Technologies for EC/EB Walt Scacchi FEMBA 290 Winter 2003
Copyright (C) 2003, Addision-Wesley Chapter 3 The World Wide Web
Copyright (C) 2003, Addision-Wesley Figure 3.1 Focusing on the top layers.
Copyright (C) 2003, Addision-Wesley The World Wide Web Client/server application Layered on top of Internet Web page – basic information unit Web site – set of related pages Hyperlink – logical page-to-page link Home page – Web site’s starting point
Copyright (C) 2003, Addision-Wesley Web Software Browser Client-side application program Internet Explorer, Netscape/AOL, Mozilla, Opera,... Requests and displays (views of) Web pages Web server Server-side application program Where a Web site resides Manages access to Web site contents Fills page requests – “serves” pages
Copyright (C) 2003, Addision-Wesley Figure 3.2 A Web site consists of a set of related (hyperlinked) Web pages.
Copyright (C) 2003, Addision-Wesley Figure 3.3 The Web enables connections between a Web browser and a Web server.
Copyright (C) 2003, Addision-Wesley Web Servers Server hardware The host computer Server software Application program Web server (Apache, IIS) Database server server Runs on server hardware or host
Copyright (C) 2003, Addision-Wesley Figure 3.5 A URL (Uniform Resource Locator).
Copyright (C) 2003, Addision-Wesley Figure 3.8 A simple web page and its source HTML. HTML is a markup language Understood by all Web browsers Incompati- bilities do exist
Copyright (C) 2003, Addision-Wesley Interactivity Early browsers limited to static pages Business need for Animation, sound, flashing logo Access to global markets Client side data input Need for client side interactivity
Copyright (C) 2003, Addision-Wesley Figure 3.12 A data entry form.
Copyright (C) 2003, Addision-Wesley Client-side Interactivity Scripts Macro-like instructions JavaScript, Jscript, VBScript Embedded in HTML text Applet Small program executed within browser Java, VisualBasic Plug-ins and helper applications
Copyright (C) 2003, Addision-Wesley Figure 3.13 Some popular plug-ins. Plug-in is “integrated” software application Processes registered file types (e.g., proprietary file formats) Often available as free download
Copyright (C) 2003, Addision-Wesley Web Information Systems Client-side interactivity Server-side interactivity Personalized marketing JIT inventory Inter- and intra-corporate communication
Copyright (C) 2003, Addision-Wesley Figure 3.14 Multiple servers can run on the same host. Server is software
Copyright (C) 2003, Addision-Wesley Figure 3.15 Multiple servers can run on multiple interconnected hosts. A Web or Application Server is software!!
Copyright (C) 2003, Addision-Wesley Figure 3.16 Separate firewalls at each layer provides defense in depth. Firewall protects Internal network from public network Runs on Router (via Network Address Translation) Host Server Workstation
Copyright (C) 2003, Addision-Wesley Web Applications Applications that support a Web information system Client/server Browser on client side Server software on server side Middleware translates between HTML Non-Web server format
Copyright (C) 2003, Addision-Wesley Figure 3.17 Middleware connects two (or more) applications/servers. Server-side middleware links Web server Database server Other applications
Copyright (C) 2003, Addision-Wesley Maintaining State The Web is stateless Each transaction is independent No problem for Web surfing Web information system is stateful Series of related transactions Must “remember” previous steps Cookies provide one solution; another is registration, login, and tracking via DB
Copyright (C) 2003, Addision-Wesley Figure 3.18 The shopping cart metaphor. A cookie is the key to maintaining state
Copyright (C) 2003, Addision-Wesley Figure 3.21 A personalized web page. A cookie is the key to personal- ization