1. CO1552 – Web Application Development Lecture 2 – What is the Internet?

2. The Internet Structure ISP Dial-up connection NSP Internet Backbone A worldwide network of computers linked together via the telecommunication lines. ADSL Connection NSP – Network Service Provider ISP – Internet Service provider End Users

3. The Internet - Where and When U.S. Dept of Defence wanted to develop a communications system that had inbuilt redundancy Needed to be able to operate over a distributed and changing network (to cope with partial loss of service) Led to the development of the Internet Protocol (IP) addressing and routing system Used initially for communications – e-mail Network usage was extended to Universities and some businesses In the early 1990’s the idea of the World Wide Web found a suitable home and the Internet as we know it today arrived.

4. The Web - Where and When In 1989, Time Berners-Lee and employee of the European Council for Nuclear Research (CERN), proposed the principle of the World Wide Web This built on earlier work he had done called Enquire The key points of the proposal were: A user interface that would be consistent across all platforms A scheme for this interface to access multiple document types A specification for the storage of information in documentation with references to information in other documents (hyperlinks)

5. Forerunners of the Web There are numerous other examples of ‘hypertext’ type systems (non-linear information presentation), mainly from the last century The idea of hypertext has been around since 1945 Vannevar Bush first proposed the idea of linked information in a machine he called a Memex (track down “As we may think”) In 1965, Ted Nelson coined the phrase Hypertext in relation to an idea he had called Xanadu – an ambitious project to make all the worlds literature available via computers Nelson also coined the phrase hypermedia – the idea that images could also be used to form links among information sources In 1985 Xerox Palo Alto Research Centre (PARC) developed a system called NoteCard, this was extended into a facility called HyperCard which was distributed via Apple Macintosh computers

6. The first Graphical Browser In the early days of the Web, information was retrieved via textual command line interfaces In 1993 an undergraduate student from Illinois led a team that developed the first Graphical Interface for the Web, this was called MOSAIC Mosaic was released in February 1993 During 1993 the level of web traffic grew by a factor of 22! The number of web servers in 1993 was around 50, by mid 1994 this had grown to 1500 known public web servers. By 1994 interest was so intensive that the first international conference on the World Wide Web was held Shortly after this, ‘control’ of the web was handed to an independent body of volunteers from key industries – the World Wide Web Consortium (W3C)

7. Early Interactivity The breakthrough came when Marc Andreeson (University of Illinois) later to become Chief Executive of Netscape, wrote a browser called Mosaic in 1993. For the first time there was a method of accessing the Internet without having to learn a complicated command line interface. In 1995, Netscape released a version of their browser called Navigator that had numerous extensions to the HTML language These provided extra ‘mark-up’ facilities and started to introduce security issues – people started to realise the commercial opportunities that the web presented

8. Hypertext The most technically important element, was not the visual aspect, but the use of hypertext and hyperlinks Compare this approach to using books: A novel is read from start to end Reference books are read by following an index or links from one section to another Hypertext works like a reference book, with each WWW page able to link to other pages

9. URLs & Web Search Engines

10. URLs Every page on the Web is hosted on a website which is on a computer connected to the Internet Each of these computers is given a unique address, which is known as a Domain name. The domain name forms part of a URL ‘Uniform Resource Locator’. A complete URL is used to identify the location of a resource on a specific machine (domain name). The URL is often referred to as the web page address

11. URLs continued When searching for information from a particular website on the Internet a user has to take the following steps:  Connect to the Internet either through an ISP (Internet Service Provider), such as Freeserve; or via a local area network at work or college.  Load some web browsing software (e.g. Internet Explorer or Firefox)  Enter the URL (website address) of the resource.  If you don’t know the URL (website address) of a particular company, or you want to search for information on a particular topic, then you can use a Web Search Engine

12. Web Search Engines A Search Engine provides a way to search the contents of millions of web pages ‘at once’ The user locates a Search Engine website, and then enters a key word/words (search string) in the fields provided on the screen The web search engine will then produce a list of URLs of all sites (that it knows of) at which the search string is located This is known as a results list and these can be very very long! If we know how they work, we can make sure our OWN web sites and pages can be found by other people, using typical search techniques

13. Web Search Engines cont’d There are several types of Search Engine The Crawler Engine ‘crawls’ the internet, indexing the contents of pages it finds, following links E.g. Google The Human Engine (or Directory) People identify categories into which a particular site might fit E.g. Yahoo The Portal Pulls together the results from several search engines into a single page E.g. Ask Jeeves

14. Web Search Engines cont’d Crawler engines are the most prolific and arguably the most powerful A crawler based search engine has several essential parts present in all such search engines The crawler, or spider algorithm itself The Indexing algorithm The program to search the indexes

15. Search Engine Optimisation: for the designer This is a skill that is currently in demand SEO specialists make sure that all required “hooks” are in place to get a business’s pages indexed by search engines Page title, appropriate meta tags, ALT text on images Not too much reliance on ‘flashy’ stuff (you cannot index an image! Spiders read text, not animations and scripts Above all, lots of relevant, well written content on the page Employing an experienced copywriter can pay dividends in achieving good search engine placement

16. Using Search Engines Boolean Operators:  AND or +  All the terms joined by must appear in the pages or documents  OR – At least one of the terms joined by must appear in the pages or documents  NOT or –  The term or terms following must not appear in the pages or document.  FOLLOWED BY – One of the terms must be directly followed by the other  NEAR – One of the terms must be within a specified number of words of the other  Quotation Marks – The words between the “quotation marks” are treated as a phrase, and that phrase must be found within the document or file

17. Other SE Functions Google has a “define” service which looks up terms for you Like a good dictionary Type “define:” followed by the term Other Google services are listed here: http://www.google.com/help/features.html Natural-Language Queries: A popular natural language query site is AskJeeves.com. Currently they only work with simple queries; but competition is heavy to develop a natural-language query engine that can accept a query of greater complexity

18. Web Search Engines cont’d We will now look at some examples of different Search Engines, and practise some examples from the handout available on Blackboard titled Search Strategies Exercise.