I suppose you could do the same. https://github.com/sarxos/equinox-launcher/blob/master/src/main/java/com/github/sarxos/equinox/Launcher.java