Scala Basics - Functions

You can define function with "def"

scala> def pageVisitCount(session: Int): Int = session + 1 pageVisitCount: (session: Int)Int scala> var totalPageCount = pageVisitCount(1) totalPageCount: Int = 2 scala> def message() = "Hello Scala" message: ()java.lang.String scala> message() res0: java.lang.String = Hello Scala scala> message res1: java.lang.String = Hello Scala

Even you can able to call function without parenthesis if it doesn't have arguments.

Google Open Source Blog: The Go project reaches a major milestone: Go 1

Google Open Source Blog: The Go project reaches a major milestone: Go 1: In November 2009 Google announced the Go project , a new open source programming language. Since then more than 200 outside contributors ...

Scala Basics - Variables

You can define variable by "var" keyword

scala> var message="Hello Scala" message: java.lang.String = Hello Scala scala> var count=7 count: Int = 7

These two example we have created variables of type String and Int.Remember you can able to change message and count binding, since it's declared by "var".

Scala Basics - Simple Expression

Here is simple expression in Scala.

Scala> 7 + 7 res0: Int = 14 Scala> 4.5+9.3 res0: Double = 13.8

Scala interpreter automatically created value name(res0) for result of the expression. Last expression, res0 has Double type and stores 13.8 value.

You can define you're own name for a expression through "val".

scala> val result = 4*5 result: Int = 20

You cann't change the binding to a val.Almost everything in Scala is an expression.

Scala Basics - Interpreter for testing/learning!

Once you're machine installed with scala, then starting scala interpreter is easy

Note: refer this post for Scala install instructions for Ubuntu

$ scala

Welcome to Scala version 2.9.1.final (Java HotSpot(TM) Server VM, Java 1.6.0_26).
Type in expressions to have them evaluated.
Type :help for more information.

scala>

Now you're machine is ready for testing Scala code!

Scala - General Information

Scala is a concise, elegant, type-safe programming language that integrates object-oriented and functional features.It is fully interoperable with Java.

Scala and Java
Scala programs run on the Java Environment(JVM), so it compatible with Java. it makes Scala to use any existing Java Libraries/Applications.

Scala can able to calls/refers any Java code similarly Java can calls/refers any Scala code.

Scalar compiler performance is more reliable and well supports Java Byte Code.

Latest stable release & more information available here.

Scala 2.9.2 RC1

Scala 2.9.2 RC1 is available, it includes many bugfixes,but for testing purpose only.

More information available here.

JDK 8 - State of the Lambda

New edition of the State of the Lambda is available here.

RR's Random Ramblings: Java Tuning in a Nutshell - Part 1

Looks interesting....

RR's Random Ramblings: Java Tuning in a Nutshell - Part 1: While delivering a training recently, I got a request to put together a JVM tuning cheat sheet. Given the 50+ parameters available on the ...

Release - SPRING DATA MONGODB 1.0.1 GA!

Spring released it's first Spring Data MongoDB 1.0.1 GA, it's major release with major bug fixes(entity mapping, query execution and added a converter for UUIDs out of the box).

See Downloads,  JavaDoc and Reference Documentation for more information.

SPRING DATA JPA 1.1.0 RC1 AND 1.0.3 GA RELEASED

It includes lots of new features and bug fixes.Highlights are

* Support for locking
* Support for @IdClass in entities
* Support for LessThanEqual and GreaterThanEquals, True/False keywords in query methods
* Added CDI integration for repositories
* Improved parameter binding for derived queries for null values

More information

1.0.3.RELEASE - Maven artifacts | JavaDocs | Reference Documentation | Changelog

1.1.0.RC1 - Maven artifacts | JavaDocs | Reference Documentation | Changelog

GlassFish Server 3.1.2!

After seven months(since release 3.1.1), Oracle has been released GlassFish Server 3.1.2

Release notes and downloads are available here

Difference between Servlet container and Application server

Servlet Container - Tomcat 5/6/7, Jetty,etc

It supports a application which is based on Servlet Technology,  it also handles extension of the servlet technology such as JSP, JSTL,etc.

Possible to deploy most of the JavaEE Technologies on Servlet container, For that we have to add respective Technology APIs(either by maven repo/ant) on your application

Application Server: WebLogic, JBoss, GlassFish,etc

It supports a application which is based on JavaEE Technologies - EJB,Servlet,JSP,JF,JMS,JTA,etc.

Typesafe Stack - Release 2.0

Typesafe stack has been release version 2.0. Install instructions are available here for different operating system.

What's TypeSafe?

It's a stack for builing scalable software applications in Java and Scala. It includes

1. Scala

It's a general purpose programming language designed to express common programming patterns in a concise, elegant, and type-safe way. It smoothly integrates features of object-oriented and functional languages, enabling Java and other programmers to be more productive.

2. Akka

It's a event-driven middleware, with Scala and Java APIs.

3. Play

It's a Scala framework - easier to build web applications with Java & Scala.

Go through Documents and try different (giter8) template projects available.

Good Ruby on Rails Resources

These reference resources are very helpful and make you good in development and understand of  Ruby on Rails.

Official Rails Doc
General reference for Rails
Rails API docs with usage notes

Release - Rails 3.2.2

Rails 3.2.2 has been released. it contains two major security fixes and lots bug fixes.

