However, it may not seem sensible to do this. I can not ask the brand new developers why it actually was done this means, they’re not right here more. It project’s facts could only be told through its Git history.

Lessons learned upgrading Spring season Investigation Other people

We believe we’re playing with Springtime Investigation Rest completely wrong, wrongly blend WebMVC axioms. Whenever we hadn’t done this right away, anything would have focus on far convenient.

Our company is today carried out with the fresh Springtime Data Other people migration. It’s time to move onto our very own next Spring season component, Spring season Kafka.

Springtime Kafka

Springtime Kafka, or rather Spring for Apache Kafka , is an excellent treatment for use Kafka on your Springtime ideas. It gives simple-to-use themes for sending messages and you will regular Springtime annotations to have taking messages.

Configuring the fresh new customers

step step 1 [ERROR] coffee.lang.IllegalStateException: Don't stream ApplicationContext 2 3 Brought about by: org.springframework.beans.factory.BeanCreationException: Error doing bean with label 'consumerFactory' outlined in group path funding [ de / software / config / KafkaConsumerConfig . class ]: 4 5 Caused by: java . lang . NullPointerException six at java . legs / java . util . concurrent . ConcurrentHashMap . putVal ( ConcurrentHashMap . java: 1011 ) eight at java . base / java . util . concurrent . ConcurrentHashMap . init >( ConcurrentHashMap . java: 852 ) 8 at org . springframework . kafka . key . DefaultKafkaConsumerFactory . init >( DefaultKafkaConsumerFactory . java: 125 ) 9 at org . springframework . kafka . core . DefaultKafkaConsumerFactory . init >( DefaultKafkaConsumerFactory . java: 98 ) 10 at de . app . config . KafkaConsumerConfig . consumerFactory ( AbstractKafkaConsumerConfig . java: 120 ) 

It turns out, we had been configuring the consumerConfigs bean and setting null values in its properties. The following change from HashMap to ConcurrentHashMap means we can no longer configure null values. We refactored our code and now tests are green. Easy-peasy.

Kafka texts that have JsonFilter



1 [ERROR] org .apache .kafka mon .mistakes .SerializationException : Is 't serialize research [Enjoy [payload=MyClass(Id=201000000041600097, . ] having material [my-topic] 2 3 Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Don't eliminate PropertyFilter having id ‘myclassFilter' ; no FilterProvider configured (because of site chain: de .decide to try .Enjoy [ "payload" Noruega mujeres ] ) 4 during the com .fasterxml .jackson .databind .exc .InvalidDefinitionException .out-of (InvalidDefinitionException .java : 77 ) 



Some of our Java Beans use ato manipulate the serialization and deserialization. This requires a propertyFilter to be configured on the ObjectMapper.

Spring for Apache Kafka made a change to the JsonSerializer , introducing an ObjectWriter . When the ObjectWriter instance is created, the ObjectMapper configuration is copied, not referenced. Our test case was re-configuring the ObjectMapper with the appropriate propertyFilter after the ObjectWriter instance was created. Hence, the ObjectWriter didn't know anything about the propertyFilter (since the configuration was already copied). After some refactoring, changing how we create and configure the JsonSerializer , our test cases were green.

Running our build $ mvn clean verify finally resulted in a green build. Everything is working as it should. We pushed our changes to Bitbucket and everything built like a charm.



Instruction learned upgrading Springtime Kafka




Lessons read throughout the Spring Boot revise



Spring and Spring Boot do a great job documenting their releases, their release notes are well maintained. That being said, upgrading was challenging, it took quite a while before everything was working again. A big part of that is on us, for not following best practices, guidelines, etc. A lot of this code was written when the team was just starting out with Spring and Spring Boot. Code evolves over time, without refactoring and applying those latest practices. Eventually that catches up with you, but we use this as a learning experience and improved things. Our test cases are now significantly better, and we'll keep a closer eye on them moving forward.