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Comp 2513 E-Commerce Infrastructure 1. Daniel L. Silver, Ph.D. Objectives. To describe the major architectural components of the Internet that form the infrastructure for E-Commerce To discuss HTML – HyperText Markup Language – the language of E-Commerce
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Comp 2513E-Commerce Infrastructure 1 Daniel L. Silver, Ph.D.
Objectives • To describe the major architectural components of the Internet that form the infrastructure for E-Commerce • To discuss HTML – HyperText Markup Language – the language of E-Commerce • References: Chapters 1 and 2 of Sharma Daniel L. Silver
Outline • Following the business evolution on the web • The major architectural components of the Internet • Intro to HTML Daniel L. Silver
Business Evolution on the Web Processes Functionality Web-enabled applicatons Transactions Interactivity Dynamic web pages Publishing Static web pages Time or Maturity Daniel L. Silver
What is an internet? • Communication between two or more potentially heterogeneous networks (LANs) • The “Internet” is a set of standards for inter-network communications Daniel L. Silver
The Client-Server Model • Client – a machine that makes Internet requests for resources (printing, data, processing) • Server – a machine that performs tasks for clients on request and manages network resources • Communications protocol – a set of rules for two or more entities to converse Comm. Protocol Server Client Daniel L. Silver
TCP/IP Protocol Architecture Transmission Control Protocol Internet Protocol Daniel L. Silver
TCP/IP Protocol Architecture • Internet Protocol (IP) – like a postcard that contains: • Destination address (131.162.201.7) • Return address • Block of data (content) • Transmission Control Protocol (TCP) • Ensures the post card gets through • Ensures the order of deliver • Handles errors and control flow Daniel L. Silver
Traditional Client-Server Applications that use the Internet Telnet Protocol Telnet Window Telnet Server FTP FTP Server FTP Client SMTP/POP eMail Client eMail Server TCP TCP IP IP Internet Network Network Physical Physical Daniel L. Silver
Data Encapsulation under TCP/IP Daniel L. Silver
What is the Web? • A class of applications that use the Internet plus a lot of new technologies and standards that facilitate access to resources managed by servers connected to the Internet: • Hardware: Servers • Software: Browsers, Servers • Protocols: HTTP, HTML, MIME Daniel L. Silver
Major Architectural Components of the Web Client 1 Browser HTTP TCP/IP Server A HTTP Server App. Server Database Server Internet Client 2 Browser index.html URL Server B Server C Daniel L. Silver
Components of the Web • Website - a collection of files and associated software on a server (may run on client or server) • Web Server – a software system that can field requests for website files (HTTP server) and applications (Application Server) • Web Browser – a GUI client application (Netscape Navigator, Internet Explorer) that facilitates access to Website files and software for display of data, video and audio • Database Server – provides an interface to a structure database for web applications Daniel L. Silver
Components of the Web • HTTP - HyperText Transfer Protocol • URL - Universal Resource Locator for a file on the internet (www.acadiau.ca) • Webpage – a representation of information understood by the browser • HTML - HyperText Markup Language WC3 definitions For a more user friendly resource: http://www.pierobon.org/iis/index.htm Daniel L. Silver
HTTPHyperText Transfer Protocol • The application protocol of the Web • Like FTP it is layered on top of TCP/IP HTTP Web Browser HTTP Server TCP TCP IP IP Internet Network Network Physical Physical Daniel L. Silver
HTTPHyperText Transfer Protocol Client There is a 3 step process per transaction: Browser accepts request from keyboard … • (a) Client locates & sends an HTTP request for a webpage (b) Client sends optional header info to server about client (browser configuration, acceptable files) (c) Client may send addition data (used by POST method) • (a) Server responds with a status line (eg. HTTP/1.1 200 OK) (b) Server sends header info to client about itself and requested file (server config., file format) (c) Server sends the requested data or optionally additional error information • If HTTP 1.0, by default server breaks the connection If HTTP 1.1, server can let client break connection … Browser loads, interprets and displays page. For further info on HTTP see http://www.w3.org/Protocols/rfc2616/rfc2616.html Internet Server Daniel L. Silver
How is the Webpage Located? • URL – Universal Resource Locator • The address of an resource on the Internet • http://www.acadiau.ca or http://eagle.acadiau.ca • ftp://a.cs.uiuc.edu/ • file://C:/Work/Acadia/1503.w01/index.html • <protocol>://<machine>:<port>/<file> • Default port = 80 • Default file = index.html • Machine = IP address. How does it get this? Daniel L. Silver
What does an HTTP Request/Response look like? • HTTP request headers: • Request: GET, POST, PUT, DELETE, etc • Header - plain text • Info about the object (MIME etc) • Methods that can be processed by client • Example of a Request Header: GET /danstech/sample.html HTTP 1.0 Accept: text/plain Accept: text/html User-Agent: Mozilla/2.0 <CR/LF> Daniel L. Silver
