Chapter 1: Overview of Technologies

Overview

Developing applications for the Web is a complex process. The number of programming languages, Application Programming Interfaces (APIs), frameworks, and development platforms is much higher than it has been in years past and it continues to grow at a lightning pace. IT departments wanting to maintain their competitive advantage are asked to evaluate and embrace new technologies faster than ever before. This leads to shorter development times for projects and shorter times for developers to absorb new technologies. These factors, coupled with the fact that developers are increasingly called upon to have a working knowledge of and provide input on things such as database design, networking, development methodologies, code-generating tools, Java frameworks, and source code management, has led to a crisis in the development world where developers don t have enough hours in the day to learn all of the aspects of the tasks they need to know to be productive members of their IT departments. Luckily for Oracle developers, Oracle has provided a series of products that allows you to create and test applications quickly, interface with the Oracle database seamlessly, and deploy those applications to the Web securely and with minimal effort. Oracle s development and Application Server products have the added advantage of maturity: they are stable, proven technologies used in a wide range of production environments throughout the world.

At the core of your development efforts is the Oracle Application Server, sometimes incorrectly referred to as a web server (web servers are a subcomponent of the Application Server). The Application Server takes requests from a client application, most likely a web browser such as Internet Explorer or Netscape Navigator, processes the requests , and returns the results. It then, depending on the type of request it receives, can call other programs or speak to databases to satisfy the client s request. The Application Servers uses Transmission Control Protocol/Internet Protocol (TCP/IP), the protocol defining the rules for establishing connections between computers and HyperText Transfer Protocol (HTTP) to control the communication between a web browser and a web server.

Oracle Application Server 10 g is a product designed to meet all of the challenges your organization faces when putting your applications on the Web. While the details of installing and administrating the Application Server are beyond the scope of this book, all Oracle developers can benefit from an understanding of the basic framework of web development and Oracle s solutions for each of these framework pieces. In the language used in Oracle s documentation, the implementation of these solutions is called services , and services are integrated into the Application Server 10 g product stack.

For more information regarding installation and administration of Oracle Application Server 10 g , see the Oracle Application Server 10 g Administration Handbook by John Garmany and Donald K. Burleson (Oracle Press, 2004).

The amount of tools and services provided by Application Server 10 g can seem overwhelming. You are certainly not required to implement every service provided by Application Server 10 g; services that are installed and configured but not used waste resources, so choose your installation options carefully . Organizations can pick and choose those services they wish to exploit. Even if a particular service is not selected during installation, it is possible to go back and add that functionality to Application Server 10 g at a later date without affecting your current production setup. This provides tremendous flexibility as developers can change direction without abandoning work performed up to that point.

A good example of this would be the Oracle Forms Server that is part of Application Server 10 g . This service allows you to take existing Oracle Forms and serve them up over the Web. Perhaps your organization has begun by using Oracle Portal to quickly develop some forms and reports that are published over the Web to your employees . This initial project has proven to be so popular that the decision has been made to move Oracle Forms, Oracle Reports, and Oracle Discoverer worksheets (which have richer feature sets than their equivalent components in Portal) to the Web and to integrate some of those components with Portal. An administrator can reconfigure Application Server 10 g to add the necessary functionality without affecting any of the work performed up to this point.

By doing this, your organization can move to a web-based model without losing the time and effort already invested in Forms, Reports, or Discoverer development. As your needs grow, it is possible to augment your development efforts with PL/SQL server pages (PSPs) or a tool such as JDeveloper to implement technologies like JavaServer Pages (JSPs), Enterprise JavaBeans (EJBs), Struts, or Java applets. As the site traffic grows, you can increase performance by implementing the Oracle Web Cache service to cache the most heavily used pages. Power users can create their own ad-hoc reports using Discoverer. You can expand your Portal to integrate content, web-based components (such as forms, reports, or XML-based portlets) and content from external sites with a minimal investment in development and design time. The feature set of Application Server 10 g can tackle virtually any development challenge organizations face today.

The architecture of Application Server 10 g allows you to scale by adding more Application Servers (called mid-tiers in Oracle s documentation) and more Web Cache servers. You can even allow others to incorporate your content through the use of XML and Enterprise JavaBeans. All of this is managed through a single web interface, the Oracle Enterprise Manager Application Server Control.

One could argue that as a developer, it is not necessary to understand the architecture of Application Server 10 g . While we have met many developers with this philosophy, we strongly urge you to make the effort to understand the fundamentals of how the Application Server does its basic functions. The administrative details of Application Server 10 g will probably be handled by a systems administrator or a DBA, but, as we ll see in later chapters, there are many steps that fall upon the developer s shoulders as you test and implement your development efforts. A basic knowledge of Application Server 10 g ˜s structure is important and will make your job easier moving forward.