Strange Patterns

05 December 2020

Posix Threads C11

simple example of Posix threads in C11, which doesn't have impl in gcc/clang. Remember to use -pthread as argument.

03 December 2020

Beginning C 6th edition

I am proud to participate as co-author in Beginning C - From Beginner to Pro, 6th Edition, press 2020.

https://www.apress.com/de/book/9781484259757

Beginning C

From Beginner to Pro - 6th Edition

Authors: Gonzalez-Morris, German, Horton, Ivor
© 2020

30 November 2020

05 November 2020

La apofenia (del griego ἀπό, apó, "separar, alejar", y φαίνειν, phaínein, "aparecer, manifestar(se) como fenómeno, fantasía") es la experiencia que consiste en ver patrones, conexiones o ambos en sucesos aleatorios o en datos sin sentido.

Este término tiene acepciones diferentes en los ámbitos de la psicología y de la estadística, donde también suele utilizarse.^{[cita requerida]}

^{https://es.wikipedia.org/wiki/Apofenia}

Estadística

En estadística, la apofenia suele estar relacionada con un error de tipo I, que puede llevar a conclusiones falsas en una investigación. La probabilidad de encontrar una asociación espuria o casual entre dos variables, y creer erróneamente que se ha encontrado una asociación real, se incrementa cuando en lugar de aplicar el método científico se realiza el hackeo estadístico de una base de datos (P-hacking). Esta mala práctica consiste en jugar con una base de datos y relacionar la variable dependiente con todas las posibles variables independientes hasta encontrar una asociación estadísticamente significativa, sin haber establecido previamente un marco conceptual y una hipótesis de investigación que justifiquen por qué se van a estudiar estas relaciones.² La publicación de estos resultados en revistas científicas es una de las causas de la pérdida de credibilidad y reproducibilidad de la ciencia, lo que ha llevado a muchos científicos a realizar manifiestos de alerta.³

30 October 2020

Sofisma

Del lat. sophisma, y este del gr. σόφισμα sóphisma.

1. m. Razón o argumento falso con apariencia de verdad.

23 October 2020

Java SIGBUS

Core dump of a lack of space at /tmp

Aborted (core dumped)
#
# https://github.com/AdoptOpenJDK/openjdk-support/issues
# If you would like to submit a bug report, please visit:"
#
# SIGBUS (0x7) at pc=0x00007f1240764eac, pid=6, tid=48#
# JRE version: OpenJDK Runtime Environment AdoptOpenJDK (11.0.8+10) (build 11.0.8+10)
# Java VM: OpenJDK 64-Bit Server VM AdoptOpenJDK (11.0.8+10, mixed mode, tiered, compressed oops, serial gc, linux-amd64)# C [libc.so.6+0x18eeac]
# Problematic frame:
#
# Core dump will be written. Default location: /usr/app/core.6
#
# An error report file with more information is saved as:
# /usr/app/hs_err_pid6.log
#
# A fatal error has been detected by the Java Runtime Environment:
#

it is interesting that docker also has shared memory device configuration /dev/shm
through shm_size

https://efod.se/java-sigbus/

https://confluence.atlassian.com/confkb/java-vm-dies-with-sigbus-0x7-when-temp-directory-is-full-on-linux-815584538.html

https://bugs.freedesktop.org/show_bug.cgi?id=100432

https://buddy.works/docs/on-premises/solving-problems/shared-memory

Socket 101

A connection between two computers uses a socket.

https://www.silabs.com/products/development-tools/software/micrium-os/micrium-tcp-ip-networking

http://personales.upv.es/rmartin/TcpIp/cap02s12.html

https://docs.oracle.com/javase/tutorial/networking/sockets/definition.html

https://cwiki.apache.org/confluence/display/HADOOP2/SocketTimeout

https://apur1e.wordpress.com/2018/03/23/299-tcp-ip-http-get-post/

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

15 October 2020

Gradle cheat sheet

Despite my preference for Maven, here it is a quick list of gradle (6.x) commands:

In gradle 7 has removed several tasks, and replaced by implementation, runtimeOnly, testImplementation, and testRuntimeOnly.

├── gradle
│ └── wrapper
│ ├── gradle-wrapper.jar
│ └── gradle-wrapper.properties
├── gradlew
├── gradlew.bat
├── settings.gradle
└── lib
├── build.gradle
└── src
├── main
│ └── java
│ └── demo
│ └── Library.java
└── test
└── java
└── demo
└── LibraryTest.java

1. basic build

gradle clean build

gradle assemble

gradle test

gradle init

2. eclipse java14 plugin

It has issues with wrapped gradle for older gradle (6.2--) gradle-wrapper.properties

Caused by: java.lang.NoClassDefFoundError: Could not initialize class org.codehaus.groovy.vmplugin.v7.Java7

plugins {
id 'eclipse'
}

gradle cleanEclipse eclipse

3. tasks (list of possible task to execute)

./gradlew tasks

4. springboot

gradle bootRun

5. version

./gradlew -version

6. sonarqube

plugins {
id "org.sonarqube" version "3.0"
}

sonarqube {
properties {
property "sonar.sourceEncoding", "UTF-8"
}
}

gradle sonarqube

7. debug/stacktrace

--stacktrace
--debug
--warning-mode=(all,fail,none,summary)

8. publish local maven

gradle publishToMavenLocal

available with:

apply plugin: 'maven-publish'

