Technology blogs for Developers by Developer.

JAVA_OPTS may use by Other applications, but only Tomcat will use CATALINA_OPTS. So if you're setting environment variables for use only by Tomcat, you'll be best advised to use CATALINA_OPTS, whereas if you're setting environment variables to be used by other java applications as well, you should put your settings in JAVA_OPTS. What can go in there! You can increase heap memory available to the JVM. You can open remote monitoring ports so that Jconsole on another system can watch how your Tomcat is running. You can add in a -server to switch from the client (quicker start, slower running) JVM to the server (slower starting, quicker running) JVM. You can increase java thread stack size using the -Xss option (same way to specify amount of memory as in -Xms and -Xmx as described in the "increase heap memory" link above. for more visit : http://www.sanjeevrathaur.com/2015/10/javaopts-variable-details.html

Memory Available to the Java JVM Increasing the memory available to the Java JVM JAVA_OPTS="-Xmx1024m -Xms256m" export JAVA_OPT Options description: -Xmx sets the maximum amount of memory that can be allocated to the JVM heap; here it is being set to 1024 megabytes. -Xms sets the initial amount of memory allocated to the JVM heap; here it is being set to 256 megabytes. Run Java JVM in Server Mode The Java JVM can optimize a number of things for server environments. You can explicitly select the Java HotSpot Server VM with the -server option. JAVA_OPTS="-Xmx1024m -Xms256m -server" export JAVA_OPT What the option means: -server instructs the launcher to use the Java HotSpot Server VM. PermGen Memory If you start getting java.lang.OutOfMemoryError: PermGen space error messages. You may want to include a "-XX:MaxPermSize" option in your JAVA_OPTS. JAVA_OPTS="-Xmx1024m -Xms256m -server -XX:MaxPermSize=128m" export...

Representational State Transfer (REST) has gained widespread acceptance across the Web as a simpler alternative to SOAP- and Web Services Description Language (WSDL)-based Web services. Key evidence of this shift in interface design is the adoption of REST by mainstream Web 2.0 service providers—including Yahoo, Google, and Facebook—who have deprecated or passed on SOAP and WSDL-based interfaces in favour of an easier-to-use, resource-oriented model to expose their services. Basics Fundamental REST didn't attract this much attention when it was first introduced in 2000 by Roy Fielding at the University of California, Irvine, in his academic dissertation, "Architectural Styles and the Design of Network-based Software Architectures," which analyzes a set of software architecture principles that use the Web as a platform for distributed computing. When it's attracting this much attention, a concrete implementation of a REST Web service follows four basic design p...

We increasingly live in a world where data doesn’t fit nicely into the tidy rows and columns of an RDBMS. Mobile, social, and cloud computing have spawned a massive flood of data. 80 percent of all enterprise data as unstructured. What's more, unstructured data is growing at twice the rate of structured data. As the world changes, data management requirements go beyond the effective scope of traditional relational databases. The first organizations to observe the need for alternative solutions were Web pioneers, government agencies, and companies that specialize in information services. Increasingly now, companies of all stripes are looking to capitalize on the advantage of alternatives like NoSQL and Hadoop: NoSQL to build operational applications that drive their business through systems of engagement, and Hadoop to build applications that analyze their data retrospectively and help deliver powerful insights. Enjoy !!!!!!

How To Choose A NoSQL Database? NoSQL databases are now part of web-scale architecture. The question is when to use what? Below, I try to compare the NoSQL data stores that I have worked with. Hopefully, it would be useful for programmers exploring and deciding the technology for their web-scale application. When to use NoSQL Before deciding on to use NoSQL instead of a SQL technology, you should ask yourself following questions about your use case (includes  ACID  test of your application) : Transactions vs No transactions (Do you need atomicity?) [Most NoSQL databases don’t support transactions] Consistent or eventual consistent (Are you okay with eventual consistency?) [Most support configurable consistency mode. You should test your scale with the consistency mode your application requires. For example, your performance test holds no good when done on “eventual consistency” mode and you decide to use hard consistency for your application.] Vertical...

You need to install logratate  Sudo apt-get update Sudo apt-get install logrotate For confirm logrotate successfully installed or not run : logrotate Default logrotate configuration are present in : /etc/logrotate.conf Example :  /var/log/tomcat7/catalina.out {      copytruncate       weekly       rotate 52       compress       missingok       create 640 tomcat7 adm       size 5M } What does it means : Copytruncate : Truncate  the  original  log  file  to  zero size in place after creating a  copy,  instead  of  moving  the  old  log  file  and  optionally creating a new one.  It can be used when some program cannot be told to close its  logfile  and  thus  might  c...

You can host multiple SSL certificates on one IP Address using Server Name Identification (SNI). SNI ? Although hosting several sites on a single virtual private server is not a challenge with the use of virtual hosts, providing separate SSL certificates for each site traditionally required separate IP addresses. The process has recently been simplified through the use of Server Name Indication (SNI), which sends a site visitor the certificate that matches the requested server name. SNI can only be used for serving multiple SSL sites from your web server and is not likely to work at all on other daemons, such as mail servers, etc. There are also a small percentage of older web browsers that may still give certificate errors. Wikipedia has an updated list of software that does and does not support this TLS extension. Setting Up SNI does need to have registered domain names in order to serve the certificates. The steps in this tutorial require the user to have root privileges. You can ...