Sonar Java Injection

Rules not assigned by default, but very useful:

 - https://rules.sonarsource.com/java/RSPEC-3749
  Members of Spring components should be injected

- https://rules.sonarsource.com/java/RSPEC-4288
  Spring components should use constructor injection
 

HikariCP lifecycle

 Buen post que explica como las conexiones de HikariCP son obtenidos y los posibles mensajes de error que son tirados.

https://medium.com/@rajchandak1993/understanding-hikaricps-connection-pooling-behaviour-467c5a1a1506

https://github.com/brettwooldridge/HikariCP/wiki/Bad-Behavior:-Handling-Database-Down

 

Algorithms and Data Structures for Massive Datasets

Technical Reviewer:

Dzejla Medjedovic, Emin Tahirovic, and Ines Dedovic
MEAP began July 2020 Publication in January 2022 (estimated)
ISBN 9781617298035 325 pages (estimated) printed in black & white

https://www.manning.com/books/algorithms-and-data-structures-for-massive-datasets

netcat - nc

netcat
ncat
nc

-n : skip DNS lookups
-u : Use of UDP mode (instead of TCP)
-v : Extensive output
-w : timeout (seconds)
-z : Port scanner mode (zero I/O mode); only listening services are scanned (no data is sent)

Scan port 123 for NTP:
nc -z -v -u 0.us.pool.ntp.org 123


scan ports:
nc -w 2 -z 192.168.10.1 1-1024

nc -v -n 8.8.8.8 1-1000

Practical C++ Design

Technical Reviewer:

© 2022
Practical C++ Design
From Programming to Architecture
Authors: Singer, Adam B.

https://www.apress.com/us/book/9781484274064

Functional Design and Architecture

Technical Reviewer:

Alexander Granin
MEAP began July 2021 Publication in Early 2022 (estimated)
ISBN 9781617299612 575 pages (estimated)

https://www.manning.com/books/functional-design-and-architecture

Mutually Orthogonal Latin order 10

 A predecessor to Sudoku:

Emi Kasai bases on a Mutually Orthogonal Latin squares (MOLS)

https://en.wikipedia.org/wiki/Mutually_orthogonal_Latin_squares#Euler's_conjecture_and_disproof

http://martin-gardner.org/SciAm12.html

Devwebcl's Madness

 Inspired by Scientific American's article.

Miller's Madness

After 33 years:

COMPUTER RECREATIONS
A. K. Dewdney
Scientific American
Vol. 258, No. 5 (MAY 1988), pp. 118-121 (4 pages)

https://www.jstor.org/stable/24989094

AWS Serverless Data Lake Framework

SDLF is a peculiar framework developed by AWS as a Data Lake using their services.

It is interesting how it creates two pipelines where the data is parsed (reduced), process as a big ETL, where finally can be exploited by BI products.

• AWS Glue
• S3
• Lambda
  

https://sdlf.readthedocs.io/en/latest/index.html

https://sdlf.workshop.aws/en/

https://github.com/awslabs/aws-serverless-data-lake-framework

Minimize Costs in Cloud-Based Microservices

Beta tester:

https://www.manning.com/bundles/minimize-costs-in-cloud-based-microservices-ser

Converting Legacy Applications to Cloud Native in Kubernetes

 Beta tester:

https://www.manning.com/liveproject/converting-legacy-applications-to-cloud-native-in-kubernetes

Spring in Action, Sixth Edition

Beta tester:

+ Technical Proofer. (September 2021)

Craig Walls
MEAP began May 2020 Publication in Early 2022 (estimated)
ISBN 9781617297571 520 pages (estimated)

https://www.manning.com/books/spring-in-action-sixth-edition

1. EKS Diagrams

Cluster > Node > Pod > Container

There are two types of nodes:

• A Control-plane-node type, which makes up the Control Plane, acts as the “brains” of the cluster.
  
  

• A Worker-node type, which makes up the Data Plane, runs the actual container images (via pods).
  