HTTP Request/Response Example you can try … > telnet eagle.acadiau.ca 8080 Trying 131.162.201.7... Connected to eagle.acadiau.ca. Escape character is '^]'. GET /danstech/index.jsp HTTP/1.0 HTTP/1.1 200 OK Content-Type: text/html Connection: close Date: Thu, 19 Sep 2002 12:40:54 GMT Server: Apache Tomcat/4.0.4 (HTTP/1.1 Connector) Set-Cookie: JSESSIONID=ECECB564E60E795E0B2E86D330D76649;Path=/danstech <html> <head> <title>Danny's Car Shop</title> … </html>Connection closed by foreign host. Daniel L. Silver
MIME • HTTP uses a predefined set of document formats borrowed from eMail (actually, HTTP was modeled after an eMail protocol) • MIME - Multipurpose Internet Mail Extensions • Defines the content format • Content-type: <data type>/<subtype> • text/html • text/plain • image/gif • video/mpeg • application/msword Daniel L. Silver
A Web session is Connectionless • TCP/IP is connection-oriented • But each HTTP request/response makes a new connection • Potentially, each browser/server operation is unaware of any related connections • Why do this? A sense of state is needed for E-Commerce transaction processing • We’ll discuss this further next day! Daniel L. Silver
HTML • HyperText Markup Language • language used to represent webpages • Markers call “tags” are used to specify how elements of page should be displayed • <centre>Hello World!</centre> • Fixed vocabulary of tags • Describes the structure of a document not its specific layout (layout may change size of window and size of font) Daniel L. Silver
HTML • HTML files end with either .html or .htm • Can be created by • A text editor (Wordpad, Notepad, vi) • A Webpage editor (Netscape Composer) • A translation from another document format (MS Word to HTML) Daniel L. Silver
A Basic HTML Document <HTML> <HEAD><TITLE>First Page</TITLE></HEAD> <BODY BGCOLOR= '#0000ff'> <!-- <BODY BGCOLOR= '#ff0000'> --> <FONT FACE="Arial, Helvetica" COLOR='#FFFFFF'> <CENTER> I'm quite hyper - even the language I speak is Hyper-Text-Markup-Language <B> - Vivek</B> </CENTER> </FONT> </BODY> </HTML> Daniel L. Silver
Basic Syntax of HTML • Comments • Background Color • Text Formatting • Lists • Images • Links to other documents • Tables • Frames Daniel L. Silver
HTML - Comments General: <!-- comment -- > Examples: <!-- This is a comment -- > <!-- <title>My First Page</title> -- > Daniel L. Silver
HTML - Colours By Color Name • black, red, white, yellow, olive, tan, blue, navy, green, magenta, brown, turquoise By Pigment Mix <BODY BGCOLOR= '#0000ff'> • #rrggbb • rr, is the amount of red in the colour (00 is none and FF is a lot) • gg is the amount of green • bb is the amount of blue • <BODY BGCOLOR= '#00ff00'> is very green • <BODY BGCOLOR= '#880088'> is purple Daniel L. Silver
HTML- Text Formatting • bold<b> bold </b> • italics<i> italics </i> • underlined<u> underlined </u> • typewriter<tt> typewriter </tt> . • <font size=n> and </font>This is going to be <font size = +3>BIG</font> • <font color=red size = -1>Combining color and size</font> Daniel L. Silver
HTML - Fonts Types Verdana<font size=+2 face="Verdana">Verdana</font> Arial <font size=+2 face="Arial">Arial</font> Helvetica<font size=+2 face="Helvetica">Helvetica</font> Impact<font size=+2 face="Impact">Impact</font> Comic Sans MS<font size=+2 face="Comic Sans MS">Comic SansMS</font> Daniel L. Silver
HTML- Text Positioning • Paragraph: <p> and </p><p>This is a new paragraph.</p> • Line break: <br> We would prefer the following: <br> • Centering: <center> and </center> <center><b>I am boldly centered</b></center> • Verbatim: <pre> and </pre> <pre> This will appear exactly as seen here without any …… ….. Changes </pre> Daniel L. Silver
HTML - Headings <HTML> <HEAD><TITLE>Size Tags</TITLE></HEAD> <BODY> <FONT FACE="Arial, Helvetica"> <H1> This is size H1 </H1><BR> <H2> This is size H2 </H2><BR> <H3> This is size H3 </H3><BR> <H4> This is size H4 </H4><BR> </FONT> </BODY> </HTML> Daniel L. Silver
HTML – Lists Example: <HTML><HEAD></HEAD> <BODY> Apples <UL> <LI>Red <LI>Green </UL> Mangoes <UL type=square> <LI>Green <LI>Yellow </UL> </BODY> </HTML> Ordered Lists: <OL> Unordered List: <UL> Daniel L. Silver
HTML - Images • Various digital image formats can be embedded with in HTML: .gif, .jpg • Example • See www.bellsnwhistles.com as source of images and other objects. <BODY> <H1>My new baby girl.</H1> <IMG SRC=“NicoleSilver.jpg”> </BODY> Daniel L. Silver
HTML – Links Display in current browser window: <HTML><HEAD></HEAD> <BODY> <A HREF='First.html'>Link to First.html</A> </BODY> </HTML> Display in a new browser window: <HTML><HEAD></HEAD> <BODY> <A HREF=‘First.html’ target=‘anotherFrame’> Link to First.html</A> </BODY> </HTML> Daniel L. Silver
HTML- Tables <HTML> <HEAD></HEAD> <BODY> <TABLE BORDER='2'> <TH>Column 1</TH><TH>Column 2</TH> <TR> <TD>Cell 1</TD><TD>Cell 2</TD> </TR> <TR> <TD>Cell 3</TD><TD>Cell 4</TD> </TR> </TABLE> </BODY> </HTML> Daniel L. Silver
Resources • HTML Guides: www.cwru.edu/help/Help_www2.htmlhttp://www.cc.ukans.edu/~acs/docs/other/HTML_quick.shtml • A great interactive tutorial.http://www.davesite.com/webstation/html/ • Other how-to guideshttp://htmlgoodies.earthweb.com/http://look.html.tucows.com/ • PowerHTML is a freeware editor for HTML: http://library.thinkquest.org/16728/msie/powerhtml.html • Fun: Europe vs. Italy (Flash technology)http://www.infonegocio.com/xeron/bruno/italy.html Daniel L. Silver