27 December 2016

Big-O Comparison

Usually it's easier to see in a graph the complexity of functions:

Source: https://discuss.leetcode.com/topic/23858/strange-o-nlogn-c-solution-with-qsort-takes-only-4ms/2

http://cooervo.github.io/Algorithms-DataStructures-BigONotation/big-O-notation.html

29 November 2016

Good example of cube demonstrating the 3 factors necessary for scalability in microservices (it could be projected to different domains as well). Therefore if you scale in any axis will have an impact in another

http://theartofscalability.com/

http://microservices.io/articles/scalecube.html

https://www.benefitfocus.com/blogs/design-engineering/architecture-cubed

http://www.ossmentor.com/2015/01/scaling-microservices.html

https://github.com/arun-gupta/microservices/blob/master/slides/refactor-microservices.pdf

Dietzler’s law

Interesting law from Neal Ford quoting his colleague Terry Dietzler:

Dietzler’s Law for Access

Every Access project will eventually fail because, while 80% of what the user wants is fast and easy to create, and the next 10% is possible with difficulty, ultimately the last 10% is impossible because you can’t get far enough underneath the built-in abstractions, and users always want 100% of what they want.

Source: http://nealford.com/memeagora/2013/01/22/why_everyone_eventually_hates_maven.html

21 November 2016

Contributions

https://github.com/devwebcl/
http://stackoverflow.com/users/1413222/devwebcl
https://coderanch.com/u/218082/German-Gonzalez-Morris
https://projecteuler.net/profile/devwebcl.png
https://www.hackerrank.com/devwebcl

07 November 2016

Maven subprojects

A raw workaround, and work directly on a parent pom.xml into an eclipse workspace:

create workspace
create parent project
copy files/directories, overwriting (subdirectories)
import thru "Existing Maven Projects", and select parent project

however, it doesn't work as expected... I think the copy to directories is wrong, and only it should be a reference to the origin.

A much better explanation: http://websystique.com/maven/creating-maven-multi-module-project-with-eclipse/

UPDATE1: In the end, there is a quick difference as workaround: just import directly the parent pom.xml

31 October 2016

Bueno Bonito Barato

En Gestión de Proyectos (informaticos en particular), no existe el BBB (Bueno, Bonito, Barato) tal como en la vida real.

Por el dominio formal del tema, no se utiliza tanto estas siglas, pero sin dudas existen y es un tema tratado en este ambito.

Podemos ver en wikipedia (ver referencias originales) que se usan sinónimos, tal como:

Fast, Good, and Cheap,

Y de la misma forma, se solicita tomar solo 2 de ellas (Pick any two), en donde solo 2 de esas características pueden ser elegidas, ya que la tercera no sera cumplida por motivos de las anteriores :O

En fin, la idea es recordar este buen thumb-rule en el dia a dia de un proyecto...

Otros similares...

De Agilidad:

The Project Management Triangle:

28 October 2016

Architecture Certification

Cuatro de los "grupos" mas importantes que otorgan certificaciones de arquitectura:

20 October 2016

Swap Two Numbers

public class SwapTwoNumbers {

    public static void main(String[] args) {

        int x = 5, y = 10;

        x = x ^ y ^ (y = x);

        System.out.println("x = " + x);
        System.out.println("y = " + y);

    }

}

18 October 2016

Holgura

Una palabra clave de gestión de proyectos es holgura.

Esta traducción no siempre es fácil de encontrarla, total float o total slack.

16 October 2016

Pleonasmo

Despues de mucho tiempo pude encontrar la palabra que buscaba para la referencia de redundancias utilizadas de forma correcta, tiene valor expresivo y se utiliza como recurso estilístico

Uno de los ejemplos de forma correcta de su uso es el clásico libro de Vicente Perez Rosales: Recuerdos del Pasado.

