Nit's Cookbook

What is Liferay Portal? Liferay Portal is the world's leading open source enterprise portal solution using the latest in Java and Web 2.0 technologies. Runs on all major application servers & servlet containers,databases, and operating systems with over 700 deployment combinations. JSR 168 and JSR 286 compliant Out-of-the-box usability with over 60 portlets pre-bundled Built-in Content Management System (CMS) Built-in Collaboration suite Personalized pages for all user What are JSR 168 and JSR 286? JSR 168 and JSR 286 are Portlet Specifications They were created out of a need to have a specification for displaying multiple applications on the same page. The specs define the lifecycle of a portlet as well as its characteristics/look and feel. They standardize the way portlets are developed What is a portlet? A portlet is a web component that processes requests and generates dynamic content. The content generated by a portlet is also cal...

I bumped into this post  http://www.developersbook.com/hibernate/interview-questions/hibernate-interview-questions-faqs.php  and found it very useful. However I tweaked a few questions and answers in a way that I understand better. Hence posting it here for future reference. 1.What is ORM ? ORM stands for object/relational mapping. ORM is the automated persistence of objects in a Java application to the tables in a relational database. 2.What does ORM consists of ? An ORM solution consists of the followig four pieces: API for performing basic CRUD operations API to express queries refering to classes Facilities to specify metadata Optimization facilities : dirty checking,lazy associations fetching 3.What are the ORM levels ? The ORM levels are: Pure relational (stored procedure.) Light objects mapping (JDBC) Medium object mapping Full object Mapping (composition,inheritance, polymorphism, persistence by reachab...