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Making Database backed Websites

Making Database backed Websites. Session 1 Building a simple website by hand. How does the web work?. A web-server waits for requests from a browser ( web-client ) When you go to a site your browser sends a request to the web server It sends back the HTML for the page

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Making Database backed Websites

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  1. Making Database backed Websites Session 1 Building a simple website by hand

  2. How does the web work? • A web-server waits for requests from a browser (web-client) • When you go to a site your browser sends a request to the web server • It sends back the HTML for the page • Your browser parses the page looking for other resources it needs (eg images) • It requests and receives the additional resources

  3. HTML • Originally designed as a SemanticMarkup Language • Consists of Head and Body • Head contains information about the web page (eg title) • Body contains the content of the page itself

  4. Tags • HTML tags markup parts of the page as being head, body, a title, bold, etc. • Tags look like… • <head> ...some stuff… </head> • Some tags also have attributes • <img src=“foo.gif”> • Note, in HTML not all tags close

  5. A short page • <html> • <head> • <title>A short page</title> • </head> • <body> • Some content for our short page • </body> • </html> • Note: The indenting is not important, but it makes it easier to see the structure of the document.

  6. The major tags • <HTML> • <head> • <title> • <body> • <h1> <h2> <h3> <h4> <h5> <h6> • <p> <img src=“foo.gif” alt=“a foo”> • <table> • <tr> • <td> <th> • <a href=“foo.html”> <a name=“bar”> • <!-- comment -->

  7. Linking pages together • <html> • <body> • <ul> • <li><a href=“stuff.html”>Stuff</a></li> • <li><a href=“bother.html”>Bother</a></li> • </ul> • </body> • </html> • This page will be have links to a page called stuff.html and another called bother.html

  8. Blue Peter moment • Here’s one I prepared earlier… • Errr…why does it look awful? We need some style!

  9. Getting it to look good • There are two broad approaches… • Using HTML as a layout language (a Bad Thing) • …or… • Using Semantic Markup (a Good Thing)

  10. Non-Semantic Markup • <b> <i> • <font> • <table> when used for layout • Widely used (even by me), but considered a “Bad Thing”. Don’t do it…use semantic markup instead

  11. Semantic Markup • Use markup to denote the meaning of parts of the document. • i.e. Which part is the title, which parts are headings • Then use stylesheets to control the appearance. • <strong> <em> <span> <div>

  12. Style Sheets • h1 { • font-family: Helvetica; • color: #008800; • background-color: #ffffff; • text-decoration: underline; • } • div.special { color: #bbbbbb; }

  13. Style Sheets • Inline styles – the <style> tag • <style> • h1 { color: #ff0000; } • <style> • External Style sheets <link> tag • <link rel=“stylesheet” type=“text/css” href=“/styles/style.css”> • External styles generally are generally better, unless you want to add one extra style to a specific page, that’s never going to be used elsewhere… Why?

  14. Colours • Look like #ff6790 (which is a pinkish colour) • Made up of Red, Green and Blue • #RRGGBB • Unfortunately in hexadecimal, (base 16).

  15. Regions • <div class=“special”> • here’s some text in a grey region • </div> • <span class=“weird”>Freaky</span> • The appearance of the regions is defined by style sheets.

  16. Site layout strategies • Addressing types • Absolute <a href=http://www.foo.com/bar.html> • will work from anywhere. The only option for linking to pages on another site • Relative <a href=“bar.html”> • assuming that the page with the link is in the same directory. Will stop working if you move either of the pages. • RootRelative <a href=“/bar.html”> • assuming the page with the link is on the same server. Will work so long as the target page is not moved. • Since sites tend to have lots of links within the site Root Relative is very useful.

  17. Site layout strategies • Use folders to group related pages within a site. The URL can be a useful navigation tool for experienced surfers. • Put images that are used all over the site in one place – often in /images/ • Site wide style sheets in one place – say /styles/ • Resources that are only used for part of a site in subfolders.

  18. Why does site layout matter? • If you’ve written 5 webpages, it probably doesn’t. • If you’ve written 5000 and you decide you want to change something… bad layout will toast you. • Bad separation of style from content will also toast you since you’ll have to update the style elements on every page.

  19. Forms! • This is where it gets exciting… • <form action=“dosomething.php” method=“get”> • <input type=“button” name=“foo” value=“bar”> • <input type=“text” name=“baz” value=“wibble” size=“20”> • <input type=“checkbox” name=“c1” value=“c1on”> • <textarea rows=“6” cols=“40”> • Some text • </textarea> • </form>

  20. So where does the data go? • We’ll come to that in the final week!! • For now just use the script “echo.php”

  21. Questions? Presentation online at… http://people.surfaceeffect.com/pete/ tech/howitworks/dbwebsites/

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