06 September 2016

Oscon 2016, May Austin TX

This was the schedule for this conference, with the Keynotes I attended:

18.05.2016:

8:45am Wednesday opening welcome Kelsey Hightower (Google), Rachel Roumeliotis (O'Reilly Media), Scott Hanselman (Microsoft)

8:55am Keynote performance by Sammus Enongo Lumumba-Kasongo (Sammus)

9:05am Incremental revolution: What Docker learned from the open source fire hose Solomon Hykes (Docker)

9:20am Computer science artists unite! An open source retrospective to glimpse our future Angel Diaz (IBM)

9:30am How did I "git" here? A tale of a CS professor Kyla McMullen (University of Florida)

9:45am Huawei’s open source journey Sanqi Li (Huawei)

9:55am The case for a unified and interoperable open cloud ecosystem Sam Ramji (Cloud Foundry Foundation)

10:00am The unreasonable effectiveness of open data, open source, and open science Joseph Sirosh (Microsoft)

10:15am Closing remarks

11:05am Java 9 sneak peek: An embedded tale Matt Schuetze (Azul Systems)
11:55am Intro to Apache Spark for Java and Scala developers Ted Malaska (Cloudera)
1:50pm CarbonData : A new Hadoop-native file format for faster data analysis Jihong MA (Huawei)
2:40pm Open source and microservices: Your badass, next-gen application architecture Ken Owens (Cisco)
4:20pm Microservices war stories Blithe Rocher (Fastly)
5:10pm Civic data: Using open source data to create socially impactful data-driven products Vida Williams (Axis Partners, Inc)

19.05.2016:

8:50am Thursday opening welcome Scott Hanselman (Microsoft), Rachel Roumeliotis (O'Reilly Media), Kelsey Hightower (Google)

8:55am Open, closed, and demon haunted: An Internet of Things that act like inkjet printers Cory Doctorow (EFF)

9:05am Hiring awesome engineers: Looking beyond the Valley and the USA Erica Brescia (Bitnami)

9:20am Sustainability in open source Danese Cooper (PayPal)

9:30am Closing the loop: Open source community projects are changing healthcare Dana Lewis (W2OGroup)

9:45am Crossing the river by feeling the stones Simon Wardley (Leading Edge Forum (CSC))

10:00am O'Reilly Open Source Awards | Room: Ballroom D

10:10am Closing remarks
11:05am Static and dynamic data with Postgres, Kafka, and Bottled Water Chad Bailey (Heroku )
11:55am NoSQL's biggest lie: SQL never went away Matthew Revell (Exoscale)
1:50pm Real-time democratizing of event-driven big data Rachel Reese (Jet.com)
2:40pm Open source or proprietary: Choose wisely Patrick McFadin (DataStax)
4:20pm Java 8 puzzlers: The strange, the bizarre, and the wonderful Baruch Sadogursky (JFrog), Vikto
5:10pm A data-streaming architecture with Apache Flink Jamie Grier (data Artisans)

Open Source Convention - O'Reilly OSCON, May 16 - 19, 2016

http://conferences.oreilly.com/oscon/oscon-tx-2016/public/schedule/grid/public/2016-05-18

http://conferences.oreilly.com/oscon/oscon-tx-2016/public/schedule/grid/public/2016-05-19

09 August 2016

weblogic.security.SecurityInitializationException: Authentication for user weblogic denied

This is a common exception that is under authentication scope.
Googling you can find a lot of information related to boot.properties and ldap directory.

Nevertheless, this time is about the Managed Server cannot communicate with Admin Server, thus it starts in independent mode, but being the very first time it doesn't have users from realms, finally any user cannot authenticate to MS.

Well, solving the name MBP.local (in my case), everything is solved. (etc/hosts :P )

<Aug 8, 2016 9:13:58 AM EDT> <Emergency> <Management> <BEA-141151> <The admin server could not be reached at http://MBP.local:7001.>
<Aug 8, 2016 9:13:58 AM EDT> <Info> <Configuration Management> <BEA-150018> <This server is being started in managed server independence mode in the absence of the admin server.>

....
.....
....

