PHP 5/MySQL Programming- P62 potx

Each page that the user sees is a combination of three different HTML pages: a banner, menu, and content page.. The CSS won’t take effect, but all the other HTML code will work and the u

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(Of course, the menu can be much more sophisticated, but it’s good to start

slowly In the next section you look at the sneaky (but not difficult) way the menu

HTML is coded.)

I kept the code very simple, but of course you can (and should) improve it

how-ever you wish Add background graphics, borders, or improved text Put the

menu across the right or top

It’s important that I used percentage measurements in this element, because

I don’t know the user’s screen resolution By indicating position and width in per-centages, I have a style that works well regardless of the browser size.

The item class is the other important CSS element in this code sample It’s

another specialized span dedicated to placing the Web page’s main content The

itemclass works well with the menuPanelclass It is placed a little to the right of

the menu panel and takes up most of the remaining screen space Once again,

the actual style is quite simplistic and you probably want to spruce it up

Inspecting the Menu System

The real key to the simpleCMSis the way it’s used Each page that the user sees is

a combination of three different HTML pages: a banner, menu, and content page

The simpleCMS.phpprogram puts these three elements together according to a

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What about browsers that don’t support CSS? Some would argue that a

table-based approach to layout (as PHP-Nuke and many other CMS tools use) would

work across more browsers than this CSS-centric approach While it’s true

some older browsers support tables but not CSS, tables have their own

prob-lems as page layout tools

Tables were never really designed for that purpose, so to get a layout exactly

like you want, you often have to build a Byzantine complex of tables nested

within tables, with all sorts of odd colspan tricks and invisible borders

The positionable CSS elements were invented partially to provide a simpler,

more uniform solution to page layout headaches The browsers that don’t

sup-port CSS still display everything encoded in a CSS-augmented page The CSS

won’t take effect, but all the other HTML code will work and the user can use

the page

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specific style sheet For this example, presume that the CSS style and banner remain the same for every system-displayed page (This is usually the behavior you want.)

You never directly link to any of the pages in your system Instead, you link to the simpleCMS.phpprogram and pass the content file (and menu file, if you wish) you want displayed Recall that simpleCMS requires two parameters Most PHP pro-grams get their parameters from HTML forms, but you may remember from chap-ter 2, “Using Variables and Input,” that paramechap-ters can be sent through the URL via the GET protocol You can make any page display as an element of your CMS

by calling it as a parameter

To clarify, take a look at the menu.htmlcode:

<ul>

main</a>

</li>

classes</a>

</li>

links</a>

</li>

software</a>

</li>

media</a>

</li>

</ul>

Notice the trick? The first link refers to a page called default.html Rather than directly linking to default.html, I linked to simpleCMS and passed the value default.html as the content parameter When simpleCMS runs, it places the default banner (top.html) and the default menu (menu.html), but places the con-tents of default.htmlin the new page’s itemarea I didn’t send a menu parame-ter, but I could have, and it would have placed some other page in the menu area

In short, you can place any page in the menu area by assigning its URL to the menu parameter; you can assign any page to the itemarea by assigning its value

to the content parameter Any page you want displayed using the CMS must be

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called through a link to the CMS program, which pastes together all the other

pages You can place any HTML into any of the segments, but your menu usually

goes in the menu area and is usually written only with links running back

through the CMS

You can create a reasonably sophisticated multilevel CMS with only this very

basic program by experimenting with different menus, CSS styles, and banners

You might wonder why I didn’t show you the source code for the CMS top and con-tent areas There’s nothing at all unusual about these pages, so I didn’t think it was necessary Generally, you write the top to be banner-like (very simple, designed to cover the entire width of the page, but just a short height) The pages you want to display in a CMS don’t need header areas, titles, or page-level CSS definitions, because many are ignored in this multipage document The CMS dictates these meanings for the entire composite page.

