1. 1 PROJECT Web-based Database Applications Lecture 1: Basic Internet Concepts & Databases - the History

2. © H. Afsarmansesh, 2003 2 From “local” database applications to “web-based” or web-enabled applications  Characteristics  Requirements  Advantages / disadvantages  Approaches, mechanisms, and tools  …

3. © H. Afsarmansesh, 2003 3 Remote database access  What if you are in an airport and need to access the information stored on your DB?  Characteristics (limitations) of the traditional “local” database applications  What is needed to make it happen?  Geographical location independence  User interface  Access rights and security

4. © H. Afsarmansesh, 2003 4 History of Hypertext & Hypermedia - 1 Centralized Sequential text handling:  In 60s – Simple text  Print, store, edit, visualize  In 70s – Text processors (programs, text, etc.)  Interpreters  Reserved symbols, and characters  E.g. Vi, emacs

5. © H. Afsarmansesh, 2003 5 History of Hypertext & Hypermedia - 2 Sequential text handling:  Late 70s / early 80s – word processors (documents)  Centralized, User friendly  Interpreting symbols and commands  Troff, Nroff, Latex  Late 70s / early 80s – Internet  Network of computers around the world  Email  File transfer (ftp)  Telnet (login to remote computers)

6. © H. Afsarmansesh, 2003 6 History of Hypertext & Hypermedia - 3 Linking document blocks:  Mid 80s –Hypertext / Hyperlinks  Breaking the sequentiality  Interpreting symbols & commands + file names  Centralized  Hypercard on Mac.  Hyperlinks - file names (addresses) introducing links  Mid 80s – (S)GML (Generalized Mark-up Lang.)  Mark up language to describe Documents for formatting and printing

7. © H. Afsarmansesh, 2003 7 History of Hypertext & Hypermedia - 4 Linking document blocks:  Early 90s –Hypermedia  Hypertext + multi-media (audio, visual, …)  Early 90s – WWW  Generalization of hypermedia + internet  documents located at different network nodes  Hyperlinks also include the address of the machines  2 physicists at CERN used hyperlinks over the internet, to exchange documents  Mid 90s – A graphical interface to fetch Docs from the WWW

8. © H. Afsarmansesh, 2003 8 History of Hypertext & Hypermedia - 5 Linking document blocks:  Mid 90s –Static HTML page  Special case of hypermedia / hyperlinks developed for WWW  Other languages also exist  Encyclopedia CD-ROMs’ mark ups are not HTML  The interpreter of the HTML (for www) is called a browser  A set of opening / closing tags format different parts of the HTML page

9. © H. Afsarmansesh, 2003 9 History of Hypertext & Hypermedia - 6 Towards Dynamic HTML pages:  late 90s / early 2000 – Dynamic HTML page  Applets (small applications)- code included within the HTML page (e.g. for animation, calculation of C to F)  Servlets - code written in JAVA-like language, exists outside the HTML page, referenced by the URL, requires a web server to run  CGIs - similar to Servlet, but written in any language

10. © H. Afsarmansesh, 2003 10 History of Hypertext & Hypermedia - 7 Internet Browsers:  In 90s – Browsers (e.g. Netscape and Explorer)  Paging the long HTML files  Support the interpretation of actions (in static & dynamic HTML pages) within the document  Preserve the security of the host machine:  For static actions (applets), make sure that the actions do not violate the host machine’s protection and security

11. © H. Afsarmansesh, 2003 11 History of Hypertext & Hypermedia - 8 Internet Browsers:  Browsers handling the execution of actions  Interpretation of actions within the HTML document:  local actions (static HTML page) u Read the time / date from the local machine u Animation u Exchange the format for temperature (from C to F)  Remote actions - accessing the server (dynamic HTML page) u Read / fetch information from the database u Calculate the exchange rate for currency (for today)

12. © H. Afsarmansesh, 2003 12 History of Hypertext & Hypermedia - 9 HTML page editors: HTML pages can be generated by:  Text editors (e.g. WORD, using the HTML manuals as the base)  Creating the formatted page in WORD, then using the converter from the WORD page to the HTML page [ save-as WEB page, then view the Source]  Use the tools to compose formatted web pages as a multi-media object [ file, edit, MS word to automatically generate web page]  Fancy HTML page composers (e.g. the Front page)