I have a system declaring services "the old way", using activator methods.
Now I'm writing a new bundle using Declarative Services.
Is it possible to reference a service that is not published using the Declarative Services technique in my new bundle?
There is no "the old way" to publish you services into OSGi Service Registry. There is only one way with BundleContext.registerService(). You can do it manually from you activator, or Declarative Services / Blueprint engines can do it for you.
In your DS descriptor you just define references to services that are available in Service Registry.
Yes, it is possible. When you reference a service from a DS component, you don't need to worry about that service's internal implementation.
The other service may be another DS component, or it may be a Spring-DM component, or it may be published with explicit calls to the OSGi APIs. You don't care. It's just a service.
Related
I have a non-blueprint bundle which provides a service via Declarative Service annotations.
I have another bundle, using blueprint, which contains a optional reference for this service and then injects this reference into a number of declared beans.
Starting up both within a Karaf container, the service is registered and the blueprint bundle can access it and use as intended. The configuration for the service providing bundle can be updated, and it is unbound and rebound again to the blueprint bundle which is perfect.
However, when the service providing bundle is restarted, or updated, the service is unbound but never rebound to the using bundle, so that the proxy object held by the blueprint reference never resolves to the service reference.
Sometimes restarting the blueprint bundle will fix this, but usually it requires a full framework restart to get it working again.
I do not get the same behavior when a non-blueprint bean is consuming the service via declarative services.
Has anyone had any similar issues with using a mix of DS and blueprint to provide/consume services?
Blueprint is not dynamic. It has a "damping" proxy which tries to wallpaper over service dynamism but does not always provide what is needed. In general, I would always use DS over Blueprint.
I am considering writing a new set of applications using OSGi, but they will need to interact heavily with existing non-OSGi applications.
To clarify, the new applications will need to call into existing non-OSGi code bases maintained by other teams (usually propriety services of varying protocols), and new non-OSGi applications will need to call the new OSGi services.
I am not seeing much documentation for how to do this.
Can someone please point me to the correct steps
It sounds like you want to embed OSGi into a larger application. A good starting point for this is a blog post I wrote some time ago: http://njbartlett.name/2011/07/03/embedding-osgi.html
The trick to creating visibility between OSGi bundles and the objects "outside" OSGi is to publish and/or consume services using the system bundle's BundleContext. The embedding code must be aware of the objects from the outer application that you want to make visible into OSGi, and it should publish them as services. Be aware that you need to export the service interface packages via the system bundle exports -- how to do this is described in the blog post.
OSGi services are only for communications inside the same JVM process. So I guess you want to communicate between processes. In this case you have all the usual remoting protocols like SOAP, Rest, RMI. On the OSGi side you can bridge from OSGi services to offering SOAP or REST endpoints using Distributed OSGi (DOSGi).
I’m currently “struggling” with OSGi services, or to be more specific, with the wiring between the services. I’m aware of the basics of DS, SCR and the general strategies for a component instance to acquire services. Anyway, here is my problem:
Following DS, components declare e.g. their provided and consumed services in a XML-file. In my case, I’m interested in the “consumed/referenced” services of a particular component (which are declared by the “Reference” tag in the component’s XML-file).
E.g. consider a running OSGi-application: a bunch of bundles collaborating with each other based on services (DS). Now, I want to pick a particular bundle and query all its references to the services it (may) consume - no matter if these services are currently available or not.
Referring to Apache Felix GoGo shell commands, like inspect requirements *, I do get information about the imported packages etc. but not a complete overview about the consumed services (-> both currently consumed services and services the component is waiting for).
I’ve read about the Framework API which provides insight in the registration, modification and deregistration of service but apparently, it does not provide the information about what services bundles are waiting for. Following the OSGi core specification, this could be achieved by a Listener Hook.
Isn’t there a way, where I just can query e.g. the SCR to get all referenced services of a specific bundle? Obviously, the SCR is supposed to read the bundle’s Service-Component-XML-file and to “register” some kind of “Service Tracker” to track the consumed/referenced services – hence the information of a bundle’s consumed/referenced services should somehow be available, shouldn’t it?
It would be great if you could help me with this.
Thanks,
Don
Checkout xray, http://softwaresimplexity.blogspot.com/2012/07/xray-again.html, from Peter Kriens.
I am trying to brand a Apache Felix web console, but I am not able to find resource for the same. As per Apache Felix website,
Branding for the Web Console can be provided in two ways: By registering a BrandingPlugin service or by providing a branding properties files. The Web Console uses the branding from the BrandingPlugin service registered with the highest ranking.
But I am not understanding how to register a BrandingPlugin service? What and Jar files should I put? Is there any guidance or tutorial available for the same? If yes, can you guide me in this?
Since I am totaly getting confused with Apache Felix's website, since those documents are not clear on this.
You may find it helpful to do some background reading on OSGi services. OSGi provides a service registry, and most interactions in an OSGi environment are handled by registering and consuming services. It doesn't matter what jar file you put the service in; the only thing that matters is the interface name its registered under.
You can register services in lots of ways; programmatically from a BundleActivator, using Declarative Services (also known as SCR), and using Blueprint are some of the most popular patterns. Which one is easiest for you depends on how you're building your jars and what other OSGi facilities you're using. If you've already got an Activator the programmatic route may be the quickest way to get started; if you're using the Maven bundle plugin you may find SCR annotations easiest.
What you'll need to do is include an implementation of the 'BrandingPlugin' interface in a jar which gets started by your OSGi runtime, and register that implementation as an OSGi service. Once you've done this you should see that the Felix console discovers your BrandingPlugin implementation and uses it.
I am at the moment creating a matrix which is showing how far Knopflerfish, Equinox and Felix are OSGi 4.2 compliant.
So far I looked at the Knopflerfish documentation (Link 1, Link 2) to get an idea of how much of the Core and Compendium specs are actually implemented.
The core specification seems to be fully implemented, although there are some inconsistent statements about the Security Layer and the Declarative Services.
What makes me wonder is how much of all the Compendium specs are implemented:
Remote Services
Log Service
Http Service
Device Access
Configuration Admin Service
Metatype Service
Preferences Service
User Admin Service
Wire Admin Service
IO Connector Service
Initial Provisioning
UPnP Device Service
Declarative Services
Event Admin Service
Deployment Admin
Auto Configuration
Application Admin
DMT Admin Service
Monitor Admin Service
Foreign Application Access
Blueprint Container
Tracker
XML Parser Service
Position
Measurement and State
Execution Environment
To find out more I downloaded (Download page) the source code of Knopflerfish and had a look at it. It looks like some parts of the spec are implemented through the "original" framework provided by the OSGi Alliance (org.osgi.*).
One example is the UPnP package:
alt text http://img6.imageshack.us/img6/5853/screenshot20100403at212.png
Does this mean that missing parts which are not directly implemented by Knopflerfish are added through the "original" OSGi framework?
And does this also apply to other frameworks like Felix or Equinox?
Most of the OSGi specifications define interface classes for services. You can download these classes together with the specification directly from the OSGi Alliance's website.
Implementations such as Knopflerfish must provide the underlying functionalities, e.g. the actual implementation for the UPnP Service Admin you mentioned in your example. Some of the interface classes also provide interfaces that must be implemented by the developer of a user service, e.g. a BundleActivator.
All frameworks that claim to be OSGi compliant must provide implementations for these interfaces. There is no "original" OSGi framework (well, beside of the reference implementation, of course). The interfaces do not provide implementations.