Hi,
I am evaluating Californium for usage inside an OSGi application. I stumbled across several issues I would like to discuss:
1.
Inconsistent providing of OSGi meta-data
Some bundles provide proper OSGi meta-data, some not. IMHO all provided bundles should provide proper OSGi meta-data
californium-core-2.0.0-M3 – no OSGi meta-data
californium-proxy-2.0.0-M3 – no OSGi meta-data
element-connector-2.0.0-M3 –OSGi meta-data provided
scandium-2.0.0-M3 – OSGi meta-data provided
IMHO also core and proxy should provide proper OSGi meta-data
2.
Californium bundles not available for installation in Eclipse
To include Californium in an OSGi bundle, it needs to be downloaded from Maven Central and manually included in the target platform. I’m not sure how good it would work with Bndtools, as they have a different repository approach. But for Eclipse PDE this is
not very elegant. For this the Californium bundles should be provided via p2 Update Site. Of course that also means that all projects are provided with proper OSGi information.
3.
californium-osgi not modular
That bundle is not really modular in the sense of OSGi. It contains the contents of core and element-connector aswell as the OSGi extension. element-connector already provides OSGi meta-data. core would need the OSGi meta-data as said in 1. Then it should be
possible to put things together on the bundle level, not putting things together in one big bundle. But I’m not sure if there are some Classloader operations inside that would avoid the clear bundle separation.
4.
Netty dependency (almost) nowhere mentioned
I nowhere found Netty being mentioned as a dependency. Well it is mentioned in the MANIFEST of element-connector. Without the io.netty bundles in place, californium-osgi is not starting. If I follow the Hands-on tutorial Netty is now mentioned and not needed
to start the server. So I wonder if io.netty is really required or an optional dependency.
5.
ManagedServer not started automatically
californium-osgi contains a ManagedServer, which is a managed service that can be configured via ConfigurationAdmin and provides the white-board-pattern for registering Resources dynamically. A good idea so far, but the service is not registered automatically
and therefore the server is not started. Users need to know that they have to do this manually and of course also how to do this.
IMHO the ManagedServer should be an Immediate Component, with a required configuration. This would enable to create multiple servers in one runtime with different configurations. Not sure if that makes sense, otherwise it should be a singleton service. It should
have a service reference to EndPointFactory. DYNAMIC GREEDY to support dynamic exchange of it. Does that make sense?
I also noticed that there is no way to start the server. In its current state I need to create the ManagedServer instance and call update(null) to start it. It therefore requires a configuration to be set although it says it can start with a default configuration.
This is also not very consistent.
For the last point I think I can try to provide something via PR. Need to test what I am able to do. But for the other topics I’m unsure. The first point looks like
it could be solved easily by updating the pom.xml. The second is a bit more complicated, not sure if Eclipse Bundle Recipes could help here. 3. is dependent on whether core is doing some Classloader stuff or not, otherwise also a pom.xml point. And 4. is more
a question in first place. If it is optional it is also a pom.xml topic.
Would be great if I could get some response on this. As far as it is possible for me, I would be also glad if I could help. Actually I’m even planning to write a
small blog post about using Californium in OSGi, to give people some advice.
Additionally I have another question. When is the planned release date of 2.0.0? I see and test currently with a 2.0.0-M3. The Eclipse project page doesn’t mention
a 2.0.0 release with a release date. Is M3 already so close to the release that the needed OSGi changes can’t be added anymore?
Mit freundlichen Grüßen / Best regards
Dirk Fauth
Automotive Service Solutions, ESI application (AA-AS/EIS2-EU)
Robert Bosch GmbH | Postfach 11 29 | 73201 Plochingen |
GERMANY |
www.bosch.com
Tel. +49(7153)666-1155 |
Dirk.Fauth@xxxxxxxxxxxx
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