This is a tiny implementation of basic patterns for microservice architecture. It based on spring boot/web, java stack. The major communication channel is an HTTP focused on async communication(the answer is returned immediately). Common logic is provided by discovery project.
the admin service needs to ensure all stored services are alive and have a good condition/state otherwise to do something.
- healthcheck / metrics
- close operations
- init operations
The basic idea for a circuit breaker is to be a proxy between a service and its invoker.
If the service has some degradation in performance it should be disabled or terminated or restarted or whatever.\
The communication process between microservices is the most important thing.
That is why the messages should be standardized and being involved in the hierarchy.
- message hierarchy
- message builders
every service while starting to send a registration request to admin service. Also server send his properties to config interacting. It can be useful if there is more than one instance and it passes through a load balanced strategy
- service registry
admin service needs to save all coming information to persistent storage. For that, persistent file storage has been added. the common principle of this storage is classic key-value storage wherein a key is a file and values are lines of the file.
- storage listeners - reactive approach
when there is more than one service instance it is a common approach to have a strategy to return some a service instance.
The basic idea to use conflict-free replicated data types is a flavor of eventual consistency that ensures conflicts can be merged automatically to produce a value that is guaranteed to be correct/consistent.
- pncounter
- event based
- state based
- lwwregister
The Saga pattern is an architectural pattern which provides an alternative approach to big and long running ACID transactions.
It takes a business process and breaks it up into small isolated steps – each of them with its own transaction./
The overall consistency is provided by manually reverting past actions.
there are 2 types of saga:
- event based
- orchestrator based
The basic idea is to get a resource pool of workers and spread task between them.
- workers/resource pool
- resource manager
- pull task from metric
- complex command (orchestrator / dsl)
The basic idea is to collect all logs from all microservices to one place. This implementation does it through a file system.
Active-passive replication for leader/followers system