Sofisma

 

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

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

 

Java SIGBUS

 Core dump of a lack of space at /tmp

:S

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
 

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

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.

1. Authorization Code Flow
2. Implicit Flow
3. Resource Owner Password Credentials Flow
4. Client Credentials Flow
5. 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:

• https://en.wikipedia.org/wiki/OpenID_Connect
  
• https://medium.com/@darutk/diagrams-and-movies-of-all-the-oauth-2-0-flows-194f3c3ade85
• https://www.ubisecure.com/single-sign-on/single-page-application-and-openid-connect/
  
• https://www.manning.com/books/spring-security-in-action
  
• https://www.baeldung.com/spring-boot-keycloak
• https://api-university.com/openid-connect-cheat-sheet/
• https://backstage.forgerock.com/docs/am/6/oidc1-guide/
• https://medium.com/@robert.broeckelmann/openid-connect-authorization-code-flow-with-red-hat-sso-d141dde4ed3f
• https://auth0.com/docs/flows/authorization-code-flow
  
• https://medium.com/@robert.broeckelmann/refresh-token-support-in-oauth2-oidc-debugger-c792b3a3f65a
• https://github.com/rcbj/oauth2-oidc-debugger
• https://github.com/nbarbettini/oidc-debugger
  Live here: https://oauthdebugger.com or https://oidcdebugger.com
• https://medium.com/devops-dudes/securing-spring-boot-rest-apis-with-keycloak-1d760b2004e
• https://www.keycloak.org/docs/4.8/server_admin/  
• https://auth0.com/docs/authorization/which-oauth-2-0-flow-should-i-use
• https://oauth.net/2/grant-types/implicit/
• https://www.javacodegeeks.com/2019/01/right-flow-job-oauth-2-0-flow-should-use.html  
• https://auth0.com/docs/flows/call-your-api-using-resource-owner-password-flow
• https://curity.io/resources/tutorials/howtos/flows/refresh-tokens/
• https://www.authlete.com/developers/pkce/#4-pcke-token-request
• https://auth0.com/docs/flows/call-your-api-using-the-authorization-code-flow
  

 

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:

1. Present the ATAM.
2. Present business drivers.
3. Present architecture.
4. Identify architectural approaches.
5. Generate quality attribute utility tree.
6. Analyze architectural approaches.
7. Brainstorm and prioritize scenarios.
8. Analyze architectural approaches.
9. Present results.
   

Quality Attributes:

• performance
• availability
• security
• modifiability
• interoperability
• integrability
• (observability)
  

 

Outputs of ATAM
 

•  A concise presentation of the architecture.
•  Articulation of business goals.
•  The quality requirement in terms of a collection of scenarios.
•  Mapping of architectural decisions to quality requirements.
•  A set of identified sensitivity and tradeoff points.
•  A set of risks and non-risks.
•  A set of risk themes.

https://concisesoftware.com/architecture-tradeoff-analysis-method-atam/

https://resources.sei.cmu.edu/library/asset-view.cfm?assetid=5177

http://devwebcl.blogspot.com/2017/05/software-architecture-books.html

https://resources.sei.cmu.edu/asset_files/TechnicalReport/2000_005_001_13706.pdf

 

Dynamic Proxies in Java Mini-Book

Technical proofed/reviewed:

* Dynamic proxies are such a tool. We can save thousands of lines of repetitive code with a single class. By taking a thorough look at how they work, we will recognize good use cases for them in our systems.

        https://www.infoq.com/minibooks/java-dynamic-proxies/

 

 

ADR (Architectural Decision Records)

The content of the ADR can have the following sections:

1. Title - Title of the decision record.
2. Decision - The decision that was made. For instance, use Elasticsearch for an enterprise-wide search API.
3. Status - Status can be proposed, accepted or superseded. If you make any decisions and you need to change them later, you can simply add a new record with the changed status.
4. Context - What is the context of this decision? It is important to capture the full context of the decision so that the reader knows the reasons behind it.
5. Consequences - In this section, you can add what would happen if this decision is made. It is important to list all consequences, both positive and negative.

https://github.com/joelparkerhenderson/architecture_decision_record 

https://github.com/npryce/adr-tools

 UPDATE: 2 years later we see the same in AWS: https://www.infoq.com/news/2022/06/aws-adr-guide/

The Twelve-Factor App

 From wikipedia:

The Twelve-Factor App methodology is a methodology for building software-as-a-service applications. These best practices are designed to enable applications to be built with portability and resilience when deployed to the web.

https://12factor.net/

I. Codebase
One codebase tracked in revision control, many deploys

II. Dependencies
Explicitly declare and isolate dependencies

III. Config
Store config in the environment

IV. Backing services
Treat backing services as attached resources

V. Build, release, run
Strictly separate build and run stages

VI. Processes
Execute the app as one or more stateless processes

VII. Port binding
Export services via port binding

VIII. Concurrency
Scale out via the process model

IX. Disposability
Maximize robustness with fast startup and graceful shutdown

X. Dev/prod parity
Keep development, staging, and production as similar as possible

XI. Logs
Treat logs as event streams

XII. Admin processes
Run admin/management tasks as one-off processes

 

Event Storming Rainbow

When trying to create a methodology/paradigm, but everybody starts changing colors.

Event Storming, a rainbow of post-it notes.

https://kalele.io/symbolsicons-for-event-storming/

https://github.com/wwerner/event-storming-cheatsheet

https://leanpub.com/introducing_eventstorming

https://eventnotes.io/pdf/cheatsheet-big-picture-exploration.pdf

https://developer.ibm.com/technologies/java/tutorials/reactive-in-practice-1/