Java Technology Lead

It is an empty interface (no field or methods). Examples of marker interface are Serializable, Cloneable and Remote interface. All these interfaces are empty interfaces. 
public interface Serializable 
{
// nothing here
}

Heap is a memory place where the objects and its instance variable are stored.
So to sum it up:
Class objects, including method code and static fields: heap.
Objects, including instance fields: heap.

The Abstract Factory Pattern
1. Provide an interface for creating families of related or dependent objects without specifying their concrete classes.
2. The Abstract Factory pattern is very similar to the Factory Method pattern. One difference between the two is that with the Abstract Factory pattern, a class delegates the responsibility of object instantiation to another object via composition whereas the Factory Method pattern uses inheritance and relies on a subclass to handle the desired object instantiation.
3. Actually, the delegated object frequently uses factory methods to perform the instantiation!

Factory pattern
1. Factory patterns are examples of creational patterns
2. Creational patterns abstract the object instantiation process. They hide how objects are created and help make the overall system independent of how its objects are created and composed.
3. Class creational patterns focus on the use of inheritance to decide the object to be instantiated Factory Method
4. Object creational patterns focus on the delegation of the instantiation to another object Abstract Factory

Basic Kubernetes architecture exists in two parts: the control plane and the nodes or compute machines. Each node could be either a physical or virtual machine and is its own Linux environment. Every node also runs pods, which are composed of containers. Kubernetes architecture components or K8s components include the Kubernetes control plane and the nodes in the cluster. The control plane or master machine components include the Kubernetes API server, Kubernetes scheduler, Kubernetes controller manager, and etcd. Kubernetes node components include a container runtime engine or docker, a Kubelet service, and a Kubernetes proxy service.

Kafka Streams is a client library for building applications and microservices, where the input and output data are stored in an Apache Kafka® cluster. It combines the simplicity of writing and deploying standard Java and Scala applications on the client side with the benefits of Kafka’s server-side cluster technology.

An API Gateway is the single point of entry for any microservice call.
It can work as a proxy service to route a request to the concerned microservice.
It can aggregate the results to send back to the consumer.
This solution can create a fine-grained API for each specific type of client.
It can also convert the protocol request and respond.
It can also offload the authentication/authorization responsibility of the microservice.