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


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


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:


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)
9:30am 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)
10:15am 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) 


8:50am Thursday opening welcome Scott Hanselman (Microsoft), Rachel Roumeliotis (O'Reilly Media), Kelsey Hightower (Google)
9:20am Sustainability in open source Danese Cooper (PayPal)
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



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 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

25 May 2016


Working on a POC for ehcache Replicated 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:


20 May 2016

Knuth's Algorithm Java Impl

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


For now, only algorithms from

Also, it has code from Sedgewick.

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