Another approach:

apply plugin: "maven"
group = "mygroupid"
version = "1.0.0"

repositories {
mavenLocal()
}

$ gradle clean build install

9. skip test

gradle build -x test

10. jar building

gradle jar

jar {
manifest {
attributes "Main-Class": "com.baeldung.fatjar.Application"
}
from {
configurations.compile.collect { it.isDirectory() ? it : zipTree(it) }
}
}

11. lombok

dependencies {
   compileOnly 'org.projectlombok:lombok:1.18.20'
   annotationProcessor 'org.projectlombok:lombok:1.18.20'

   testCompileOnly 'org.projectlombok:lombok:1.18.20'
   testAnnotationProcessor 'org.projectlombok:lombok:1.18.20'
}

12. dependencies

gradle dependencies

01 October 2020

OAuth 2.0 - OpenID Connect (OIDC)

OpenID Connect (OIDC) is an authentication layer on top of OAuth 2.0, an authorization framework.^[1] The standard is controlled by the OpenID Foundation.

Authorization Code Flow
Implicit Flow
Resource Owner Password Credentials Flow
Client Credentials Flow
Refresh Token Flow

direct grant

A way for a client to obtain an access token on behalf of a user via a REST invocation.

curl --location --request POST 'http://localhost:8180/auth/realms/spring2/protocol/openid-connect/token' \
--header 'Content-Type: application/x-www-form-urlencoded' \
--data-urlencode 'grant_type=password' \
--data-urlencode 'username=user2' \
--data-urlencode 'password=welcome1' \
--data-urlencode 'client_id=login-app2' \
--data-urlencode 'scope=openid'
 
curl --location --request POST 'http://localhost:8180/auth/realms/SpringBootKeycloak/protocol/openid-connect/token' \
--header 'Content-Type: application/x-www-form-urlencoded' \
--data-urlencode 'grant_type=password' \
--data-urlencode 'username=user1' \
--data-urlencode 'password=welcome1' \
--data-urlencode 'client_id=login-app' \
--data-urlencode 'client_secret=17c7b0a7-665d-4231-bc1f-818bda511d1f' \
--data-urlencode 'scope=openid'
 

{

"issuer": "http://localhost:8180/auth/realms/spring2",
"authorization_endpoint": "http://localhost:8180/auth/realms/spring2/protocol/openid-connect/auth",
"token_endpoint": "http://localhost:8180/auth/realms/spring2/protocol/openid-connect/token",
"introspection_endpoint": "http://localhost:8180/auth/realms/spring2/protocol/openid-connect/token/introspect",
"userinfo_endpoint": "http://localhost:8180/auth/realms/spring2/protocol/openid-connect/userinfo",
"end_session_endpoint": "http://localhost:8180/auth/realms/spring2/protocol/openid-connect/logout",
"jwks_uri": "http://localhost:8180/auth/realms/spring2/protocol/openid-connect/certs",
"check_session_iframe": "http://localhost:8180/auth/realms/spring2/protocol/openid-connect/login-status-iframe.html",
"grant_types_supported": [
- "authorization_code",
- "implicit",
- "refresh_token",
- "password",
- "client_credentials"
],
"response_types_supported": [
- "code",
- "none",
- "id_token",
- "token",
- "id_token token",
- "code id_token",
- "code token",
- "code id_token token" .....

Refresh token:

curl -X POST \
http://localhost:8180/auth/realms/spring2/protocol/openid-connect/token \
-H 'Content-Type: application/x-www-form-urlencoded' \
-d 'grant_type=refresh_token&client_id=login-app2&client_secret=welcome1&refresh_token=eyJhbGciOiJIUzI1NiIsInR5cCIgOiAiSldUIiwia2lkIiA6ICJhZTY0YTA1Mi1iMGJlLTRjY2UtODUxNS1lYTM0MDY5YWQ1YTMifQ.eyJleHAiOjE2MTE5NTI3MjYsImlhdCI6MTYxMTk1MDkyNiwianRpIjoiZjA4MjFhMGMtZjdmNi00YmRkLTg4YTctZmZkOTIwZTA0YWQ5IiwiaXNzIjoiaHR0cDovL2xvY2FsaG9zdDo4MTgwL2F1dGgvcmVhbG1zL3NwcmluZzIiLCJhdWQiOiJodHRwOi8vbG9jYWxob3N0OjgxODAvYXV0aC9yZWFsbXMvc3ByaW5nMiIsInN1YiI6ImRkNGU2ZTQ2LWIwMjQtNDZmYS05ZjUzLWM3OWE2MDM5YWIzZiIsInR5cCI6IlJlZnJlc2giLCJhenAiOiJsb2dpbi1hcHAyIiwic2Vzc2lvbl9zdGF0ZSI6IjUyYmU0ZTllLTVhNWMtNDFiZC1hZWVlLTg4ZjFiNTNhYjgwNiIsInNjb3BlIjoib3BlbmlkIGVtYWlsIHByb2ZpbGUifQ.FIAstcSWnq1ZUdHfgbIY9Z3u9_a2ywoFe9vxV-vwp6E'

Resources:

22 September 2020

ATAM - Architecture tradeoff analysis method

Consequences of architectural decisions in light of quality attributes requirements

ATAM is developed among technical professional, is not mandatory to include domain experts.

Steps: