Downloading and Storing Data

New Perspectives on The Internet, Fifth Edition—Comprehensive, 2005 Update Tutorial 6

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XP

Downloading and Storing Data

Using FTP and Other Services to

Transfer and Store Data

Tutorial 6


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XPObjectives

• Learn what FTP is and how it works.

• Explore how to use an FTP client program and Web browser to transfer files.

• Navigate an FTP site using a Web browser.

• Learn how to compress and decompress files and to check them for viruses.


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XPObjectives

• Download an FTP client program using a Web browser.

• Download a compression program using an FTP client program.

• Install and use a compression program.

• Trace the connection between your computer and a remote computer.


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XPObjectives

• Explore storage options on the Internet.

• Learn about emerging technologies for collaborative authoring on the Web.


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XPUnderstandingFile Transfer Protocol

• FTP, or File Transfer Protocol, is the Internet protocol that transfers files between computers that are connected to the Internet.

• The site to which you are sending files and from which you are receiving files is called an FTP site, FTP server, or a remote computer.

• When you use your computer to connect to an FTP site, it is called the local computer.


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XPUnderstandingFile Transfer Protocol

• When you send a file using FTP, you upload the file to send it from your computer to the FTP site.

• When you receive a file, you download the file from the FTP site and receive it on your computer.

• You connect to a remote computer and request it to either receive files from your computer or transfer files to your computer.

• FTP seamlessly transfers files between different operating systems.


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XPFile Transfer Modes

• You can select one of two file transfer modes—ASCII or binary—that you want to use before transferring the file.

• ASCII text contains symbols typed from the keyboard but does not include any nonprintable, binary codes.

• Many files such as pictures, movies, sound files, and graphics are binary.

• Choose ASCII mode to transfer plain-text files.

• Choose binary mode for transferring everything else.


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XPFile Types and Extensions

• The decision to transfer a file using binary or ASCII mode is largely determined by noting the file’s type. The file type can be determined by its extension.

• A file extension is the last three characters following the period in the filename.

• You can download files with a file extension of .txt in ASCII mode.

• You should download files with other file extensions (.doc, .xls, etc.) in binary mode.


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XPFile Types and Extensions

Filename & Extension Extension

TransferMode Type of file

picture.bmp .bmp Binary Microsoft Paint

readme.doc .doc Binary Word document

spinner.exe .exe Binary Executable program

starship.gif .gif Binary Picture

index.html or index.htm

.html or .htm

ASCII HTML document (Web Page)

chapter1.zip .zip Binary Compressed file

readme.txt .txt ASCII Text file


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XPConnecting to an FTP Server

• To transfer files between your computer and a remote computer, you must first connect to the remote computer.

• You can connect to a remote computer by logging on to it using an FTP client program or your Web browser.

• Some FTP client programs and browsers will select the file transfer mode of binary or ASCII automatically.


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XPFTP Using an FTPClient Program

• An FTP client program resides on your PC and transfers files between your computer and an FTP site.

• Most FTP client programs have menu bars or toolbars to help you execute commands.

• FTP client programs transfer files quickly and provide features that let you resume downloading a file when your connection is lost or interrupted.


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• When selecting an FTP client program, choose one that supports all or most of the following desirable features: Multipane display showing both the local & remote

computer directories. Allows you to transfer multiple files in one FTP

session. Permits drag and drop file transfers. Simplifies the process of deleting directories on

local and remote computers.


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• Desirable features (continued): Allows you to transfer selected files unattended. Recovers interrupted file transfers by continuing

the transfer process from the point of interruption. Reconnects automatically to sites that disconnect

a transfer when your connection exceeds the maximum allotted time.


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XPFTP Using a Web Browser

• Most Web browsers, including Microsoft Internet Explorer and Netscape Navigator, support FTP, but have limited functionality when compared to FTP client programs.

• To upload a file, you must drag it from your desktop or Windows Explorer and drop it in the correct location in the browser window.

• To download a file, you select the file to download and tell the browser where to save it on your computer.


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XPFTP Using a Web Browser


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XPLevels of Access for FTP Servers

• To use a remote computer, you must identify yourself, or log on, by supplying your user name and password.

• Public access: anyone can connect to the FTP site. Access is restricted to only those files and folders designated for access by public users.

• Restricted access: do not allow public visitors.


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XPAnonymous FTP

• Anonymous login: logging on to one of the many publicly accessible, remote computers connected to the Internet.

• You use anonymous as your user name.

• Anonymous FTP session: when you download or upload files using an anonymous login.


