Topics

• Topics
  • Introduction:
    • Topic no.1
      • Required Interface
    • Topic no.2
      • Mapstruct
    • Topic no.3
      • Log4j Marker Filter
    • Topic no.4
      • Custom Annotation
        • Simple Processor
        • AOP Processor
    • Topic no.5
      • Awaitility
    • Topic no.6
      • Junit-5 Examples
    • Topic no.7 - Jmeter-Dockerized
    • Topic no.8 - Vault-Example

Introduction:

This repo will be serving the base having multiple modules where concepts will be practise.

Topic no.1

Required Interface

Required Interfaces concept forwarded by 'Martin Fowler'. Explanation can be followed @ https://martinfowler.com/bliki/RequiredInterface.html

Example :

client : required-interface-client-layer
service : required-interface-service-layer

client need to use PrintService from service layer, client is already dependency of Service layer, so normally if we want to access PrintService class we need to add service as dependency and as result it would introduce cyclic dependency and will not be able to compile.

In order to make it working, we define client base interface and we implement them in service and use what we want from service.

RequiredInterface in client module and its implementation in service layer tells the whole story that how to enable client to use services from parent layer.

Topic no.2

Mapstruct

MapStruct is a code generator that greatly simplifies the implementation of mappings between Java bean types based on a convention over configuration approach.

The generated mapping code uses plain method invocations and thus is fast, type-safe and easy to understand.

Example :

Credential(username, password) -----mapping to ---->>> CredentialDto using interface CredentialMapper
for more examples explore https://github.com/mapstruct/mapstruct-examples

Topic no.3

Log4j Marker Filter

Log4j has ability to distinguish between logs and funnel out into dedicated files, this all can be achieved by using Marker filter. Module logging has implementation of Maker concepts, where various logs are funnel out to their dedicated log files. log42.xml has implementation of seperation logic.
<MarkerFilter marker="SPECIFIC" onMatch="ACCEPT" onMismatch="DENY"></MarkerFilter>

Topic no.4

Custom Annotation

Module customannotation will contain code to create custom annotation and then process with two approaches

Simple Processor

Normal Annotation processor

AOP Processor

Aspect Oriented Annotation Having @Identifier annotation on method, based on age it will be executed and when the age is below the limit it will throw exception and will not provide required data for that person.

Topic no.5

Awaitility

Awaitility is a small Java DSL for synchronizing asynchronous operations

Example :

A simple asynchronous service which increments a counter and sleep for some time before get initialized. The example is proof of concept that awaitility make the test wait until a condition is meet and then assert the output.

Topic no.6

Junit-5-Examples

Here, i will try to provide examples for

• Extension
  • Tried three extension like Parameter resolver, Exceptionhandler and postprocessor exception
  • LoggingExtensionTest is describing the test usge of all above extensions.
• Parameterized Tests

Topic no.7

Jmeter-Dockerized

Run a basic hello world Jmeter testing scenario in dockerized environment with master-slave configuration. docker-compose.yml will spawn Master docker and its slaved to run a basic jmeter scenario prepared in jmeter i.e scenario.jmx.

Jmeter-Prometheus-Grafana

Grafana : http://localhost:3000
Prometheus: http://localhost:9090
Master-Slave0-Slave1 ---(sendData)---> Prometheus

How to Run

• docker-compose --profile monitor up --build
• add prometheus datasource to Grafana (http://localhost:9090 - Access 'Browser')
• docker-compose --profile jmeter up --build -d
  Note: Ideally no profile is required but to till the writing of this note i was not able to correctly configure datasource

Topic no.8

Vault-Example

A docker vault in development mode spins up and basic credentials added via http://localhost:8200 and could be read with help of VaultTemplate class.

How to Run

http://localhost:8200
docker-compose up -d
Application can be run with env variable i.e VAULT_TOKEN=vault;VAULT_SERVER=http://localhost:8200 in run configuration