Unable to initialize system Data Source provider - wso2

Question

I am working on WSO2 EI 6.5 and i try to fix a problem.
I changed my log4j.properties to use Kafka and Log4j.
In WSO2 EI 6.5 (and since 6.3), i've got a problem with slf4f and Kafka, and that for why i changed my version of slf4j-api in my /wso2/components/plugins/ folder (1.7.21 to 1.7.12).
The problem is, when i do that or something else about slf4j (like changing the pom.xml and recompile my slf4j-api), i've got an other problem when i try to launch integrator.sh
There is the log :
[2019-06-12 11:45:36,586] [EI-Core] INFO - KafkaEventAdapterServiceDS Successfully deployed the Kafka output event adaptor service
[2019-06-12 11:45:37,314] [EI-Core] ERROR - DataSourceServiceComponent Error in intializing system data sources: Error in initializing system data sources: Error in initializing system data sources at '/Users/robyn/Desktop/wso2ei-6.5.0/conf/datasources/custom-datasources.xml' - Error in loading data source provider: org.wso2.carbon.dataservices.core.custom.datasource.CustomTabularDataSourceReader cannot be found by org.wso2.carbon.ndatasource.core_4.4.40
org.wso2.carbon.ndatasource.common.DataSourceException: Error in initializing system data sources: Error in initializing system data sources at '/Users/robyn/Desktop/wso2ei-6.5.0/conf/datasources/custom-datasources.xml' - Error in loading data source provider: org.wso2.carbon.dataservices.core.custom.datasource.CustomTabularDataSourceReader cannot be found by org.wso2.carbon.ndatasource.core_4.4.40
at org.wso2.carbon.ndatasource.core.DataSourceManager.initSystemDataSources(DataSourceManager.java:169)
at org.wso2.carbon.ndatasource.core.internal.DataSourceServiceComponent.initSystemDataSources(DataSourceServiceComponent.java:213)
at org.wso2.carbon.ndatasource.core.internal.DataSourceServiceComponent.setSecretCallbackHandlerService(DataSourceServiceComponent.java:199)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.eclipse.equinox.internal.ds.model.ComponentReference.bind(ComponentReference.java:376)
at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.bindReference(ServiceComponentProp.java:430)
at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.bind(ServiceComponentProp.java:218)
at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.build(ServiceComponentProp.java:343)
at org.eclipse.equinox.internal.ds.InstanceProcess.buildComponent(InstanceProcess.java:620)
at org.eclipse.equinox.internal.ds.InstanceProcess.buildComponents(InstanceProcess.java:197)
at org.eclipse.equinox.internal.ds.Resolver.getEligible(Resolver.java:343)
at org.eclipse.equinox.internal.ds.SCRManager.serviceChanged(SCRManager.java:222)
at org.eclipse.osgi.internal.serviceregistry.FilteredServiceListener.serviceChanged(FilteredServiceListener.java:107)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.dispatchEvent(BundleContextImpl.java:861)
at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:148)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.publishServiceEventPrivileged(ServiceRegistry.java:819)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.publishServiceEvent(ServiceRegistry.java:771)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistrationImpl.register(ServiceRegistrationImpl.java:130)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.registerService(ServiceRegistry.java:214)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.registerService(BundleContextImpl.java:433)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.registerService(BundleContextImpl.java:451)
at org.wso2.carbon.securevault.internal.SecretManagerInitializerComponent.activate(SecretManagerInitializerComponent.java:48)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.eclipse.equinox.internal.ds.model.ServiceComponent.activate(ServiceComponent.java:260)
at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.activate(ServiceComponentProp.java:146)
at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.build(ServiceComponentProp.java:345)
at org.eclipse.equinox.internal.ds.InstanceProcess.buildComponent(InstanceProcess.java:620)
at org.eclipse.equinox.internal.ds.InstanceProcess.buildComponents(InstanceProcess.java:197)
at org.eclipse.equinox.internal.ds.Resolver.buildNewlySatisfied(Resolver.java:473)
