Enhance the functionality of a Web page

1. Enhance the functionality of a Web page • Key points •  Server-Client Interaction • Forms • Invoke a CGI script • Pass parameters to a CGI script • Client side scripts

2. Server-Client Interaction • Server push -- the server sends down a chunk of data; the browser display the data but leaves the connection open; whenever the server wants it sends more data and the browser displays it, leaving the connection open; at some later time the server sends down yet more data and the browser displays it; etc. • Client pull -- the server sends down a chunk of data, including a directive (in the HTTP response or the document header) that says "reload this data in 5 seconds", or "go load this other URL in 10 seconds". After the specified amount of time has elapsed, the client does what it was told -- either reloading the current data or getting new data.

3. <META HTTP-EQUIV="Refresh" CONTENT=1> <title>Document ONE</title> <h1>This is Document ONE!</h1> Here's some text. <p> <META HTTP-EQUIV="Refresh" CONTENT="12; URL=http://foo.bar/blatz.html"> Client pull

4. Client Pull • Server sends data + including a directive • ("reload in X seconds", or "go get Y in X seconds") • Client wait then do as told • Example 2: Switching between two windows

5. Following in the tradition of the standard "multipart/mixed", "multipart/x-mixed-replace" messages are composed using a unique boundary line that separates each data object. Each data object has its own headers, allowing for an object-specific content type and other information to be specified. The specific behavior of "multipart/x-mixed-replace" is that each new data object replaces the previous data object. The browser gets rid of the first data object and instead displays the second data object. A "multipart/x-mixed-replace" message doesn't have to end! That is, the server can just keep the connection open forever and send down as many new data objects as it wants. The process will then terminate if the user is no longer displaying that data stream in a browser window or if the browser severs the connection (e.g. the user presses the "Stop" button). We expect this will be the typical way people will use server push. The previous document will be cleared and the browser will begin displaying the next document when the "Content-type" header is found, or at the end of the headers otherwise, for a new data block. The current data block (document) is considered finished when the next message boundary is found. Together, the above two items mean that the server should push down the pipe: a set of headers (most likely including "Content-type"), the data itself, and a separator (message boundary). When the browser sees the separator, it knows to sit still and wait indefinitely for the next data block to arrive. Server Push

6. Server Push • #!/bin/sh • echo "HTTP/1.0 200" • echo "Content-type: multipart/x-mixed-replace;boundary=---ThisRandomString---" • echo "" • echo "---ThisRandomString---" • while true • do • echo "Content-type: text/html" • echo "" • echo "<h2>Processes on this machine updated every 5 seconds</h2>" • echo "time: " • date • echo "<p>" • echo "<plaintext>" • ps -el • echo "---ThisRandomString---" • sleep 5 • done

7. Server push • Server sends data; browser display data • keep connection open; • server wants more data, browser displays • leaving the connection open; … • Example: Stock broker’s terminal • More efficient, bandwidth hungary, adapted to individual

8. Forms • One of the fundamental elements of interaction • Use: sending data to sever for processing • Syntax • <form action=script_url method=get (or post)> • <input type=xxx name1=yyy value1=zzz> • … • <input type=submit name=submit> • </form>

9. Pass parameters to a CGI script • Syntax • Script_url?name1=value1&name2=value2… • Role of Scripts • Major: forms, popups • Minor: counter, clock, etc.

10. Web site promotion • Web site promotion or SEO (Search Engine Optimisation) or web-positioning, although it has many names, its objective remains the same - improve your position on search results to get a huge source of traffic without spending large sums of vital capital in advertising expenses. • Key points for this topic • Search engines and directories • Site and page submission • Page optimization • Doorway and hallway pages • Beyond Web site • Rank pushing service and software

11. Search engines and directories • Search engine is a software system that collects and indexes Web pages and respond to queries with organized results. • Top three search engines: • Google http://www.google.com • Yahoo http://www.yahoo.com • Ask Jeeves http://www.askjeeves.com • Directory is a system that collects Web sites and organizes them in a hierarchical structure. e.g. Yahoo

12. Site and page submission • Submission to a directory • The following sentence is what I copied from a company’s homepage: The problem is that getting there and staying there can be too expensive for many businesses, especially if you hire an optimization professional. That's why we created Submit It! -- to give you thetools you need to succeed without breaking the bank. • Submission to a search engine

13. Avoid Spamming Searches • Avoid spamming searches • For years experts in the field of Search Engine Optimization (SEO) have attempted to determine how search engines examine, analyze and rank web pages. These experts spend incredible amounts of time experimenting, examining, observing and reverse engineering the algorithms used by search engines in order to get their (and their clients) pages to rank higher for desirable keywords and phrases. • Some of the techniques they use include: • Domain Name Spamming - A domain name can tell a spider a lot about a site, and creating thousands of them can say even more. • Guestbook Spamming - To fool some search engines into thinking there are a lot of links to a site, some unethical webmasters run special programs which create entries in thousands or even millions of guestbooks. • Keyword stuffing - Spiders look for the number of occurrences of keywords and phrases on a page to determine the subject (or subjects) of the information. Spammers can skew the results by including keywords in various places. • Log File Spamming - It's possible to take advantage of publicly available web site statistics to create the illusion of links to a site.

14. Page optimization • Keywords selection • Specific, targeted • Keywords in meta tags • Keywords frequency • Avoid keyword spamming • Keywords location (url, title, top, bottom, middle, url, alt) • Page length

15. <html xmlns = "http://www.w3.org/1999/xhtml"> <head> <title>Internet and WWW How to Program - Welcome</title> <!-- <meta> tags provide search engines with --> <!-- information used to catalog a site --> <meta name = "keywords" content = "Web page, design, XHTML, tutorial, personal, help, index, form, contact, feedback, list, links, frame, deitel" /> <meta name = "description" content = "This Web site will help you learn the basics of XHTML and Web page design through the use of interactive examples and instruction." /> </head> Keywords in meta tags Demonstrate a “keywords” meta element. The contents attribute of such a meta element provides search engines with a list of words that describe a page Demonstrate a “description” meta element. The content attribute of such a meta element provides a three- to four-line description of a site, written in sentence form. Search engines also use this description to catalogue your site and sometimes display this information as part of the search results.

16. Doorway and hallway pages • Functions: Optimized pages (for search engines) leading to home page. • Doorway pages, also called gateway pages or hook pages, are no more than any page of a site which has keywords that may be found in a search.  By entering your site from a search engine at such a page, visitors experience the page as a 'doorway' to your web site. • A hallway page is like an index of urls that you want a search engine to spider. It has the primary function of acting as an list of all the pages you want a spider to 'crawl' and index for you. The reason we use hallway pages, is that many search engines have a limit upon how many direct submissions you make within a set time period (sometimes just 1 page per day). By submitting a hallway page, you are indirectly submitting every page that is listed on it. • Advantages: • do not affect existing design • compliment to dynamic sites • individually tuned for unique keyword

17. Beyond your own Web site • Search engine updating • Keyword ranking • Link popularity • Advertising • Online: email, banners, links • Offline: magazines, newspaper

18. Rank pushing service and software • http://www.webposition.com