Скачать презентацию Advantages to a single-page site n n All
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Advantages to a single-page site n n All the information can be viewed quickly The full web site can be printed with just one print command Links within different parts of the document is quick Easy to save it on the hard disk for future use
Advantages to a single-page site n n Give an introduction to the page and say who will benefit from the page Give a good table of contents so that the reader can go directly to the page he/she is interested Always have a link back to the main page or the table of contents page Since the table of contents cover all the related pages the reader can only bookmark the main page
When one page is enough
Organizing a simple site n n n Organize the site with short, quick-read pages with graphical icons A good Web page will make the organization visible on the Internet All Web pages should have the postal address, contact details and email address Always make the Web pages identical Try to avoid standard clip art graphics and other most popular graphics (Don’t copy too much!!)
Organizing a simple site
Organizing a larger site n n Very similar to a simple site. Make sure you write a paragraph explaining the contents of the site and the intended audience Always organize the main links on your site according to the questions or desires of your readers If you want you can put the contact details on all the major pages of your site Providing topic specific link pages is a very good way to organize a large Web site
n n n Try to keep the number of choices (list or icons) on any index to a maximum of 7 If you need to present more than 7 links try to break the list into groups Avoid putting any page more than two links away from the home page Always add comments to your Web page code. Enclose your comments between tags To include comments in Java. Script put the // at the beginning of each comment that is a single line
n n For Java. Script comments more than one line start the comment with /* and end them with */ In style sheets, start comments with /* and end with */ You should have or tag The above will hide the script from the older browsers that would otherwise treat it as regular text and display it on the page
Publicizing n n n Somebody tells them about your site address People may follow a link from your site to someone else’s site Your site can be listed in a search engine such as Yahoo or Google Add the site address to your business card or company literature A spider is an automated computer program that spends all day looking at Web pages all over the Internet and building database of the contents of all the pages it visits
Listing your pages n n n A search engine (portals) is an automated computer program that looks in a database index for pages containing specific words or phrases To publish it on the major search engines you must fill in the forms they provide with, brief description, category, list of key words etc. . URL stands for Uniform Resource Locator, which is the technical name for the address of a Web page
Criteria used by search engines to match to a specific search n n n Do the key words appear in the
Loading another page automatically n n If you move your page to another directory say some thing like “ This page has moved to …. ” with the new address (and link it) You can make any other page load automatically after a specified amount of time e. g
Documenting the full address of a page It is not a good practice to use just the filename links e. g: n It is a good practice to use the full URL in all links n Always use the full address of the home page in all the link pages n Use the
Planning for the future of HTML The best sources of HTML standards are: http: //www. w 3. org and http: //www. htmlcompendium. org n Check the http: //www. microsoft. com or http: //home. netscape. com for latest versions of the browser software
HTML beyond the Web n n Use style sheets and scripting languages to create more advanced pages Integrate interactive media, and databases with the HTML code wherever needed Use the new data security standards to carry out financial and other sensitive transactions Today all versions of the Microsoft Windows operating system uses HTML as a fundamental part of the user interface
From calculators to communicators n n n Today computer is not a number crunching device. It is rather a communication device Today you share information using the networked computers Computers are used for chat, email, interactive video, music etc…. .
