Outline. Web browsers & Web servers

Transcription

1 Web browsers & Web servers 1 Outline Goals and Objectives Topics headlines Introduction Finding a web page Browser Tasks Top browsers Browser window structure Internet Explorer Netscape / Mozilla Opera Crazy Browser Managing web pages Browser Cache Plug-ins Bookmarks History list Customization Security Wireless browsing Web servers Summary 2 1

2 Goals and Objectives Goals Understand Web browsers and Web servers Objectives Browser Tasks Browser Window Structure Microsoft Internet Explorer Netscape Communicator / Mozilla Firefox Opera and Crazy Browser Managing browsers: cache, plug-ins, customization Managing surfing: bookmarks, privacy, security Browsers for hand-helds Servers 3 Topics Headlines Introduction need Web browser to view Web pages Finding a web page browser uses URL of web page to locate server Browser Tasks viewing, navigation, file downloading, printing 4 2

3 Most common Browsers Internet Explorer Netscape / Mozilla Firefox Browser Window Structure All have title bar, menu bar, toolbars status bar Internet Explorer Most commonly used, designed for No tabs, filters, skins 5 Netscape / Mozilla / Firefox Opera Claims to be fastest browser Skins Crazy Browser Imitates IE, but tabbed, Popup filters and killers 6 3

4 Managing Web Pages in Browser Each page URL XHTML file(s) Content display Browser Cache Speed up page downloading Plug-ins Enable handling different file types 7 Bookmarks History List trace past navigation experience Customization Change browser colors, fonts, and other settings to suit use and style Security HTTPS, digital keys, and certificates Wireless Browsing Web server introduction 8 4

5 Introduction Browser: client program Request file Display web page content Execute program Output: document User request page type / click on link Browser Locate and retrieve page(s) from server(s) HTTP 9 TABLE 1.2 HTTP Request Methods 10 5

6 TABLE 1.3 First Digits of HTTP Status Codes 11 History Mosaic -- NCSA (Univ. of Illinois), early 1993 First wide-spread GUI-based Led to explosion of Web use Initially for X-Windows, under UNIX, Ported to other platforms by late

7 Accessing a Web-page Type page URL Browser send URL to DNS server Reply: IP address of requested server TCP/IP packets server through routers Web server Receive packets Locate file Send to browser through routers

8 Browser Tasks Viewing Navigating Downloading Printing tools 15 Top Browsers IE Netscape / Mozilla / Firefox 16 8

9 Browser Window Structure 17 Internet Explorer Menus: File Edit View Favorite s Tools Help Toolbars: Standard buttons Address bar (URL) Links toolbar Status bar 18 9

10 Netscape / Mozilla Modules: Navigator Inbox Newsgroups Composer Address book Instant messenger Menus: File Edit View Go Communicator Help Toolbars: Navigation toolbar Address bar (URL) Personal toolbar Status bar 19 Netscape / Mozilla 20 10

11 Netscape / Mozilla 21 Opera Downloaded: When crashes starts where left off Menus: File Edit View Navigation Bookmarks Mail Window Help Toolbars: Main bar Navigation bar Address bar Personal toolbar Page bar Status bar 22 11

12 Opera 23 Crazy Browser Menus: File Edit View Favorites History Groups Options Tools Tabs Help Toolbars: Navigation bar Address bar Links bar Status bar 24 12

13 Managing web pages 3 aspects: URL (X)HTML file Display in browser Save page URL favorite in IE bookmark in Mozilla Print Save / Save As from File menu 25 Browser Cache Speeds up retrieval and display of revisited pages 2 cache types Memory (check 1 st ) During current session Disk (check 2 nd ) From previous session 26 13

14 Plug-ins Programs: launched by browser Separate, but appear to be part of browser Informs user when plug-in needed E.g., Adobe Acrobat Reader: view.pdf files Macromedia Shockwave: play animation and sound Macromedia Flash: to view animations Apple Quicktime: play text, animations, video, and sound 27 Bookmarks Saved link to page Can name bookmarked links Cannot view on another browser/machine Bookmark managing task: Add Delete Organize IE: Favorites 28 14

15 History List Retrace surfing steps Can be: Short term Memory cache Long term Disk cache CRTL + H: usually displays history list Some browsers also have separate History button 29 Customization Can customize: Default options Default ( home ) web page Fonts Colors Toolbars Image Display Java and Javascript Style sheets Cookies options Configure mail and news groups server Change cache size 30 15

16 Security Prevent unauthorized access to info passed between clients and servers Via encryption and decryption Secure Sockets Layer (SSL) developed by Netscape HTTPS protocol Encryption systems incorporate: Public and Private Key Digital Certificate 31 Handheld / Wireless Browsing Hand-held PDAs Cell phones Sync: download pages for later viewing Diffs: screen size / disk space / special browsers 32 16

17 33 Browser Summary Access to web page Enable users tasks IE / Mozilla / Firefox Generic structure Menus and Toolbars to Change settings Perform browser tasks Cache speed up display of re-visited web pages Plug-ins support Customized to suit user style Security Handheld / Wireless browsing 34 17

18 Web servers Respond to browser requests document existing dynamically built Browser-server connection Multiple request-response cycles All Browser-server communications use HTTP: Hypertext Transfer Protocol 35 Web servers run as background processes in OS Monitor communications port on host Accept HTTP messages when appear 36 18

19 All current Web servers came from either original (CERN) second one (NCSA) 37 Web servers have two main directories: Server root (server system software) Document root (servable documents) accessed indirectly by clients actual location set by server config Virtual document trees Virtual hosts 38 19

20 Proxy servers Web servers now support other Internet protocols Apache (open source, fast, reliable, most common) Op control: Directives ServerName ServerRoot ServerAdmin, DocumentRoot Alias Redirect DirectoryIndex UserDir IIS Op control: GUI interface 39 Servers Summary Running as daemon Respond to requests Delivery documents Apache most common IIS follows 40 20