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Objective 7.1 Please comment

Wasim Ayoubi
Ranch Hand

Joined: Nov 21, 2004
Posts: 46
7.1 Describe at a high level the basic characteristics, benefits and drawbacks of creating thin-clients using HTML and JavaScript and the related deployment issues and solutions.

7.1.1 Basic Characteristics:

Browsers are the thinnest of clients; they display data to their users and rely on servers for application functionality.

Browser clients download documents from a server. These documents contain data as well as instructions for presenting that data, written in a presentational markup language such as Hypertext Markup Language (HTML). A presentational markup language allows a single document to have a reasonable presentation regardless of the browser that presents it.

7.1.2 Benefits:

Browsers have a couple of strengths that make them viable enterprise application clients.
1. They offer a familiar environment. Browsers are widely deployed and used, and the interactions they offer are fairly standard. This makes browsers popular, particularly with novice users.
2. Browser clients can be easy to implement. The markup languages that browsers use provide high-level abstractions for how data is presented, leaving the mechanics of presentation and event handling to the browser.


7.1.3 Drawbacks:

The trade-off of using a simple markup language, however, is that markup languages allow only limited interactivity. For example, HTML's tags permit presentations and interactions that make sense only for hyperlinked documents. You can enhance HTML documents slightly using technologies such as JavaScript in combination with other standards, such as Cascading Style Sheets (CSS) and the Document Object Model (DOM). However, support for these documents, also known as Dynamic HTML (DHTML) documents, is inconsistent across browsers, so creating a portable DHTML-based client is difficult.

7.1.4 Deployment Issues:
Browser clients are attractive for a couple of reasons.

1. They require minimal updating. When an application changes, server-side code has to change, but browsers are almost always unaffected.
2. They are ubiquitous. Almost every computer has a Web browser and many mobile devices have a micro browser.


Wasim Ayoubi<br />SCJA1.0(BETA), SCJP1.4, SCWCD1.4<br />Next ???
Andrew Monkhouse
author and jackaroo
Marshal Commander

Joined: Mar 28, 2003
Posts: 11437
    
  85

Hi Wasim,

In addition:

7.1.2 Benefits:

A thin client based on a web browser front end can be deployed on low end hardware (think 386 instead of Pentium IV).

Regards, Andrew


The Sun Certified Java Developer Exam with J2SE 5: paper version from Amazon, PDF from Apress, Online reference: Books 24x7 Personal blog
Swapnil Sonawane
Ranch Hand

Joined: Jan 02, 2008
Posts: 190
Additionally,

JavaScript code cannot do any of the following:

� use printers or other devices on the user's system or the client-side LAN
� directly access files on the user's system or the client-side LAN ; the only exception is the access to the browser's cookie files.
� directly access files on the Web server.
� implement multiprocessing or multithreading.
� the user can always disable JavaScript.


Swapnil S. Sonawane<br /> <br />B.Tech (Expected May 2009)<br />Computer Science, NIT Durgapur, India<br />SCJA 1.0
Cameron Wallace McKenzie
author and cow tipper
Saloon Keeper

Joined: Aug 26, 2006
Posts: 4968
    
    1

Don't forget that fact that JavaScript can simply be turned off.

On my own website, about 2% of people have JavaScript disabled, and 3% have Java disabled.
Website Statistics for HibernateMadeEasy. com and SCJA .com

-Cameron McKenzie
[ May 14, 2008: Message edited by: Cameron Wallace McKenzie ]
Swapnil Sonawane
Ranch Hand

Joined: Jan 02, 2008
Posts: 190
That was the last point in my post
[ May 14, 2008: Message edited by: Swapnil Sonawane ]
Cameron Wallace McKenzie
author and cow tipper
Saloon Keeper

Joined: Aug 26, 2006
Posts: 4968
    
    1

Ooops...Read the first post, but only skimmed through the replies.

-Cameron
 
Don't get me started about those stupid light bulbs.
 
subject: Objective 7.1 Please comment