HTML as an User Interface n n n In conjunction with HTML-enabled software such as Microsoft Office 2000, HTML is the common standard interface for word processing, spreadsheets, and databases Netscape communicator as the name indicates uses HTML to integrate all types of media into email, discussion groups, schedule management, business documents and collaborate project management This HTML standardization will help us to publish in a standard way so that it will look the same to anyone in the world
The digital media revolution n To deliver television quality video the technology is there but the cost still is very high!! Today the same box under your TV can also be used for Internet access (Interactive transmission) Since HTML is the glue that links all the multimedia it is certain HTML will dominate the digital communications industry
XML: Unity in diversity n n n HTML has been the foundation for the e. Xtensible Markup Language (XML). XML provides a truly universal format for exchanging all types of information over the Web XML is a bridge between XML and SGML ( Standard General Markup Language)
What are protocols? n n n Protocol is the special set of rules that end points in a telecommunication connection use when they communicate Both end points must recognize and observe a protocol. Protocols are often described in an industry or international standard. Transmission Control Protocol (TCP), which uses a set of rules to exchange messages with other Internet points at the information packet level Internet Protocol (IP), which uses a set of rules to send and receive messages at the Internet address level Additional protocols that are usually packaged with a TCP/IP suite, including the Hypertext Transfer Protocol (HTTP) and File Transfer Protocol (FTP), each with defined sets of rules to use with corresponding programs elsewhere on the Internet
How e-mail works on the Internet n n The Simple Mail Transport Protocol (SMTP) specifies how electronic messages are exchanged between computers using the Transmission Control Protocol or TCP provides a reliable exchange of data on the Internet without any possibility for loss of data SMTP is used to exchange messages between servers or between a client and a server SMTP is used to deliver the messages and an e-mail client program is used to retrieve the messages
SMTP E-mail uses the client-server method to allow mail to be exchanged n Client exchange messages with a server that is ultimately responsible for delivering the e-mail messages to the destination n On the server computer each user is assigned a specific mailbox. Each mailbox has a unique address e. g mailbox@computer mailbox name and the computer name n The mailbox part is normally made from a user’s name. The hostname is chosen by a network administrator n
E-mail n n The last few alphabets represent the domain name categories The main categories are. com – A company or commercial organization. edu - An education institution. gov - A government organization. mil - A military organization. net - Network service provider. org - Other organizations country code – A country code e. g. . uk, . au, . us
Format of e-mail messages To – The mail recipient’s e-mail address From – The sender’s e-mail address Cc – List of carbon copy addresses Bcc – List of blind carbon copy addresses Date – The date when the message was sent Subject – The subject of the message Reply- to – The address to which a reply should be sent
E-mail client software n n n One of the most popular client software e-mail programs is Microsoft Outlook Express Today Microsoft is installed as part of the Windows operating system In order to use the Outlook program, it must be configured properly Configuration consists of providing user information such as the user name, organization, e-mail address, and reply address It is also important to identify the server computer to which the client will connect to send and receive mails
There is a server associated with the incoming and outgoing messages n The incoming mail uses POP 3, the Post Office Protocol, whereas the outgoing mail server uses SMTP n You can change the default settings of the client software e. g you can change the server timeout value, or leave a copy of the mail on the server computer n
Sending an e-mail message n n n Consider an example in which david_ beckham@fcuk. com. creates the e-mail message. David uses the e-mail client to send a message to clinton@aol. com. The message is sent by David to the e-mail server “fcuk. com”. The mail server at fcuk. com will forward the message to the email server at aol. com, where Bill can read that message Remember SMTP is used to transfer messages everywhere except for the client connection at the destination, which uses POP 3
E-mail error messages n n Two of the most common errors stem from the user specifying either the mailbox name or the computer name incorrectly Other specific problems will have their own specific message, which can help to solve the problem
Access to e-mail using the Web Some e-mail servers allow access to the mail system using a World Wide Web browser n The browser acts the same as an e-mail client that allows a user to send and receive e-mail messages n A username and password are required in order to access any mail files e. g Outlook Web Access, Yahoo Web mail etc. . n
Multipurpose internet mail extensions (MIME) n n MIME provide a way for binary programs, graphical images, or other types of files to be attached to an email message MIME standard provides several important features such as - Specifications for other character sets - Definitions for content types such as applications, images, and other multimedia file types - An extended set of possible headers - A method to include several different objects within a single message
Common MIME data type. au – Audio file. bin – Binary file. exe – Binary executable application file. gif – GIF image file. java – Java text source file. jpg – JPEG image file. mid – MIDI audio file. mov – Quick. Time movie file. mpg – MPEG video file. ra - Real audio file. zip - ZIP file
Internet Message Access Protocol (IMAP) n n n IMAP is a newer protocol designed to provide access to electronic messages that are stored on a mail server Unlike POP Internet Message Access Protocol provides direct access to the messages that are stored on the server This allows for mail messages to be managed from any computer at any time IMAP is fully compatible with the MIME and Internet standards IMAP includes concurrent access to shared