<Aug 8, 2016 9:13:59 AM EDT> <Notice> <Security> <BEA-090082> <Security initializing using security realm myrealm.>
<Aug 8, 2016 9:13:59 AM EDT> <Critical> <Security> <BEA-090403> <Authentication for user weblogic denied>
<Aug 8, 2016 9:13:59 AM EDT> <Critical> <WebLogicServer> <BEA-000386> <Server subsystem failed. Reason: weblogic.security.SecurityInitializationException: Authentication for user weblogic denied
weblogic.security.SecurityInitializationException: Authentication for user weblogic denied
at weblogic.security.service.CommonSecurityServiceManagerDelegateImpl.doBootAuthorization(CommonSecurityServiceManagerDelegateImpl.java:966)
at weblogic.security.service.CommonSecurityServiceManagerDelegateImpl.initialize(CommonSecurityServiceManagerDelegateImpl.java:1054)
at weblogic.security.service.SecurityServiceManager.initialize(SecurityServiceManager.java:873)
at weblogic.security.SecurityService.start(SecurityService.java:141)
at weblogic.t3.srvr.SubsystemRequest.run(SubsystemRequest.java:64)
Truncated. see log file for complete stacktrace
Caused By: javax.security.auth.login.FailedLoginException: [Security:090303]Authentication Failed: User weblogic weblogic.security.providers.authentication.LDAPAtnDelegateException: [Security:090295]caught unexpected exception
at weblogic.security.providers.authentication.LDAPAtnLoginModuleImpl.login(LDAPAtnLoginModuleImpl.java:251)
at com.bea.common.security.internal.service.LoginModuleWrapper$1.run(LoginModuleWrapper.java:110)
at java.security.AccessController.doPrivileged(Native Method)
at com.bea.common.security.internal.service.LoginModuleWrapper.login(LoginModuleWrapper.java:106)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
Truncated. see log file for complete stacktrace
>
<Aug 8, 2016 9:13:59 AM EDT> <Notice> <WebLogicServer> <BEA-000365> <Server state changed to FAILED>
<Aug 8, 2016 9:13:59 AM EDT> <Error> <WebLogicServer> <BEA-000383> <A critical service failed. The server will shut itself down>

Tabs & Spaces

A concurrent issue in a Java project with different developers using different IDE's. Now we have three: Eclipse, Netbeans, and IntelliJ.

Workaround for Eclipse:
(replace tabs by spaces, not very elegant, but it works)

29 July 2016

Project Euler @Hackerrank

I've been playing around with HackerRank, which has hard problems, contests and tutorials to become a better developer.

One (of many) interesting features is to have ProjectEuler+ open contest, which is the same PE with timeout handicap, thus becoming much harder, seeking for more elegant solutions :P

30 June 2016

Regular Expressions Puzzles

On 2013 the famous MIT hunt gave a Regexp puzzle, which became very popular.
It appeared several similar puzzles, but there are a couple sites with similar contraption :

Give it a try !

MIT puzzle:

More interesting sites:

https://regex101.com/r/wO2zI4/1

https://regexcrossword.com/challenges/intermediate/puzzles/1

https://engineering.linkedin.com/puzzle

https://www.cheatography.com/davechild/cheat-sheets/regular-expressions/

http://mariolurig.com/crossword/

25 May 2016

net.sf.ehcache.CacheException

Working on a POC for ehcache Replicated demo:
https://github.com/devwebcl/java-caches-demo

I hit an issue for Tomcat in Mac OS X using ehcache listener for replication:

May 25, 2016 11:07:41 AM org.apache.catalina.core.StandardContext listenerStart
SEVERE: Exception sending context initialized event to listener instance of class de.consol.research.cache.part03.ehcache.ServletContextListener
net.sf.ehcache.CacheException: Can't assign requested address

This is solved by setting Java system property:

-Djava.net.preferIPv4Stack=true

20 May 2016

Knuth's Algorithm Java Impl

I have created a repository for Java implementations of Knuth algorithm found at TAOCP.

https://github.com/devwebcl/Knuth

For now, only algorithms from 7.2.1.2

Also, it has code from Sedgewick.

02 May 2016

WebLogic access log files

Many times in development side, we want to access log files for a remote weblogic.
One easy way (to avoid several constraints) is to have like-a webpage to see these files.

This can be achieved easily with weblogic.xml parameters:

Different WebLogic Server Tools
Bunch of tools to help WLS admin, debugging, etc.

This first version is a war file to access log files from remote client through an HTML file generated by WLS.
the core idea is to show the directories/files of a particular server, this way we can debug easily.

https://github.com/devwebcl/wls_contraption

The weblogic.xml is:

<?xml version="1.0" encoding="UTF-8"?>
<wls:weblogic-web-app xmlns:wls="http://xmlns.oracle.com/weblogic/weblogic-web-app" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd http://xmlns.oracle.com/weblogic/weblogic-web-app http://xmlns.oracle.com/weblogic/weblogic-web-app/1.3/weblogic-web-app.xsd">
    <wls:weblogic-version>10.3.6</wls:weblogic-version>
    <wls:context-root>logs_retrieval</wls:context-root>