  

Pod A thin wrapper around one or more containers

DaemonSet Implements a single instance of a pod on a worker node

Deployment Details how to roll out (or roll back) across versions of your application

ReplicaSet Ensures a defined number of pods are always running

Job Ensures a pod properly runs to completion

Service Maps a fixed IP address to a logical group of pods

Label Key/Value pairs used for association and filtering

Cluster > Node > Pod > Container

A container runs typically as a single Unix process

EKS simple way

The simplest way to generate an AWS EKS

- install: awscli, eksctl, kubectl

 1.
eksctl create cluster -f cluster.yml
(it takes several minutes, 20 mins?)

cluster.yml:

	apiVersion: eksctl.io/v1alpha5
	kind: ClusterConfig
	metadata:
	name: my-kube-config
	region: us-west-1
	nodeGroups:
	- name: node-group-1
	desiredCapacity: 2
	instanceType: t2.micro
	ssh:
	- name: node-group-2
	desiredCapacity: 1
	instanceType: t2.micro
	ssh:

view raw cluster.yml hosted with ❤ by GitHub

2.
eksctl delete cluster --region=us-west-1 --name=my-kube-config


3.
eksctl get cluster

4.
kubectl config view

5.
//mandatory? (yep!)
aws eks update-kubeconfig --name <cluster-name>
aws eks update-kubeconfig --name cobroqr-eks-RCXW8qM5


6.
kubectl create deployment hello-node --image=k8s.gcr.io/echoserver:1.4

7.
kubectl get deployment

8.
kubectl get pods

9.
kubectl expose deployment hello-node --type=LoadBalancer --port=8080

10.
kubectl get services
(aca deberia aparecer el service nuevo agregado arriba en "expose" como LoadBalancer).
aca sale tb el EXTERNAL-IP para poder probar

11.
kubectl exec --stdin --tty hello-node-7567d9fdc9-6lbx4 -- /bin/bash
(del kubectl get pods)


12.
kubectl delete deployment --all
  deployment.apps "books-node" deleted
  deployment.apps "hello-node" deleted


13.
eksctl delete cluster --name <cluster-name>
eksctl delete cluster --name my-kube-config.us-west-1.eksctl.io



---------------------------

more examples:

6.
kubectl create deployment books-node --image=091501399925.dkr.ecr.us-west-1.amazonaws.com/ecr-eks-sandbox:latest

(al ver get deployment y get pods, veo que hay 1 pod por deploy...

9.
kubectl expose deployment books-node --type=LoadBalancer --port=8080


curl http://af760c2d8e8ff40608558465fa4a4a4e-710530633.us-west-1.elb.amazonaws.com:8080/books
(se demora en publicar)


12.
kubectl delete deployment --all

cognado, da

 1. adj. Gram. Emparentado morfológicamente.

 

En Portugues es Cognato, y tenemos muchos cognados falsos

The Checker Framework

 A peculiar static code analyzer.

	import org.checkerframework.checker.nullness.qual.*;
	import org.checkerframework.checker.tainting.qual.*;
	/*
	https://checkerframework.org/manual/#installation
	javac.bat -processor TaintingChecker CheckerSimplePoc.java
	TaintingChecker
	FormatterChecker
	NullnessChecker
	UnitsChecker
	RegexChecker
	*/
	public class CheckerSimplePoc {
	private static final String ERROR_MESSAGE_HPAM_NOT_EXISTS = "No existe ningun registro en hpamMarca con id %s";
	public static void main( @Tainted String[] args) {
	@PolyTainted String aa = "xxxxxx";
	String hola = String.format(ERROR_MESSAGE_HPAM_NOT_EXISTS, args[0]);
	String hola2 = String.format(ERROR_MESSAGE_HPAM_NOT_EXISTS + aa);
	System.out.format( aa );
	System.out.format( args[0] );
	System.out.println( hola );
	System.out.println( String.format("%y", 7) );
	// ------------------------
	System.out.format(
	args[0] + " not valid. HINT: %s",
	args[1]
	);
	}
	public void metodo(@Tainted String s) {
	String hola = String.format(ERROR_MESSAGE_HPAM_NOT_EXISTS, s);
	System.out.format( ERROR_MESSAGE_HPAM_NOT_EXISTS, s );
	//System.out.println( String.format("%y", 7) );
	}
	}

view raw CheckerSimplePoc.java hosted with ❤ by GitHub

Develop Secure Java Applications to Prevent Website Attacks

 Technical proofed/reviewed:

https://www.manning.com/bundles/develop-secure-java-applications-to-prevent-website-attacks

