Architecture Blog

Framework

Admin — Sat, 04 Oct 2008 12:51:48 GMT

What is a Framework?

Can I say JDK API and J2EE API are the Frameworks?

See, how java and j2EE is made up of -

Servlet API

EJB API

Persistence API

Net API

File System API

JDBC API

What are all above?

All these are basically set of interfaces and classes. Some classes are abstract, some are fully implemented.

Writing Servlet

When we write an Http Servlet by extending HttpServlet, we override doGet and doPost methods. What is the need? This is a guideline from framework. Framework says you need to implement these methods for handing the request and response as per your need.

Struts 1.1

There is a Struts API (set of interface and classes) from apache. It is composed of ActionServlet, Action, ActionForm, and ActionMappings etc.

We say struts as a Web Presentation Framework. Before this how do we write Web Presentation Part of the Applications?

We create multiple servlets which handle multiple requests and post request handling we route to the next servlet or the presentation JSP.

So what does struts as a Framework replaced–

Do not create N – servlets for handling N requests, instead configure one common servlet(ActionServlet as part of Struts Framework) which will be a single point of receiver for any request. To implement this each request action have a common (*.do) and this is mapped to a ActionServlet Mapping.

Now ActionServlet will receive the request, get the URI (say LoginAction.do) and ping the struts config file to see who is the Handler(Action Class) for this.

When we write the Action Class – Struts framework mandate us to –

Extend from Action(Struts Framework Class) - Guideline from a Framework

Wtite execute method (Guideline from Framework)

All actions needs to be configured in the struts-config.xml file - Guideline from struts.

Understanding Tenets of SOA

Admin — Thu, 10 Jul 2008 07:13:15 GMT

The acronym SOA is for Service Oriented Architecture. To define a service is simple terms , a service is a program that can be interacted with via well-defined message exchanges. Services must be designed for both availability and stability.

Service Orientation - An Overview of what it is

Admin — Thu, 10 Jul 2008 07:09:16 GMT

Service-orientation is, as per industry, the correct way to build maintainable, robust, and secure applications. When developing a service-oriented application, you decouple the service code from the technology and platform used by the client. Even securing the transfer of the message itself from the client to the service is also outside the scope of the service, and so is authenticating the caller. The service may do its own local authorization as per the requirements

JDBC Database Drivers

Admin — Wed, 25 Jun 2008 18:42:51 GMT

1 The JDBC/ODBC bridge driver A piece of native C-code that translates a JDBC call to an ODBC call. Use this driver for development, not for industrial-strength application environments. Note that you have to have an ODBC database driver manager + an ODBC database driver installed on the server in addition to the JDBC/ODBC bridge.

2 Native API partly java driver A piece of native C-code that translates a java JDBC call to a native database call level API. Use this driver for development and deployment. Due to its native code, this driver can only be used by Java Applications with full computer access (i.e. not Applets).

3 JDBC-Net pure Java driver A piece of pure java code that translates an incoming JDBC call to an outgoing database Net protocol call (such as SQL*Net). Use this driverfor development and deployment. Flexible and powerful, this driver can be used by any Java component and requires only connect access to work.

4 Native protocol pure Java driver A piece of pure java code that translates an incoming JDBC call to an outgoing database native protocol call (such as Oracle CLI). Use this driver for development and deployment. This driver type is the recommended one for server-side java development unless a type 2 driver has considerable performance advantages.

EJB Transactions

Admin — Wed, 25 Jun 2008 18:20:41 GMT

ACID Properties

Atomic

Concurrent

Isolated

Durable

Transactional isolation

Dirty Read Problem

Unrepeatable Read Problem

Phantom Problem

Transactional Attributes

Message Driven Beans

Admin — Wed, 25 Jun 2008 18:17:39 GMT

Java Message Service

Message Driven Bean

Entity Beans

Admin — Wed, 25 Jun 2008 18:16:24 GMT

Entity Beans

Bean Managed Persistent Entity Beans

Container Managed Persistent Entity Beans

Session Beans

Admin — Wed, 25 Jun 2008 18:13:00 GMT

Session Beans

Session Bean Types

Stateless Session Beans

Stateful Session Beans

Writing EJB

Admin — Wed, 25 Jun 2008 18:11:29 GMT

Remote Interface

Local Interface

Home Interface

Local Home Interface

Bean Class

Deployment Descriptor

Vendor Specific Files

EJB-JAR File

Bean Deployment

Running the System

EJB Fundamentals

Admin — Wed, 25 Jun 2008 18:08:58 GMT

Enterprise Beans

Type of Enterprise Beans

Components of an Enterprise Bean