at org.eclipse.equinox.internal.ds.Resolver.enableComponents(Resolver.java:217)
at org.eclipse.equinox.internal.ds.SCRManager.performWork(SCRManager.java:816)
at org.eclipse.equinox.internal.ds.SCRManager$QueuedJob.dispatch(SCRManager.java:783)
at org.eclipse.equinox.internal.ds.WorkThread.run(WorkThread.java:89)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.wso2.carbon.ndatasource.common.DataSourceException: Error in initializing system data sources at '/Users/robyn/Desktop/wso2ei-6.5.0/conf/datasources/custom-datasources.xml' - Error in loading data source provider: org.wso2.carbon.dataservices.core.custom.datasource.CustomTabularDataSourceReader cannot be found by org.wso2.carbon.ndatasource.core_4.4.40
at org.wso2.carbon.ndatasource.core.DataSourceManager.initSystemDataSource(DataSourceManager.java:189)
at org.wso2.carbon.ndatasource.core.DataSourceManager.initSystemDataSources(DataSourceManager.java:164)
... 40 more
Caused by: org.wso2.carbon.ndatasource.common.DataSourceException: Error in loading data source provider: org.wso2.carbon.dataservices.core.custom.datasource.CustomTabularDataSourceReader cannot be found by org.wso2.carbon.ndatasource.core_4.4.40
at org.wso2.carbon.ndatasource.core.DataSourceManager.addDataSourceProviders(DataSourceManager.java:140)
at org.wso2.carbon.ndatasource.core.DataSourceManager.initSystemDataSource(DataSourceManager.java:180)
... 41 more
Caused by: java.lang.ClassNotFoundException: org.wso2.carbon.dataservices.core.custom.datasource.CustomTabularDataSourceReader cannot be found by org.wso2.carbon.ndatasource.core_4.4.40
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:501)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:421)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:412)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at org.wso2.carbon.ndatasource.core.DataSourceManager.addDataSourceProviders(DataSourceManager.java:136)
... 42 more
[2019-06-12 11:45:38,315] [EI-Core] INFO - EmbeddedRegistryService Configured Registry in 54ms
[2019-06-12 11:45:38,386] [EI-Core] INFO - RegistryCoreServiceComponent Registry Mode : READ-WRITE
[2019-06-12 11:45:38,797] [EI-Core] INFO - UserStoreMgtDSComponent Carbon UserStoreMgtDSComponent activated successfully.
[2019-06-12 11:45:49,941] [EI-Core] INFO - TaglibUriRule TLD skipped. URI: http://tiles.apache.org/tags-tiles is already defined
[2019-06-12 11:46:50,863] [EI-Core] WARN - CarbonServerManager Carbon initialization is delayed due to the following unsatisfied items:
[2019-06-12 11:46:50,867] [EI-Core] WARN - CarbonServerManager Waiting for required Deployer: UserStoreConfigurationDeployer
[2019-06-12 11:46:50,868] [EI-Core] WARN - CarbonServerManager Waiting for required OSGi Service: org.wso2.carbon.dataservices.core.internal.DSDummyService
[2019-06-12 11:46:50,868] [EI-Core] WARN - CarbonServerManager Waiting for required OSGiAxis2Service: org.wso2.carbon.sts-5.2.19
[2019-06-12 11:46:50,869] [EI-Core] WARN - CarbonServerManager Waiting for required OSGiAxis2Service: org.wso2.carbon.identity.user.store.count-5.12.387
[2019-06-12 11:46:50,869] [EI-Core] WARN - CarbonServerManager Waiting for required Module: rampart-trust-1.6.1-wso2v34
[2019-06-12 11:46:50,869] [EI-Core] WARN - CarbonServerManager Waiting for required Deployer: DataServicesDeployer
I've tried to replace all org.wso2.carbon.ndatasource libraries with older version (from 6.2.0) but nothing seems to work.
Any idea ? Thank you !

Answer 1

This comes due to the slf4j dependent OSGi bundles doesn't get activated due to the bundle resolving inconsistency which caused by the replaced slf4j jars. The recommended approach is to use Kafka jars which are compatible with the EI 6.5.0 [1].
However, if you want to use the older slf4j versions(1.7.12) you can remove the latest jar versions (slf4j.api_1.7.21, slf4j.log4j12_1.7.21) from the plugins folder and add the older jars (slf4j.api_1.7.12, slf4j.log4j12_1.7.12) to {EI_HOME}/dropins folder and restart the server. (Note that this approach is not recommended since this can be cause for inconsistencies and maintainability issues. Hence try to use approach 1 as mentioned)
[1] - https://docs.wso2.com/display/EI650/Kafka+Inbound+Protocol