    <wls:container-descriptor>
        <wls:index-directory-enabled>true</wls:index-directory-enabled>
    </wls:container-descriptor>

    <wls:virtual-directory-mapping>
        <wls:local-path>/u01/domains1036/MYDOMAIN</wls:local-path>
        <wls:url-pattern>/servers/logs/*</wls:url-pattern>
    </wls:virtual-directory-mapping>

    <wls:virtual-directory-mapping>
        <wls:local-path>/u01/domains1036/MYDOMAIN/</wls:local-path>
        <wls:url-pattern>/logs/*</wls:url-pattern>
    </wls:virtual-directory-mapping>

    
    <wls:virtual-directory-mapping>
        
        <wls:local-path>/</wls:local-path>
        <wls:url-pattern>/tmp/*</wls:url-pattern>
    </wls:virtual-directory-mapping>


    <wls:jsp-descriptor>
    <wls:page-check-seconds>0</wls:page-check-seconds>
    </wls:jsp-descriptor>
    <wls:container-descriptor>
    <wls:servlet-reload-check-secs>0</wls:servlet-reload-check-secs>
    <wls:resource-reload-check-secs>0</wls:resource-reload-check-secs>
    </wls:container-descriptor>

</wls:weblogic-web-app>

07 April 2016

Fowler's ideas

Interesting posts from Martin Fowler, most are his ideas, however there some that is referring to third idea... as usual, it is referenced correctly in his document:

- CQRS
- Event Sourcing
- Parallel Model
- ReportingDatabase
- BlueGreen Deployment
- Canary Release

...

22 March 2016

Portadas libros Educacion Aymara-Castellano

Continuando con la preservación de libros de proyecto OEA:

16 March 2016

Catastrophic Backtracking

RegExp Playground

This repository contains several regexp examples.

Examples

1. Catastrophic Backtracking

This is Java example of backtracking catastrophic shown in Coding Horror post This is a known behavior when using nesting repetition operators, that has been analyzed in stackoverlow, regular expressions dedicated sites.
It can be seen the exponential explosion that take to parse using regexp for a simple pattern:

(x+x+)y+

Details of this issue can be found on the above links.

Execute

mvn clean package
mvn exec:java -Dexec.mainClass="cl.devweb.regexp.exploit.CatastrophicBacktracking"

Rule of Thumb - Solution

The solution is simple. When nesting repetition operators, make absolutely sure that there is only one way to match the same match. If repeating the inner loop 4 times and the outer loop 7 times results in the same overall match as repeating the inner loop 6 times and the outer loop 2 times, you can be sure that the regex engine will try all those combinations.

OUTPUT

 mvn exec:java -Dexec.mainClass="cl.devweb.regexp.exploit.CatastrophicBacktracking"
[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building regexp-exploit 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- exec-maven-plugin:1.4.0:java (default-cli) @ regexp-exploit ---
Found value: xxxxxxxxxxxxxy  timer=113.2 μs
Invalid match of 1 chars took 20.97 μs
Invalid match of 2 chars took 14.28 μs
Invalid match of 3 chars took 21.82 μs
Invalid match of 4 chars took 149.2 μs
Invalid match of 5 chars took 26.92 μs
Invalid match of 6 chars took 43.73 μs
Invalid match of 7 chars took 80.80 μs
Invalid match of 8 chars took 135.6 μs
Invalid match of 9 chars took 207.1 μs
Invalid match of 10 chars took 240.6 μs
Invalid match of 11 chars took 442.9 μs
Invalid match of 12 chars took 848.0 μs
Invalid match of 13 chars took 1.623 ms
Invalid match of 14 chars took 2.504 ms
Invalid match of 15 chars took 4.339 ms
Invalid match of 16 chars took 8.163 ms
Invalid match of 17 chars took 16.60 ms
Invalid match of 18 chars took 33.27 ms
Invalid match of 19 chars took 69.98 ms
Invalid match of 20 chars took 138.2 ms
Invalid match of 21 chars took 268.9 ms
Invalid match of 22 chars took 537.9 ms
Invalid match of 23 chars took 977.8 ms
Invalid match of 24 chars took 2.132 s
Invalid match of 25 chars took 4.260 s
Invalid match of 26 chars took 8.433 s
Invalid match of 27 chars took 17.18 s
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 34.977 s
[INFO] Finished at: 2016-03-16T12:38:59-03:00
[INFO] Final Memory: 9M/245M
[INFO] ------------------------------------------------------------------------