Improving the CMS with XML

Although the simpleCMSpresented earlier is extremely powerful, it is limited to

only two parameters It would be great if you could control even more

informa-tion on every pass through the CMS It also would be nice to determine the page

title, CSS style, top area, menu page, and body on every pass through the system

However, the GETmethod approach used in simpleCMS quickly becomes

cumber-some when you’re sending more than one or two parameters

The GET method allows limited amounts of data to be passed The URLS get

tedious when you have that much information to send Most CMSs use an

alter-native method of storing the information about intended page values A lot of

CMSs (like PHP-Nuke) use the full power of relational databases This is a

wonder-ful way to go, but it can be somewhat involved for a basic demonstration There

is a more-powerful alternative than basic parameter passing, although it’s not

quite as intimidating as a relational data structure

Introducing XML

eXtensible Markup Language, or XML, has become a major topic of conversation

in the software industry in the last few years It isn’t just a language, but a

flex-ible and sensflex-ible alternative for manipulating data It’s really a language for

describing languages

XML feels a lot like HTML (because they’re related) but it’s quite a bit more

flexi-ble In a nutshell, XML allows you to use HTML-style syntax to describe anything

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For example, if you want to talk about pets, you could use the following code:

<?xml version=”1.0” encoding=”utf-8” ?>

<pets>

<cat>

<color>tabby</color>

<breed>shorthair</breed>

</cat>

<dog name = “Muchacha”

color = “brown”

breed = “mutt” />

</pets>

As you look at this fragment of (entirely fictional) XML code, you see an unmis-takable resemblance to HTML XML uses many conventions that are familiar to HTML developers, including nested and closing tags and attributes The most sig-nificant difference is the tags themselves HTML tags are specifically about Web page markup, but XML tags can describe anything As long as you have (or can write) a program to interpret the XML code, you can use HTML-like code to describe the information

Working with XML

XML has a number of data-management tool advantages XML files can be stored and manipulated as string data and ordinary text files This makes it easy to duplicate data and move it around the Internet XML data is somewhat self-documenting You can look at XML data in a text editor and have a good idea what it means This would be impossible if the data were stored in a database table or proprietary format Most languages have features that allow you to eas-ily extract data from an XML document even if you don’t know exactly how the document is formatted

Understanding XML Rules

XML is very similar to HTML, but it is not quite as forgiving on syntax Remember these rules when creating an XML document:

• XML is case sensitive Most tags use lowercase or camelCase (just like PHP)

<pet> and <PET>are two different tags

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• All attributes must be encased in quotation marks In HTML, quotation

marks are always optional In XML, almost all attribute values should

be quoted For example, <dog name = muchacha>is not legal in XML

The appropriate expression is <dog name = “muchacha”>

• All tags require an ending tag HTML is pretty forgiving about whether

you include ending tags XML is much more strict Every tag must have

an ending tag or indicate with a trailing slash that it doesn’t have an end

In the earlier example, <cat>has an ending </cat>tag I defined dogto

encase all its data in attributes rather than subtags, so it doesn’t have an

explicit ending tag Notice how the dogtag ends with a slash (/>) to

indi-cate it has no end tag

Examining main.xml

The second CMS system in this chapter uses XML files to store page information

To see why this could be useful, take a look at the XML file that describes my

main page in the new XML-based content management system (XCMS):

<?xml version=”1.0” encoding=”utf-8”?>

<cpage>

<css>menuLeft.css</css>

<menu>menuX.html</menu>

<content>http://www.cs.iupui.edu/~aharris/default</content>

</cpage>

The entire document is stored in a <cpage></cpage>element cpage represents a

CMS page Inside the page are five parameters Each page has a title as well as

URLs to a CSS style, top page, menu page, and content page The XML succinctly

describes all the data necessary to build a page in my CMS I build such an XML

page for every page I want displayed in my system It is actually pretty easy

because most of the pages are the same except for the content

It would be even easier in a real-world application, because I would probably build an editor to create the XML pages automatically That way the user would never have to know he was building XML Sounds like another great end-of-chapter project!

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