FTP clients and servers n n The capability to copy a file between computers is provided by the File Transfer Protocol, or FTP uses connection-oriented TCP as the underlying transport protocol providing guaranteed reliability The primary function of FTP is defined as transferring files efficiently and reliably among host computers and allowing the convenient use of remote file storage capabilities Essentially FTP is a client-server application that uses two ports on both the client and the server
FTP n n In FTP transfer one port is used to exchange FTP control or command information and the other port is used to transfer the data On the FTP server computer, port 20 is used for data transfer and port 21 is used for control by default FTP client can use any port numbers greater than 1023 (Port numbers less than this are reserved for server applications) FTP uses the Telnet protocol on the control connection
FTP Commands n n n An FTP exchange of information consists of requests sent by the client and responses sent by the server After the client connects, the server sends a response to the client either accepting or rejecting the connection This initial response is called greeting If the server accepts the connection, the client sends requests to the server for processing The server sends more responses back to the client. The last request from the server indicates whether the request was accepted or rejected
FTP Commands delete – delete remote file ls – List contents of remote directory put – Send one file ascii – Set ASCII transfer type quit – Terminate FTP session get – Receive file mget – get multiple files mkdir- Make directory on the remote machine binary – Set binary transfer type
FTP Clients n n n FTP client is provided for almost every type of hardware and operating system platform available On a Windows computer an FTP client is installed when the TCP/IP protocol is installed There are two types of access to a FTP server: anonymous FTP and not anonymous Anonymous mode of operation allows public access to files stored on an FTP server (e. g. a manufacture may provide free updates to device drivers or an easy method to distribute shareware applications The non anonymous mode requires an account and password
Free FTP WS_FTP LE is available free for non business users at: www. ipswitch. com n WS_FTP is written as a Windows application rather than a DOS application allowing us to use the mouse rather than the keyboard n Each session will prompt on the screen for the host name and a user ID and password n The left side of the window displays the contents of the local system and the right side of the window displays the contents of the remote system n
n n On the local system, the wsftp 32 directory contents are displayed and the root directory “/” is displayed on the remote system You can perform the following operations by selecting the appropriate button on the display: - Change to a different directory - Make a new directory - Remove a directory - Refresh the current display - Obtain directory information
n n n Between the windows two arrows are used to indicate the direction of the transfer Notice three selections at the bottom of the window The “Auto” selection determines the file type by using the files extension. E. g an. exe file will be set to binary and a file with. txt extension would automatically be set to ACSII
WS_FTP LE n n Below the file transfer type fields. A status window is displayed that contains a complete list of text messages exchanged by the client and server The bottom of the screen provides the options for - Close the current session - Cancel an operation - Open the message log window - Obtain online help - Change the program options - Review the About program info
FTP Servers n n n FTP servers operate on server class computers using operating systems such as Windows NT, Unix, and many others A minimum implementation is required for all FTP servers so that each server regardless of the underlying platform, can be used to reliably exchange information There minimum requirements are specified in RFC 959.
n n An FTP server is responsible for allowing access to the server and mechanisms are provided to authenticate users, access the server file structure, and set file transfer parameters A user is permitted to transfer files only after entering a correct account name and associated password
Telnet Clients and Servers n n The provision of remote terminal access was the very first service implemented to allow user with an interactive terminal session attached to one mainframe computer to remotely connect to another mainframe as though it were directly connected The Telnet protocol (RFC 854) provides for a bidirectional, byte-oriented service using TCP as the transport to reliably deliver messages
Telnet Clients n n n A telnet client is provided when the TCP/IP protocol suite is installed You can run the Telnet client from the Run option on the Start menu To begin a Telnet session, it is necessary to specify the Telnet program followed by the host to connect to Before any interactive commands can be entered the user need to enter a user name and password to gain access to the remote system When a Telnet session is complete it is necessary to disconnect it. This option is available on the Connect pull-down menu. A session is automatically disconnected if the client program is terminated
Telnet Servers n n Telnet servers are available for most hardware and operating system platforms On a Windows computer, it is necessary to locate a third party Telnet server because Microsoft does not provide a Telnet server program By default Telnet server is installed on port number 23 You are encouraged to search the Web for Telnet server applications that can be run on a Windows platform
Troubleshooting Techniques n n Many of the problems experienced when using the FTP stem from the differences between the text and binary files that a user wants to transfer By default, an FTP client will transfer a file using the ASCII mode Hence any other type of file such as an executable or a ZIP file will be modified during the transfer and corrupted Use of WS_FTP makes using FTP program easier