We can see taking a Thread Dump, where is spending (wasting?) most of the time:

"main" #1 prio=5 os_prio=31 tid=0x00007f8f9a006000 nid=0x1303 runnable [0x000000010a718000]
   java.lang.Thread.State: RUNNABLE
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4785)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4785)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4785)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4785)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4785)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4785)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4785)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
    at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658)
    at java.util.regex.Pattern$Loop.matchInit(Pattern.java:4801)
    at java.util.regex.Pattern$Prolog.match(Pattern.java:4741)
    at java.util.regex.Pattern$Start.match(Pattern.java:3461)
    at java.util.regex.Matcher.search(Matcher.java:1248)
    at java.util.regex.Matcher.find(Matcher.java:637)
    at cl.devweb.regexp.exploit.CatastrophicBacktracking.main(CatastrophicBacktracking.java:81)

TODO

add more examples :)

License

MIT . .

15 March 2016

Maven Cheat Sheet

Some reminder for Maven:

mvn clean package -DskipTests -Dmaven.javadoc.skip=true -Dhttps.protocols=TLSv1.2

1. Use a different settings.xml

mvn --settings ~/.m2/YourOwnSettings.xml clean install

mvn -s ~/.m2/YourOwnSettings.xml clean install

2. Jboss tasks:

mvn jboss-as:deploy
mvn jboss-as:redeploy
mvn jboss-as:undeploy

3. Eclipse Maven clean:
(retired)

mvn eclipse:eclipse
mvn eclipse:clean
mvn install

4. set java version:

<project>
[...]
<build>
[...]
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.4</source>
<target>1.4</target>
</configuration>
</plugin>
</plugins>
[...]
</build>
[...]
</project>

5. Missing Maven dependencies in Eclipse Project

   workaround to have an eclipse maven project

6. basic maven structure

src/main/java

- src
    - main
          - java
          - resources
          - webapp
     - test
          - java
          - resources

- target

7. packaging:

<packaging>jar</packaging>

8. executing from maven:

add the following plugin to pom.xml:

<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.2.1</version>
<configuration>
<mainClass>com.myorganisationname.common.App</mainClass>
</configuration>
<arguments> -Dlog4j.configurationFile=/tmp/log4j2.xml </arguments> <classpathScope>test</classpathScope>
</plugin>

and run it with:

mvn exec:java

9. skipping test:

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.19.1</version>
<configuration>
<skipTests>true</skipTests>
</configuration>
</plugin>

or

      mvn install -DskipTests

or

     mvn install -Dmaven.test.skip=true

10. Multiple Module Projects

<packaging>pom</packaging>

<modules>
<module>guide-ide-eclipse-site</module>
<module>guide-ide-eclipse-core</module>
<module>guide-ide-eclipse-module1</module>
</modules>

Add the parent to the POMs of the new modules:

<parent>
<groupId>guide.ide.eclipse</groupId>
<artifactId>guide-ide-eclipse</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>

mvn install
mvn eclipse:eclipse

http://maven.apache.org/plugins/maven-eclipse-plugin/reactor.html

11. web archetype

mvn archetype:generate -DgroupId=cl.devweb -DartifactId=wls_log_retrieval -DarchetypeArtifactId=maven-archetype-webapp -DinteractiveMode=false

12. copy dependencies:

 mvn dependency:copy-dependencies -DoutputDirectory=OUTPUT_DIR

13. tomcat

mvn tomcat7:deploy
mvn tomcat7:undeploy
mvn tomcat7:redeploy

14. verbose class

mvn test -DjvmArgs="-verbose:class"

15. web.xml-less
(servlet 3.0+)


<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-war-plugin</artifactId>
 <version>2.6</version>
 <configuration>
  <failOnMissingWebXml>false</failOnMissingWebXml>
 </configuration>
</plugin>

16. weblogic

              mvn com.oracle.weblogic:weblogic-maven-plugin:deploy


           mvn com.oracle.weblogic:weblogic-maven-plugin:undeploy


            <plugin>
                <groupId>com.oracle.weblogic</groupId>
                <artifactId>weblogic-maven-plugin</artifactId>
                <version>12.1.3-0-0</version>
                <configuration>
                    <adminurl>t3://127.0.0.1:7001</adminurl>
                    <user>weblogic</user>
                    <password>welcome1</password>
                    <upload>true</upload>
                    <action>deploy</action>
                    <remote>true</remote>
                    <verbose>true</verbose>
                    <source>target/${project.artifactId}.${project.packaging}</source>
                    <name>${project.artifactId}</name>
                    <targets>AdminServer</targets>
                </configuration>
            </plugin>