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XPAnonymous FTP


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XPAnonymous FTP

• Public FTP sites usually impose limits on uploading files or provide only one publicly accessible directory to which you can upload files.

• Access to selected files and directories is also limited.

• You should obey all rules and regulations regarding anonymous access.

• Look for the site’s acceptable use rules and policies in the readme.txt file in the pub (public) directory.


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XPFull-Privilege FTP

• Full-privilege FTP: an FTP site that is not public and requires a user name and password to access its content.

• The system might automatically direct you to a particular directory on the FTP site in which you have been given rights to upload and download files.

• You can usually store files for longer periods than you can on a public FTP site.


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XPUsing a Public Directory

• Public directory (pub): the directory that some public FTP sites allow users with anonymous FTP access to view.

• Webmaster: the title given to the manager of a website.

• The webmaster must monitor the files uploaded to a public directory on a regular basis to check for viruses and to find and delete any illegally uploaded files.


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XPUsing a Web Browserto Navigate an FTP Site

• FTP sites are organized hierarchically, much like the folders and files on a computer’s hard drive.

• When you access an FTP site, you usually enter at the site’s root directory.

• Most sites prevent users with anonymous logins from accessing some files and directories in the root directory.


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• An FTP site usually stores directories (folders) and files.

• Double-clicking a file either opens the file in a new browser window or in a program window so you can view the file, or it begins downloading the file to your computer.

• Double-clicking a folder opens the folder and displays its contents.


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XPChecking Files for Viruses

• Computer viruses pose a real and potentially costly threat to anyone using the Internet.

• Computer viruses are programs that “infect” your computer and cause harm to your disk or programs.

• You must know how to detect and eradicate viruses if you plan to download anything, including data, programs, or e-mail attachments.


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• Virus detection software, also called antivirus software, regularly scans the files on your computer and files being downloaded to your computer.

• Files are compared to a signature that known viruses carry.

• A virus signature (also called a virus pattern or a virus definition) is a sequence (string) of characters that is always present in a particular virus.

• When the virus detection program finds a virus signature, it warns you. You can either delete the file or ask the virus detection program to remove the virus.


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• Two popular choices for protecting PCs are Norton AntiVirus and McAfee VirusScan.

• Antivirus software must be turned on, properly configured, and include current virus patterns to protect your computer from viruses.

• You must regularly download virus patterns from the server to keep your computer safe.

• One of the best ways to protect your computer from viruses is to be careful about which files you download and the sources you use to get those files.


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XPVisiting and Using aDownload Site

• A good way of locating software on the Internet is to use one or more Internet search engines.

• Several Web sites provide links to freeware and shareware programs. Some of these same sites also allow you to download programs directly.


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XPDownloading Programs

• Freeware: software that is available to users at no cost and with no restrictions.

• Users must accept the implicit or explicit warning that the software might contain bugs.

• Bugs: errors sometimes contained in freeware due to limited testing of the software.

• A lot of good-quality commercial software started as freeware.


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• Shareware: similar to freeware, but it is usually available for free during a short evaluation period.

• After the evaluation expires, shareware stops functioning.

• Users are expected to stop using the shareware after the specified initial trial period and uninstall it from their computers.

• Anyone who likes the program and wants to continue using it can purchase a license.

• Shareware is usually more reliable than freeware because the shareware developer is sometimes willing to accept responsibility for the program’s operation.


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• There are three popular ways to turn shareware users into paying customers:

Build a counter into the program

Insert an internal date checker

Use a “nag” screen that appears each time you start the program


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Limited Edition (LE) or Evaluation Version: a restricted version of a shareware program.

Provides most of the functionality of the full version that is for sale.

Omits one or more useful features of the full version.

You can sometimes download a limited edition version and use it for free.


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XPUsing a Web Browser to Download an FTP Client Program

• The time it takes to transfer the program files varies based on the speed of your Internet connection and the amount of traffic at the FTP site.

• If you encounter problems while downloading a file, stop the process by clicking the Cancel button and try again later.

• After downloading anything from the Internet, your first priority is to scan the file for viruses.

• After installing any program, you can delete the downloaded files from the drive and folder to which you downloaded it, or you can keep it in case you need to reinstall the program.


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XPUsing a Web Browser to Download an FTP Client Program


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XPUsing an FTP Client to Download WinZip

• File compression programs compress files to decrease the amount of space they require and also to decrease the time it takes to upload and download files.

• WinZip is a popular file compression program which is available for free during its evaluation period.

• When you use an FTP client program to save a site’s address and your user name and password, you are creating an FTP session profile.