Solution to double partition Alphametics

“Solution to double partition Alphametics”, Knuth Donald, The Art of Computer Programming, Pre-Fascicle 2b, Generating All Permutations, Addison-Wesley, 12 June 2004, p. 42. http://www-cs-faculty.stanford.edu/~knuth/taocp.html#vol4

Bcrypt Spring Security

From https://github.com/devwebcl/spring-samples

This simple sample to hash password using blowfish2a compatible with Postgres pgcrypto https://www.postgresql.org/docs/9.3/static/pgcrypto.html

It uses sample from http://docs.spring.io/spring-security/site/docs/current/apidocs/org/springframework/security/crypto/bcrypt/BCrypt.html

update: https://docs.spring.io/spring-security/site/docs/current/api/org/springframework/security/crypto/bcrypt/BCrypt.html

 

 

	package cl.devweb.spring.security.hashing.blowfish;
	import org.springframework.security.crypto.bcrypt.BCrypt;
	/*
	* This simple sample to hash password using blowfish2a compatible with
	* Postgres pgcrypto https://www.postgresql.org/docs/9.3/static/pgcrypto.html
	*
	*/
	public class SpringSecurityTest {
	public static void main(String[] args) {
	String salt = BCrypt.gensalt(6);
	System.out.println("salt:" + salt );
	String password = "holamundo";
	String stored_hash = "$2a$06$Rja8BGNHYDAQmWdDnaPZZeZDe1PzD8AUrwwyWurJ7t7qk7SDAjjyy";
	// sample from http://docs.spring.io/spring-security/site/docs/current/apidocs/org/springframework/security/crypto/bcrypt/BCrypt.html
	String hashed = BCrypt.hashpw(password, stored_hash);
	System.out.println("hashed-pwd:" + hashed );
	if (BCrypt.checkpw(password, stored_hash)) {
	System.out.println("It matches");
	} else {
	System.out.println("It does NOT match");
	}
	}
	}

view raw SpringSecurityTest .java hosted with ❤ by GitHub

Apócope

En gramática, una apócope (del griego apokopé < apokopto, "cortar") es un metaplasmo donde se produce la pérdida o desaparición de uno o varios fonemas o sílabas al final de algunas palabras. Cuando la pérdida se produce al principio de la palabra se denomina aféresis, y si la pérdida tiene lugar en medio de la palabra se llama síncopa. Es una figura de dicción según la preceptiva tradicional. 

 

https://es.wikipedia.org/wiki/Ap%C3%B3cope

Swagger to PDF/HTML5

     Pasos swagger:


    We need to have installed the following tools: swagger2markup and asciidoctor

• brew install asciidoctor
• brew install swagger2markup-cli    

1.     get swagger.json with springboot up&running:
       http://127.0.0.1:8080/v2/api-docs
2.     copy swagger.json
3.     mkdir adocs
4.     swagger2markup convert -i swagger.json -d adocs
5.     modify overview.adoc (title =)
6.     asciidoctor index.adoc
7.     asciidoctor-pdf index.adoc

    $  cat index.adoc
    :doctype: book
    :toc: left
    :toclevels: 3
    :numbered:
    :hardbreaks:
    :sectlinks:
    :sectanchors:

    include::./overview.adoc[]
    include::./paths.adoc[]
    include::./security.adoc[]
    include::./definitions.adoc[]

ICMP - Internet Control Message Protocol

https://stackoverflow.com/questions/21981796/cannot-ping-aws-ec2-instance

Add a new EC2 security group inbound rule:

• Type: Custom ICMP rule
• Protocol: Echo Request
• Port: N/A
• Source: your choice (I would select Anywhere to be able to ping from any machine)

The related ping utility is implemented using the ICMP echo request and echo reply messages. 

