Thursday 19th of January 2017 01:53:31 PM

Web-based applications are similar to app servers, except for one thing: Web-based applications don't have client apps, instead they use web browsers on the client side. They generate their front ends using HTML, which is dynamically generated by the web-based app. In the Java world, Servlets are best suited for this job.

Web-based apps might themselves rely on another app server to gather information that is presented on the client web browser. Also, you can write Servlets that get information from remote or local databases, XML document repositories and even other Servlets. One good use for web-based apps is to be a wrapper around an app server, so that you can allow your customers to access at least part of the services offered by your app server via a simple web browser. So web-based apps allow you to integrate many components including app servers, and provide access to this information over the web via a simple web browser.

Web-based apps are very deployable, since they don't require special Java VMs to be installed on the client side, or any other special plug ins, if the creator of the web-based app relies solely on HTML. Unfortunately, this can restrict the level of service that can be offered by a web-based app when compared to the functionality offered by custom clients of an app server, but they are a good compromise when it comes to providing web-based access to your information. In fact, in a real world scenario, both a web-based app and app server may be used together, in order to provide your customers access to their information. In an Intranet setting, you might deploy the clients that come with the app server, and in an Internet setting it would be better to deploy a web-based app that sits on top of this app server, and gives your customers (relatively) limited access to their data over the web (via a simple web browser).

Web-based apps and app servers integrate very well, and this is another reason why Java and XML make a powerful combination for developing systems that give your customers access to their information from anywhere, using any browser over the web. In the future, you can imagine various different web-based apps servicing different kinds of clients, e.g. web browsers on desktops, web browsers on PDAs, and web browsers on all kinds of different consumer electronics devices. By keeping your information structured in a pure way (by using XML), and by allowing access to this information through app servers, you can write many different web-based apps that render this information by customizing it uniquely for each different device that is allowed access to this information. This is more a more scalable solution that storing all this information in web pages, even if these web pages are dynamically generated. So you can have one app server that stores all the data in XML format. You can write a web-based app (which sits on top of this app-server) that allows PalmPilots to access this information over the web. You can write another web-based app (that also sits on top of the same app server) that allows conventional web browsers to access this information over the web. XML and Java have the potential to make this truly platform independent and device independent computing a reality.

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Cascading Style Sheets: The Definitive GuideSearch this book

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Index: O

oblique text: 5.4.1. Fonts with Style
octothorpe (#) preceding ID selectors: 2.3.2. ID Selectors
offsets (see side-offset properties)
CSS implementation in: 1.3.2. Implementations
padding and: 7.5.4. Padding: Known Issues
padding values, negative: 7.5. Padding
operating system, colors and: 10.5.2. Colors
order sorting: 2.8. The Cascade
ordered lists: 7.7.1. Types of Lists
7.7.2. List Item Images
origin image: Length values
origin sorting: 2.8. The Cascade
origins: 2.8. The Cascade
orphans property: 10.8.1. Paged Media
outline properties: 10.5.3. Outlines
overflow: 9.1.4. Content Overflow and Clipping
overflow-clip property: Overflow clipping
overflow clipping: Overflow clipping
overflow property: Overflow
elements, altering: 9.5. Stacking Positioned Elements
floated elements, preventing: 8.3.1. Floating: The Details
margins (see collapsing margins)
text, preventing: 8.4.3. Managing the Line Height of Inline Elements
overlining: 4.1.6. Text Decoration
overriding previously declared values: 11.1.3. Case 3: Putting a Magazine Article Online

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you're trying to do things like add borders to an inlineelement. Let's say you want to put 5-pixel borders around anyhyperlink:

A:link {border: 5px solid blue;}

If you don't set a large enough line-heightto accommodate the border, it will be in danger of overwriting otherlines, as shown in Figure 8-62.

Figure 8-62

Figure 8-62. Inline borders can be overlapped

shown in
Figure 5-27, and the only difference thereis a single point in size.

Figure 5-27

Figure 5-27. Same font, same style, different sizes

There isn't much that can be done about this, unfortunately,save better font handling by operating systems. Usually, the italicand oblique fonts look exactly the same in web browsers.

Still, font-style can be useful. For example, itis a common typographic convention that a block quote should be

6.1. Colors

There is really only one type of color in CSS, and that'splain, solid color. If you set the background of a page to bered, then the entire background will be the sameshade of red. This is no different than what's been possible inHTML up until now, of course. When you declare<BODY LINK="blue"VLINK="blue">, you probably expect that all

In the meantime, however, here's the script:

<SCRIPT LANGUAGE="JavaScript1.2">
var agt = navigator.userAgent.toLowerCase(  );
var is_major = parseInt(navigator.appVersion);
var is_nav = ((agt.indexOf('mozilla') != -1) &&
(agt.indexOf('spoofer') == -1) &&
(agt.indexOf('compatible') == -1));
var is_nav4 = (is_nav && (is_major == 4));

<DIV CLASS="navbar">icons</DIV>

Now all we need is the style .navbar{background: green;} andwe're set. Or are we?

Not quite, no. In the old page, the navigation bar was separated slightly fromthe main display, but ran right up against the sidebar, thereby