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XPUsing an FTP Client to Download WinZip

• Log on to the remote computer by supplying its URL, your user name or anonymous, and your password.

• Navigate to the file you want to download.

• Click the filename on the remote computer to select it.

• If necessary, select binary or ASCII transmission mode.

• Execute the command that downloads the file from the FTP site to your computer and end the FTP session by disconnecting from the remote computer.


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XPCompressing andDecompressing Files

• Internet files of all types are frequently stored in compressed form.

• Compressed files use less space when stored and they take less time to be transferred from one computer to another.

• You can use a file compression program to decrease the original size of most files.

• After you download a compressed file, you must use a program to restore the file to its original state before you can open or execute it.


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• The process of restoring a compressed file to its original state is called file decompression, or file expansion.

• FTP recognizes most compressed files by their extensions.

• The most common extension is .zip, which is why some people refer to compressed files as zip files or a zip archive.

• If you download a compressed file, you must have a file compression program installed on your computer to view its contents.


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XPTracing an Internet Route

• Mirror site: a replica of an existing server that provides an alternate location for downloading files.

• The distance between your PC and a remote computer on the Internet is measured in hops.

• Hop: a connection between two connections.

• You can count the hops and identify the computers between your PC and a remote computer using the Windows tracert (for trace route) program.


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• You can use the tracert program to make an informed choice when selecting a download site.

• Tracert will show you up to 30 hops and indicate the response time, the site name, and the IP address of each hop along the route.

• Ping (Packet Internet Groper): a program that tests a computer to determine if it is connected to the Internet.


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XPUsing Online Storage Services

• When you use an ISP for your Internet connection and e-mail services, you might also receive some free space to use to store a Web site or files.

• Many services have evolved to meet the increased need for ways to store and share files. FTP sites are one way of sharing and storing files.

• ISPs and other entities have started providing three or more megabytes of storage space on their servers, either free or for a fee, creating a new business model.


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• Users access the online storage space using an FTP client program, a program or other interface provided by the provider, or a Web browser.

• The space is secured with an account name and password and permits the sharing of files by many users.

• Many businesses rely on online storage services to send and receive large files while employees are traveling or as a normal course of business.


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• Many individuals use online storage services to store computer backup files, collections of sound files, personal Web sites, and other data.

• As a result of bandwidth problems, many online storage providers have changed their policies to limit the number of transfers and amount of space provided, to charge a small monthly fee for use of the space, or a combination of both.

• Some online storage providers come and go on a regular basis so it is important to backup important files and keep a copy of them locally.


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XPOnline Storage Providers

• Some popular online storage providers are: Xdrive Technologies My Docs Online Yahoo! Briefcase

links for learning about xdrive services and features


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XPCollaborative Authoringon the Web

• Using the Internet to collaborate on files has been discussed since the first Web browser was created in 1994.

• Collaboration: a method for multiple developers or authors to work on the same file without having to download it, edit it, and transfer it back to the original author(s).

• The desire for transferring and editing files over the Internet using the HTTP protocol led to a new protocol for the Internet known as WebDAV.


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• WebDAV (DAV): Web Distributed Authoring and Versioning is a standard extension of the original HTTP 1.1 protocol that is used to transfer Web pages over the Internet.

• Because HTTP has built-in features that provide security and other desirable features during file transfers, it provides collaboration features on the Internet.

• WebDAV Working Group: the group of individuals who are actively collaborating on defining this new protocol.


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• The WebDAV Working Group is dedicated to developing and improving the WebDAV protocol on the Internet to create an operating-system neutral form of collaborative authoring.

• Internet Engineering Task Force (IETF): a large group of individuals who contribute to the evolution of new and existing Internet technologies.

• Four important features that make the WebDAV protocol desirable are file locking, properties, name space management, and collections.


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• WebDAV is available today with some limitations. The Web Publishing Wizard, which is part of the Windows XP operating system, lets you transfer files directly to an Internet server using the HTTP protocol.

• Windows refers to WebDAV as “Web folders.”

• To download a file using Windows XP and the HTTP protocol with WebDAV, you can create a network place, which is a shortcut to a Web site, FTP site, network location, or online storage provider.

• After creating the network place, you can download, upload, and share files at the network location you defined.


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XPSummary

• You can use a Web browser and an FTP client program to transfer files between computers connected to the Internet.

• You can use a download site to evaluate freeware, shareware, limited edition, and full use programs based on your needs.

• You can use online storage providers to store files that you can share with other users.

Downloading and Storing Data

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