Cumulocity implementing new protocol - spring

Question

I'm working on the tracker-agent and trying to add a new protocol to use with my devices. I tried to mimic what you did with the GL200 protocol, however when it reaches TrackerFactory.create(), it returns the following error:
16:05:47.912 [pool-2-thread-1] ERROR c8y.trackeragent.RequestHandler - Error handling request:
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'connectedAXTracker': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: protected java.util.List c8y.trackeragent.ConnectedTracker.fragments; nested exception is org.springframework.beans.factory.NoSuchBeanDefinition
Exception: No qualifying bean of type [c8y.trackeragent.Fragment] found for dependency [collection of c8y.trackeragent.Fragment]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {#org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1202) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:217) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:350) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:331) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at c8y.trackeragent.protocol.mapping.TrackerFactory.create(TrackerFactory.java:76) ~[classes/:na]
at c8y.trackeragent.protocol.mapping.TrackerFactory.discoverTracker(TrackerFactory.java:48) ~[classes/:na]
at c8y.trackeragent.protocol.mapping.TrackerFactory.getTracker(TrackerFactory.java:33) ~[classes/:na]
at c8y.trackeragent.RequestHandler.run(RequestHandler.java:32) ~[classes/:na]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_91]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_91]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_91]
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: protected java.util.List c8y.trackeragent.ConnectedTracker.fragments; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [c8y.trackeragent.Fragment] found for dependency [collection of c8y.trackeragent.Fragment]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {#org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:561) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
... 14 common frames omitted
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [c8y.trackeragent.Fragment] found for dependency [collection of c8y.trackeragent.Fragment]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {#org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1308) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1006) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:949) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:533) ~[spring-beans-4.1.4.RELEASE.jar:4.1.4.RELEASE]
... 16 common frames omitted
I have no knowledge of Spring, could you give me a hint?

Answer 1

I found the problem: my classes that extended the AXFragment interface (itself extending Fragment) weren't flagged as #Component.

Answer 2

Just from the stack trace this happened:
It discovered that the tracker connecting was of the type you added but when trying to instantiate the class it failed because it could not set the fragements list that is required for that class.
Every tracker protocol needs to have at least on fragment (a class implementing c8y.trackeragent.Fragment).
If you look at the GL200 implementation there is another interface GL200Fragment and then for example the parser (GL200Parser) implements that interface. It looks like you did not add any class that implements this interface.