Web-Based Systems Defined


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Section 0: Module Objectives or Competencies
Course Objective or Competency Module Objectives or Competency
The student will be able to explain the differences between web-based systems and conventional systems. The student will learn what web-based systems are and why they are considered systems.

Section 1: Web-based Systems

In the early days of the web (from around 1990 to 1995), websites consisted of little more than a set of linked hypertext files that presented information using text and limited graphics.

Over time, HTML was augmented by development tools and technologies like XML and Java that enabled web developers to provide both client-side and server-side computing capability along with content.

A web-based application is any program that is accessed over a network connection using HTTP, rather than existing within a device’s memory.

Today, web applications have evolved into sophisticated computing tools that not only provide stand-alone functionality to the end user, but also have been integrated with corporate and governmental databases and applications.

Here is a review page to accompany my notes.


Section 2: Systems?

Web applications are computer software in the sense that they are a collection of executable instructions and data that provide both information and functionality for end users.

The implication, therefore, is that it's reasonable to expect that we can develop web applications by heeding some, if not all, of the lessons we've learned during the many decades we've built conventional computer-based systems.

It's also reasonable to assume that we'll encounter many, if not all, of the problems (both cultural and technical) that are common to traditional development approaches.

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What is a client-server application?

Client-server describes an application architecture in which the client requests an action or service from the provider of service, the server. Consider a Web browser and a Web server. When you address a URL in the browser window, it (client) requests a page from a Web server. The server returns an html page to the client, which parses the page (data) and displays it on your computer.

When developing a client-server application, like the Web browser and Web server, you need to consider how you are going to handle developing your application in a team environment and how you are going to handle long-term maintenance. Developing client-server applications parallels developing modular programs. Modular programming separates large applications into smaller constituent pieces to ease development in teams and provide better maintainability. In a client-server application, a module does not have to be part of the same program or even run on the same computer. Each modular function can run on a different device.

Slient-server Architecture diagram

2. How does a client perform?

Client programs request service from a server by sending it a message. Referring back to the Web example, a Web browser is a client we use every day to request Web pages. For example, when you clicked the link to read this article, your browser sent a message to a Web server in Austin, TX. In response, your browser received the html page you are now reading. A Web browser represents many client programs, which manage the graphical user interface (GUI) or display portion of an application; determining the presentation of the service provided by an application.

3. What is a server's function?

Server programs process client requests by performing the tasks requested by clients. For example, in a Web browser the Web server returns the html page requested by the client. But client requests and server programs are not always so simple. Consider a more complicated application in which you buy a product on a Web page. In this case, the client informs the server what you are purchasing and the server updates a database with the purchase request. Then, the server informs the client that the order has been placed.

Servers are generally passive as they wait for a client request. During these waiting periods servers can perform other tasks or perform maintenance. Unlike the client, the server must continually run because clients can request service at any time. Clients on the other hand only need to run when they require service. Many server applications allow for multiple clients to request service. For example, while you are reading this page others interested in client-server programming could also request and read the same Web page.

Original Article was once on the National Instruments site at http://www.ni.com/white-paper/4431/en/.

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What is network intensive?

A network intensive application is any application that requires a significant proportion of a server's available bandwidth.