Investigate Spring or AsjectJ oriented annotation of the code - an AOP design pattern

 Problem description + sizing

• There is a perception (probably accurate) that there is a lot of code that was written within each component on top of EELF that could be factored out and turned into a common wrapper on top of EELF (or perhaps something added to EELF) and thus reduce the code base
• We want to be able to add functionality to logging without modifying each component, such as the ability to send certain messages over a more near-realtime mechanism such as a message bus; this could be done in a wrapper or in an additional appender
• We want to be able to easily support future changes such as new log message formats without changing all of the components; to at least some extent we already have this in slf4j/log4j/logback
• To the extent possible, adding logging to infrastructure would eliminate the need to have every developer concerned with correct logging; this could help especially in the area of inbound API calls (Jetty is used in all of the components except MSO which uses JBoss)
• Some desire to have format validation performed at runtime, flagging an error if the format of a particular MDC did not meet the specification
• It would be nice to verify that X-ONAP-Request-ID is being passed in and picked up where required; building this as an annotation would allow developers to put an annotation on a method that enforces that X-ONAP-Request-ID came in
• Need a migration strategy
• Story for spring wrapper or plain wrapper

 Tasks

• Audit of the code (start with AAI abstract logger) - Logger references in babel, data-router, gizmo, model-loader, rest-client, router-core, search-data-service, sparky-be  (not resources, traversal)
• Prototype changes in the aspect formula to change logging injection
• Transition plan for moving all or part of the code to the new format
• Audit of spring use in each project

 Out of scope

DCAE is currently being migrated into OOM - we can push this work until later in R2

https://jira.onap.org/browse/OOM-565

https://jira.onap.org/browse/OOM-508

https://jira.onap.org/browse/LOG-48

Analysis 

https://wiki.onap.org/display/DW/LOG+Meeting+Minutes+2017-11-07

• AOP annotation support for Logging - check for existing code and raise (custom EELF annotations on top of Spring ?)

• FYI so had a classloading conflict because of two different spring versions https://gerrit.onap.org/r/#/c/23919/ for -------SO-208------
• Look also at zipkin distributed tracing via spring config and backend docker container
  https://github.com/openzipkin/brave/tree/master/spring-beans
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