Monday, 1 September 2014

Some concepts of Solr

This article has been moved to a different location.
Click here to read the entire article

Monday, 9 June 2014

Enabling JMX in Tomcat

Any Java program can be monitored using Jconsole. Jconsole is an user interface which comes by default with any JDK package, you just need to type jconsole on your terminal and it will show you the interface. Jconsole works along with JMX, which has to be enabled in the respective java program or JVM.

How to enable JMX in tomcat?

You to enable these variables while starting of the JVM. In tomcat you can simple enable them by using CATALINA_OPTS variable in file in bin folder of tomcat.{port to access}
-Djava.rmi.server.hostname={optional, allow what ip to access this Tomcat}
export CATALINA_OPTS="$CATALINA_OPTS -Djava.rmi.server.hostname="

To know more details about variables, you can check here,

After changing this, start the tomcat and then run jconsole from anywhere and connect using
"IP:port", if authentication is enable, enter the credentials also. Now you can see all the JVM stuff, threads, memory usages, CPU usages, GCs performed etc.

Friday, 25 April 2014

RSA server certificate CommonName (CN) '' does NOT match server name


I was getting this error on restarting of my Apache,

"I receive the Error: "RSA server certificate CommonName (CN) '' does NOT match server name"?"

And there was on website which was able to tell me that is something wrong, which is

In my case, I had missed an entry of "ServerName" directive in Apache virtual host configuration.

<VirtualHost _default_:443>

SSLEngine on
SSLCertificateFile /root/ssl/domain.crt
SSLCertificateKeyFile /root/ssl/server.key
SSLCertificateChainFile /root/ssl/bundle.crt


So after entering the ServerName, apache error.log file stopped showing the error message. And the website sslshopper also, started getting the certificate of diagnosis, which made me believe, that issue is resolved.

In general, you should also check
1. DNS entry (host name and IP is correct)
2. /etc/hosts file
3. while creating CSR file, did you miss the common name by any chance, In this case create a new CSR and Re-key the certificate and deploy new certificates.
4. Check in Apache or Nginx, ServerName must match, certificates are issued for a fix domain.

Tuesday, 25 February 2014

fb:share_button/fb:login_button/fb: failed to resize in 45s

I saw one strange issue while using fb_share button which I would like to share and How did I fix it.

When you use fb_share buttons with their stats, means you are using some javascript to get the starts and show beside of the button. When the page load it was working fine, but when you navigate to any other page by clicking on a link or button, and you do browser back to the same page again, it tries to load fb_share button again.. but it keep the textarea locked for 45 seconds, which was quite strange.

I guess it had to be with while fb tries to get the data it also tries to make the proper UI of the button, size and all, and during that period, it locks the textarea.

I started searching for the issue and got a pathetic solution on stackoverflow which says to use this css

.fb-share-button span,
.fb-share-button iframe {
    width: 120px! important;
    height: 25px! important;

And amazing part is, it works :)