Some of the major changes are

* Log files are always flushed

* Failing tests will exit with nonzero status code

* Elimination of calls to deprecated methods

* Query cache instrumentation includes bindings in the payload

* Hidden checkbox values are not set if the value is nil

* Various Ruby 2.0 compatibility fixes

More information about source and change log are available here

If you want to try latest rails on you're app, follow install and setup instructions which is available on official rubyonrails.org.

PHP 5.4.0 released!

The PHP development team announced PHP 5.4.0. It includes a large number of new features and bug fixes.


Some of the key new features include: traits, a shortened array syntax, a built-in webserver for testing purposes and more. PHP 5.4.0 significantly improves performance, memory footprint and fixes over 100 bugs.

More details available in release announcement.

Open source release - WindowTester Pro

Google announced the open sourcing release of WindowTester Pro. It is a UI test generation tool for testing SWT and Swing Java applications. WindowTester Pro eliminates the need to manually create test cases to test GUIs by automating the process of GUI testing. Using WindowTester Pro, developers can easily create tests for every GUI they create. Automating GUI testing increases the productivity of both the developer and the QA team. WindowTester Pro empowers developers with testing capabilities and reduces the time required to hand-code tests. This enables developers to build quality into the product early in the process because problems are found and resolved earlier in the development cycle. Using WindowTester Pro helps developers and companies drastically lower both testing time and cost—it is not uncommon to save up to 50% or more of time required to write the tests.

The tests generated by WindowTester Pro are standard JUnit tests thus they can be run within your Eclipse environment or they can be automated to run using Ant. Typically, tests are recorded on projects within your Eclipse environment. If your want to test against a deployed application, you must first import your application into your Eclipse environment.

More information about  WindowTester Pro(installation,download,sample) is available here.

Unclean shutdown detected - MongoDB 2.0.2

If you are not able to start MongoDB server then log message says

Unclean shutdown detected.
*************
Wed Mar 7 15:17:41 [initandlisten] exception in initAndListen: 12596 old lock file, terminating
Wed Mar 7 15:17:41 dbexit:
Wed Mar 7 15:17:41 [initandlisten] shutdown: going to close listening sockets...
Wed Mar 7 15:17:41 [initandlisten] shutdown: going to flush diaglog...
Wed Mar 7 15:17:41 [initandlisten] shutdown: going to close sockets...
Wed Mar 7 15:17:41 [initandlisten] shutdown: waiting for fs preallocator...
Wed Mar 7 15:17:41 [initandlisten] shutdown: closing all files...
Wed Mar 7 15:17:41 [initandlisten] closeAllFiles() finished
Wed Mar 7 15:17:41 dbexit: really exiting now

One of the reason for this issue is lock file,So fix could be removing "mongod.lock"
File location could be /srv/db/mongodb/mongod.lock

Then restart MongoDB service
/etc/init.d/mongodb start

Hope it may help to solve unclean issue

Install Opera 11.61 on Ubuntu 11.10

Simple steps to install Opera 11.61 on Ubuntu 11.10(Oneiric Ocelot)

1. Get the latest opera debian package from this link

http://www.opera.com/download

2. Run .deb file as root user

sudo dpkg -i ~/Downloads/opera_11.61.1250_i386.deb

Nginx 1.1.16 - Development version

Nginx 1.1.16 development version is available. Changes in Nginx 1.1.16 are

    * Change: the simultaneous subrequest limit has been raised to 200.

    * Feature: the "from" parameter of the "disable_symlinks" directive.

    * Feature: the "return" and "error_page" directives can be used to
       return 307 redirections.

    * Bugfix: a segmentation fault might occur in a worker process if the
       "resolver" directive was used and there was no "error_log" directive
       specified at global level.
       Thanks to Roman Arutyunyan.

    * Bugfix: a segmentation fault might occur in a worker process if the
       "proxy_http_version 1.1" or "fastcgi_keep_conn on" directives were
       used.

    * Bugfix: memory leaks.
       Thanks to Lanshun Zhou.

    * Bugfix: in the "disable_symlinks" directive.

    * Bugfix: on ZFS filesystem disk cache size might be calculated
       incorrectly; the bug had appeared in 1.0.1.

    * Bugfix: nginx could not be built by the icc 12.1 compiler.

    * Bugfix: nginx could not be built by gcc on Solaris; the bug had

More information and stable version of Nginx available here.

Scala Driver for MongoDB - Casbah

Casbah is an interface for MongoDB designed to provide more flexible access from both Java and Scala. While the current core focus is on providing a Scala oriented wrapper interface around the Java mongo driver, support for other JVM languages may come in the future.

For the Scala side, contains series of wrappers and DSL-like functionality for utilizing MongoDB from within Scala. This currently utilises the very Java-oriented Mongo Java driver, and attempts to provide more scala-like functionality on top of it. This has been tested with MongoDB 1.2.x+ and v2.x of the Mongo java driver.

Tutorial and more information available here.

Scientific Linux 6.2!

Scientific Linux 6.2 has been available for i386 and x86_64. You can download it form here.

PostgresSQL - Release 9.1.3, 9.0.7, 8.4.11 and 8.3.18!

PostgresSQL has been announced security and maintenance release of versions 9.1.3, 9.0.7, 8.4.11 and 8.3.18 last week.

Bug and performance fixes in this minor release include


* Fix btree index corruption from insertions concurrent with vacuuming
* Avoid crashing when we have problems deleting table files post-commit
* Fix recently-introduced memory leak in processing of inet/cidr
* Fix postmaster to attempt restart after a hot-standby crash

Download and release announcement available here.