 

https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol

Function: Send ICMP ECHO_REQUEST to network hosts

Syntax: ping [-aAbBdDfhLnOqrRUvV6] [-c count] [-F...

 

Create an Open Banking App Using OpenAPIs and Spring Boot

Technical proofed/reviewed:

 

https://www.manning.com/liveproject/create-an-open-banking-app-using-openapis-and-spring-boot

Good Java interface design

1.  AutoCloseable
2.  JpaRepository, CrudRepository and PagingAndSortingRepository.
   

Java Copy Constructor

Sometimes we need to clone an object in Java, but not a reference (a junior developer may use). There are several ways to achieve this task; however, I recommend to use a copy-constructor (that comes from C++) and, in particular, using @Builder from Lombok (to avoid boilerplate code))

 

	package cl.devweb.constructor;
	public class Cliente implements Cloneable {
	int rut;
	String nombre;
	Cliente(int rut, String nombre) {
	this.rut = rut;
	this.nombre = nombre;
	}
	// copy constructor
	Cliente(Cliente c) {
	System.out.println("Copy constructor");
	rut = c.rut;
	nombre = c.nombre;
	}
	public Object clone() throws CloneNotSupportedException {
	return super.clone();
	}
	public int getRut() {
	return rut;
	}
	public void setRut(int rut) {
	this.rut = rut;
	}
	public String getNombre() {
	return nombre;
	}
	public void setNombre(String nombre) {
	this.nombre = nombre;
	}
	}

view raw Cliente.java hosted with ❤ by GitHub

	package cl.devweb.constructor;
	public class ClienteClonePoc {
	public static void main(String[] args) {
	try {
	Cliente cliente1 = new Cliente(1, "joe");
	Cliente cliente2 = (Cliente) cliente1.clone();
	Cliente cliente3 = new Cliente(cliente1);
	Cliente cliente4 = cliente1;
	cliente1.setRut(7);
	cliente1.setNombre("john");
	System.out.println("cliente1: " + cliente1.getRut() + " " + cliente1.getNombre());
	System.out.println("cliente2: " + cliente2.getRut() + " " + cliente2.getNombre());
	System.out.println("cliente3: " + cliente3.getRut() + " " + cliente3.getNombre());
	System.out.println("cliente4: " + cliente4.getRut() + " " + cliente4.getNombre());
	} catch (CloneNotSupportedException c) {
	c.printStackTrace();
	}
	}
	}

view raw ClienteClonePoc.java hosted with ❤ by GitHub

	package cl.devweb.constructor;
	public class CopyConstructorPocLombok {
	public static void main(String[] args) {
	Premium premium1 = new Premium("pi", 3.14);
	Premium premium2 = premium1.toBuilder().build(); //copy constructor
	Premium premium3 = premium1;
	premium1.setNameOption("e");
	premium1.setPremiumValue(2.718);
	System.out.println("premium1: " + premium1.getNameOption() + " " + premium1.getPremiumValue());
	System.out.println("premium2: " + premium2.getNameOption() + " " + premium2.getPremiumValue());
	System.out.println("premium3: " + premium3.getNameOption() + " " + premium3.getPremiumValue());
	}
	}

view raw CopyConstructorPocLombok.java hosted with ❤ by GitHub

	package cl.devweb.constructor;
	import com.fasterxml.jackson.annotation.JsonAlias;
	import lombok.AllArgsConstructor;
	import lombok.Builder;
	import lombok.Getter;
	import lombok.NoArgsConstructor;
	import lombok.Setter;
	@Builder(toBuilder=true)
	@NoArgsConstructor
	@AllArgsConstructor
	@Getter
	@Setter
	public class Premium {
	@JsonAlias("nombreOpcion")
	private String nameOption;
	@JsonAlias("valor")
	private double premiumValue;
	}

view raw Premium.java hosted with ❤ by GitHub