Hadoop MapReduce

Introduction
HDFS stores file in multiple equal large size block e.g. 64 MB, 128 MB etc. and MapReduce framework access and process these files in distributed environment.
The MapReduce framework works on key-value pairs, it has two key part Mapper and Reducer.Map Reducers read file and split and pass to Mapper. Mapper set the input as key-value pairs and pass to the intermediate for sorting and shuffling. Reducer takes the key and list of value, process and writes to the disk. Continue reading

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Apache Hadoop Setup

Hadoop 2.x is based on YARN architecture, which uses ResourceManagaer and ApplicationManager. ResourceManagaer manage recourses across cluster and Application Manager manages job life cycles. Continue reading

Grails Services

Services

Grails Service uses to separate your business logic from the other layer or component. Services are named in the format SomeNameService.groovy and placed in the directory /grails-app/services/. Services can make use of dependency injection features, and you can easily call these services from within controllers. Continue reading

Grails – GSP

GSP

Grails uses GSP for the presentation tier. The Groovy in Groovy Server Pages not only identifies the underlying technology, but also the language you can use if you want to write a quick scriptlet or two. Groovy Taglib and partial templates give you a more sophisticated way of sharing code and behavior across Web pages. Continue reading

Grails Understanding

Grails

Grails is a web framework based on Groovy and Java which can be deployed into existing Java web servers, e.g. Tomcat or Jetty. Its scaffolding capabilities let you create a new project within a few minutes. Grails is based on the “convention over configuration” idea which allows the application to auto-wires itself based on naming schemes (instead of using configuration files, e.gl XML files). Continue reading