17. debug flag

mvn -X

mvn -e

18. update (when it does not find jar)
Use the -U flag to force Maven to update dependencies:

mvn -U package

19. dependencies

mvn dependency:tree

     -Dverbose

20. skip javadoc

-Dmaven.javadoc.skip=true

21. assigning different https protocol version :
(to avoid: Received fatal alert: protocol_version)

-Dhttps.protocols=TLSv1.2

22. identifying excluding dependencies

mvn dependency:tree -Dverbose -Dincludes=log4j:log4j

i.e.:

[German@KDU foo-ejemplo (feature/ggonzalez/refactoring)]$ mvn dependency:tree -Dverbose -Dincludes=org.springframework:spring-core
[INFO] Scanning for projects...
[INFO]
[INFO] ---------------< cl.bar:foo-ejemplo >---------------
[INFO] Building foo-ejemplo 1.0.0
[INFO] --------------------------------[ war ]---------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:2.8:tree (default-cli) @ foo-ejemplo ---
[INFO] cl.bar:foo-ejemplo:war:1.0.0
[INFO] \- cl.bar.plataforma.common:foo-ejemplo-lib:jar:1.0.1:compile
[INFO]    +- org.springframework:spring-context:jar:4.2.1.RELEASE:compile
[INFO]    | +- org.springframework:spring-aop:jar:4.2.1.RELEASE:compile
[INFO]    | | \- (org.springframework:spring-core:jar:4.2.1.RELEASE:compile - omitted for duplicate)
[INFO]    | +- org.springframework:spring-beans:jar:4.2.1.RELEASE:compile
[INFO]    | | \- (org.springframework:spring-core:jar:4.2.1.RELEASE:compile - omitted for duplicate)
[INFO]    | +- org.springframework:spring-core:jar:4.2.1.RELEASE:compile
[INFO]    | \- org.springframework:spring-expression:jar:4.2.1.RELEASE:compile
[INFO]    |     \- (org.springframework:spring-core:jar:4.2.1.RELEASE:compile - omitted for duplicate)
[INFO]    \- org.springframework:spring-jdbc:jar:4.2.1.RELEASE:compile
[INFO]       +- (org.springframework:spring-core:jar:4.2.1.RELEASE:compile - omitted for duplicate)
[INFO]       \- org.springframework:spring-tx:jar:4.2.1.RELEASE:compile
[INFO]          \- (org.springframework:spring-core:jar:4.2.1.RELEASE:compile - omitted for duplicate)

23. Add local dependencies directly

<dependency>
<groupId>com.sample</groupId>
<artifactId>sample</artifactId>
<version>1.0</version>
<scope>system</scope>
<systemPath>${project.basedir}/src/main/resources/yourJar.jar</systemPath>
</dependency>

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-war-plugin</artifactId>
            <version>3.2.0</version>
            <configuration>
                <failOnMissingWebXml>true</failOnMissingWebXml>
                <webResources>
                    <resource>
                       <directory>${project.basedir}/lib</directory>
                       <targetPath>WEB-INF/lib</targetPath>
                    </resource>
                </webResources>
            </configuration>
        </plugin>

24. purge local
to clean up old dependencies (when someone changes a library but didn't upgrade the version, so we have a stale version)

mvn clean dependency:purge-local-repository

25. maven options for -XX

export MAVEN_OPTS="-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/tmp/"

<plugins>
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <configuration>
      <argLine>-Xms512m -Xmx512m -XX:PermSize=256m -XX:+HeapDumpOnOutOfMemoryError -XX:MaxPermSize=512m</argLine>
    </configuration>
</plugin>
</plugins>

<properties>
<argLine>-Xms512m -Xmx512m -XX:PermSize=256m -XX:+HeapDumpOnOutOfMemoryError -XX:MaxPermSize=512m</argLine>

26. sonar

mvn sonar:sonar -Dsonar.host.url=http://127.0.0.1:9000 -Dsonar.login=d676f79d8ba83cdcf69f38f8471f0284ee242e09

for remote server:
settings.xml:

<settings xmlns="http://maven.apache.org/POM/4.0.0"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
                      http://maven.apache.org/xsd/settings-1.0.0.xsd">

   <pluginGroups>
        <pluginGroup>org.sonarsource.scanner.maven</pluginGroup>
   </pluginGroups>
   <profiles>
        <profile>
            <id>sonar</id>
            <activation>
                <activeByDefault>true</activeByDefault>
            </activation>
            <properties>
                
                <sonar.host.url>
                    http://127.0.0.1:9000
                </sonar.host.url>
            </properties>
        </profile>
   </profiles>
</settings>

27. javadoc 8 issues

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-javadoc-plugin:2.9.1:jar (attach-javadocs) on project foo-api-rest: MavenReportException: Error while creating archive:
[ERROR] Exit code: 1 - /Users/German/development/workspace-oepe/foo-api-rest/src/main/java/cl/bar/plataformacomercial/foo/api/aop/HttpUtil.java:20: warning: no description for @param
[ERROR]      * @param request
[ERROR]        ^

This can be solved: https://devwebcl.blogspot.com/2016/01/jdk8-self-closing-element-not-allowed.html

28. maven deploy nexus/azure artifacts
before configuring: settings.xml, Plugins, distributionManagement, snapshotRepository

mvn clean deploy

https://www.baeldung.com/maven-deploy-nexus

29. install a library in the local repo

mvn install:install-file -DgroupId=cl.devweb.rbac -DartifactId=test -Dversion=1.0.0 -Dfile=test-rbac.jar -Dpackaging=jar -DgeneratePom=true

30. list system properties from Maven:

mvn help:system

    <build>
        <plugins>
            <plugin>
                <artifactId>maven-antrun-plugin</artifactId>
                <version>1.6</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>run</goal>
                        </goals>
                        <configuration>
                            <target>
                                <property environment="env" />
                                <echoproperties />
                            </target>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

31.
wsdl jar
to be tested jar wsdl client proxies :


                      <plugin>
                <groupId>org.jvnet.jax-ws-commons</groupId>
                <artifactId>jaxws-maven-plugin</artifactId>
                <version>2.3</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>wsimport</goal>
                        </goals>
                        <configuration>
                            <wsdlDirectory>${basedir}/src/main/resources/wsdl/</wsdlDirectory>
                            <wsdlLocation>wsdl/endpoint_sample_wsdl.wsdl</wsdlLocation>
                            <sourceDestDir>${basedir}/src/main/java</sourceDestDir>

32.
list of licenses

mvn license:add-third-party

33. .m2 corrupt
Many times when there is a problem downloading jar files from any maven repository, the quick solution is to delete local reference at .m2.

34.
integration test (failsafe)

mvn verify

35.
Operating System (OS) profiles:

   <profiles>
     <profile>
        <id>Windows</id>
        <activation>
          <os>
            <family>Windows</family>
          </os>
        </activation>
        <properties>
          <script.extension>.cmd</script.extension>
        </properties>
      </profile>
      <profile>
        <id>unix</id>
        <activation>
          <os>
            <family>unix</family>
          </os>
        </activation>
        <properties>
          
          <script.extension></script.extension>
        </properties>
      </profile>
    </profiles>

36.
creates classpath

mvn dependency:build-classpath

37.
add new repositories to settings.xml
many maven repos have modular repos for release, snapshots, thirdparties...

<repositories>
   <repository>
       <id>maven-releases</id>
       <url>http://localhost:8081/repository/maven-releases/</url>
       <layout>default</layout>
       <releases>
           <enabled>true</enabled>
       </releases>
       <snapshots>
           <enabled>false</enabled>
       </snapshots>
   </repository>
   <repository>
       <id>maven-snapshots</id>
       <url>http://localhost:8081/repository/maven-snapshots/</url>
       <layout>default</layout>
       <releases>
           <enabled>false</enabled>
       </releases>
       <snapshots>
           <enabled>true</enabled>
       </snapshots>
   </repository>
   <repository>
       <id>thirdparty</id>
       <url>http://nexus.cl:8081/repository/thirdparty/</url>
       <layout>default</layout>
       <releases>
           <enabled>true</enabled> 
       </releases>
       <snapshots>
           <enabled>false</enabled>
       </snapshots>
   </repository>
</repositories>

38. hello world antrun
(and writing to a file a timestamp).

mvn antrun:run@tmp-echo

<execution>
    <id>tmp-echo</id>
    <phase>generate-resources</phase>
    <goals>
        <goal>run</goal>
    </goals>
    <configuration>
        <target>
            <tstamp>
                 <format property="last.updated" pattern="yyyy-MM-dd hh:mm:ss"/>
            </tstamp>
            <echo>Hello world!</echo>
            <echo message="${last.updated}"/>
            <concat destfile="log.txt" append="yes" fixlastline="yes">${last.updated}</concat>
            <concat destfile="log.txt" append="yes" fixlastline="yes">
                <path path="hola.txt"/>
            </concat>
        </target>
    </configuration>
</execution>

39. Owasp Dependency-check-maven
open source vulnerable libraries.

mvn dependency-check:check

            <plugin>
                <groupId>org.owasp</groupId>
                <artifactId>dependency-check-maven</artifactId>
                <version>5.2.4</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>check</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

40. Modernizer Maven Plugin
yet another static analyzer

<plugin>
<groupId>org.gaul</groupId>
<artifactId>modernizer-maven-plugin</artifactId>
<version>2.0.0</version>
<configuration>
    <javaVersion>1.8</javaVersion>
</configuration>
</plugin>

41. springboot startup

mvn spring-boot:run

42. javadoc plugin

mvn javadoc:javadoc

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<version>2.9.1</version>
<executions>
<execution>
<id>attach-javadocs</id>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>

43. Overriding managed version maven dependency

parent pom spring boot 2.x
version 1.x can override a version easily by replacing properties of a library:

<properties>
<json.version>20180130</json.version>
</properties>

however now with 2.0 it must be avoided to use parent starter and add manually each dependency. From 1, 2 & 3

<dependencyManagement>
<dependencies>
<dependency>
...
...
...

44. logging stdout
Maven can log with:

-l log file
--log-file log.txt

or using tee would be better (we can redirect stdout to a file)

mvn-all2.bat | tee /a log3.txt

45. profile command line
to execute a profile (by using the maven repository) use -P argument:

mvn clean package -P perfil

    <profiles>
        <profile>
            <id>perfil</id>
            <repositories>
                <repository>
                    <snapshots>
                        <enabled>false</enabled>
                    </snapshots>
                    <id>company-releases</id>
                    <name>company-releases</name>
                    <url>https://host:port/repository/maven-releases</url>
                </repository>

46. internal repository in pom.xml

<project>
...

<repositories>
   <repository>
         <id>my-internal-site</id>
         <url>http://myserver/repo</url>
    </repository>
</repositories>
...
</project>

47. docker

mvn clean install dockerfile:build

       <plugin>
            <groupId>com.spotify</groupId>
            <artifactId>dockerfile-maven-plugin</artifactId>
            <version>1.4.0</version>
        </plugin>

48. jar without version

<build>
<finalName>${project.artifactId}</finalName>

49. jar executable

      <plugin>
       <groupId>org.apache.maven.plugins</groupId>
       <artifactId>maven-jar-plugin</artifactId>
   <version>3.2.0</version>
   <configuration>
       <archive>
         <manifest>
           <addClasspath>true</addClasspath>
           <classpathPrefix>lib/</classpathPrefix>
           <mainClass>cl.devweb.test.encrypt.Test1Json</mainClass>
         </manifest>
         </archive>
     </configuration>
     </plugin>

50. jar dependencies - fat jar

    <plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>cl.devweb.test.encrypt.Test1Json</mainClass>
          </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
    </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>3.3.0</version>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                </configuration>

                <executions>
                    <execution>
                        <id>make-assembly</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>

            </plugin>

51. copy resources

        <plugin>
            <artifactId>maven-resources-plugin</artifactId>
            <version>3.2.0</version>
            <executions>
                <execution>
                    <id>copy-resource-one</id>
                    <phase>package</phase>
                    <goals>
                        <goal>copy-resources</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>C:/Users/germagon/tmp/tmp</outputDirectory>
                        <resources>
                            <resource>
                                <directory>target</directory>
                                <includes>
                                    <include>oci-cli-oke-fd-${version}-jar-with-dependencies.jar</include>
                                </includes>
                            </resource>
                        </resources>
                    </configuration>
                </execution>
            </executions>
        </plugin>